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A3000 Service Manual

1. Note The RST signal is the system reset signal driven by IOC on power up or by the keyboard reset switch It is an open collector signal and expansion cards may drive it also if this is desirable The pulse width should be at least 50ms 30 A3000 expansion 43000 Service Manual Disassembly and reassembly DANGER DANGEROUS VOLTAGES ARE EXPOSED INSIDE THE CASE OF THE COMPUTER WHEN THE COVER IS REMOVED THE COMPUTER SHOULD BE DISCONNECTED FROM THE MAINS SUPPLY BEFORE THE COVER IS REMOVED Removing the cover To remove the cover from the computer follow this procedure 1 Disconnect all peripherals and unplug the computer from the mains supply 2 Unplug the mouse connector from the underside of the computer 3 Remove the centre fixing screw on the underside of the case 5 Unhook the two clips and slightly lift up the back of the cover pivoting on the front 6 Locate the three rectangular holes on the front underside of the case Insert a screwdriver into the rear edge of each of these holes in turn Push and twist until the catch comes free of the lower case 7 Repeat this procedure for the other two holes until the cover lifts clear Fitting is the reverse of the above procedure ignoring step six Removing the keyboard WARNING The keyboard connector can be damaged by incorrect handling Hold it by the white plastic strengthening strip only Do not touch the track faces or apply
2. 1772 6854 6551 HD63463 HD63463 HD63463 HD63463 HC374 HC574 HC574 Podule Podule Podule Podule Podule Podule Podule Podule Podule Use Floppy disc controller Econet controller Serial line controller Hard disc Hard disc Hard disc Hard disc Printer Data Latch B Latch A Reserved Internal expansion Internal expansion Internal expansion Internal expansion External expansion External expansion External expansion External expansion Extended ext expansion If fitted not fitted System description 3000 I O programming details External latch A External Latch A is a write only latch used to control parts of the floppy disc sub system 7 6 5 4 3 2 1 0 pee noc ss uss use ust so Floppy disc sel Floppy motor System description Floppy disc 0 Floppy disc 1 Floppy disc 2 Floppy disc 3 Side select Motor on off In Use control These bits select the floppy disc drive 0 through 3 when written LOW Only one bit should be LOW at any one time This controis the side select line of the floppy disc interface 0 Side 1 upper 1 Side 0 lower This bit control the floppy disc orvotf control motor line Its exact use depends on the type of drive This bit controls the IN USE line of the floppy disc Its exact use depends on the type of drive Not used External latch B Service Manual The External Latch B is a write only register
3. System clock failure If the computer is powered on for more than a few seconds and there is no system clock there is a risk that all four ARM chips may be damaged as well as the RAM Faulty MEMC if MEMC is faulty or the RAS CAS signals are not being generated the RAM may be damaged if the machine is left on too long If you suspect a fault in these areas scope the RAS and CAS lines for a few seconds in order to make sure that they are still active then turn the machine off Do not leave the computer on for more than a few seconds at a time Antistatic precautions It is a recommended requirement that anti static precautions should be utilised at all levels of servicing ie antistatic matting and wrist straps 33 34 Service Manual Checking a dead computer Notes 1 For the VIDEO CHECKS see the section entitled Video faults in the Chapter Main PCB fault diagnosis amp repair 2 For the SOUND CHECKS see the algorithm overleaf 3 If the WHITE DISPLAY is not OK check that ail the links have been correctly set before checking SKT 14 Fault diagnosis A3000 Checking the sound system for faults Note Both SoundDMA and SoundChannel modules must be active ie not unplugged before starting this test TYPE AUDIO ON TYPE SPEAKER ON EM m o m KK PRESS CTRL G BELL SOUND YES REPLACE LEAD SPEAKER amp RETEST OK NOW PERFORM AUDIO TESTS IN LAST CHAPTER
4. 0800 476 CONR 20W WAFR 0 1 ST 10mm 3 1040 0750 086 IC 74AC86 CMOS 14 0 3 1 1C41 2201 367 IC VIDC 1A PLSTC 1 IC42 0749 573 IC 74HCT573 CMOS 20 0 3 1 swt 0805 704 SW 2P MOM CO P B RA PCB 1 IC43 0747 573 IC 74HC573 CMOS 20 0 3 1 IC44 2201 375 IC MEMC 1 A PLSTC 8MHz 1 IC45 0749 573 IC 74HCT573 CMOS 20 0 3 1 x1 0820 019 XTAL 1 8432MHz HC18 1 1C46 0747 573 IC 74HC573 CMOS 20 0 3 1 X2 0821 327 XTAL 32 768KHz CC 0 05 1 IC47 0747 004 IC 74HC04 CMOS 14 0 3 1 X3 0820240 XTAL 24 00MHz HC18 1 Main PCB fault diagnosis amp repair 53 3000 2Mb RAM upgrade 0280 200 0180 200 A 0180 200 C 0680 102 0635 470 0635 470 0704 118 0800 488 0800 488 0800 488 per batch 54 Description BARE PCB ASSEMBLY DRAWING CIRCUIT DIAGRAM CPCTR DCPLR 100n AXA 25V CPCTR 47u ALEC 16V RAD CPCTR 47u ALEC 16V RAD IC DRAM 256Kx4 120n 20ZIP CONR 20W SKT 0 r RA PCB CONR 20W SKT 0 1 RA PCB CONR 20W SKT 0 1 RA PCB Service Manual User Port MIDI upgrade 0180 300 A 0180 300 C 0280 360 0800 128 0884 042 0500 000 0502 222 0502222 0502 221 0502 221 0502 221 0502 221 0502 102 0502 222 0502 222 0502 221 0502 103 0502 103 0635 230 0680 002 0706 525 0799 504 0280 320 0740 006 0732 691 0747 139 0794 148 0800 009 0800 004 0800 004 0800 004 0800 475 0800 475 per batch ASSEMBLY DRAWING CIRCUIT DIAGRAM PCB REAR PANEL SKT IC 28 0 6 NORM RIVET POP D
5. Podule FIQ request Force FIQ request This bit indicates that a Floppy Disc Data Request has occurred This bit indicates that a Floppy Disc Interrupt Request has occurred Floppy disc interrupt request This bit indicates that an Econet Interrupt Request has occurred See IOC data sheet for details This bit indicates that a Podule FIQ Request has occurred Econet Interrupt request C 3 5 Podule FIQ req This bit allows an FIQ interrupt request to be generated Force 11 A 3000 Control port The control register allows the external control pins C O 5 to be read and written and the status of the PACK and VFLY inputs to be inspected The C 0 5 bits manipulate the C 0 5 1 0 port When read they reflect the current state of these pins When written LOW the output pin is driven LOW These outputs are open drain and if programmed HIGH the pin is undriven and may be treated as an input On reset all bits in the control register are set to 1 7 6 5 4 3 2 1 o ety pacejswurk ron sc soa 12C serial bus data 12C serial bus clock Floppy disc ready Reserved Aux IO connector Sound mute PACK 8 Test Mode Video vert flyback must be written 1 Allows the state of the VFLYBK signal to be inspected This bit will be read HIGH during vertical flyback and LOW during display See VIDC datasheet for details This bit M
6. TEST PROGRAM 10 20 30 40 50 60 70 80 90 REM gt Check all channels VOICES 8 FOR channel 1 TO B OSCLI Channelvoice STRS channel STR 2 NEXT FOR channel 1 to 8 SOUND channel 15 100 24 PRINTchannel k GET 100 NEXT RUN PROGRAM PRESS A KEY AND REPEAT EIGHT TIMES PRINTS CHANNEL NUMBER TO THE SCREEN AND PLAYS VOICE 2 FOR EACH CHANNEL Fault diagnosis Service Manual 35 3000 Functional tests Notes e Please read the following section General test procedure before you carry out any of the tests For details of how to repair the main PCB see Main functional test Introduction The A3000 test disc enables the engineer to test the functionality of the computer and Acorn upgrades and to isolate any faults which may appear The functional test cannot of course be run on a dead computer see the previous section for advice on diagnosing faults in dead computers General test procedure The A3000 computer mouse expansion cards Test disc Port Tester assembly and Econet cables are designed and specified by Acorn Computers Ltd and may not be changed without written consent from Acorn All items should be complete with the correct cables so that you can connect them to the A3000 computer Equipment required A3000 computer to be tested Mouse e 3 5 inch Test disc part number 0280 032 Two ADFS 800k D formatted write enabled 3 5 inch discs to be
7. 3000 Service Manual A 3000 Service Manual Copyright Acorn Computers Limited 1989 Neither the whole nor any part of the information contained in nor the product described in this Guide may be adapted or reproduced in any material form except with the prior written approval of Acorn Computers Limited The products described in this manual are subject to continuous development and improvement All information of a technical nature and particulars of the products and their use including the information and particulars in this Manual are given by Acorn Computers Limited in good faith However Acorn Computers Limited cannot accept any liability for any loss or damage arising from the use of any information or particulars in this manual or any incorrect use of the products All maintenance and service on the products must be carried out by Acorn Computers authorised dealers or Approved Service Centres Acorn Computers Limited can accept no liability whatsoever for any loss or damage caused by service maintenance or repair by unauthorised personnel All correspondence should be addressed to Customer Service Acorn Computers Limited Fulbourn Road Cherry Hinton Cambridge CB1 4JN Information can also be obtained from the Acorn Support Information Database SID This is an on line viewdata system available to registered SID users Initially access SID on Cambridge 0223 243642 this will allow you to inspect the system and use a respons
8. Repairing faults When repairing an A3000 computer you should repair the faults in the order in which they occurred during the test ie repair the first recorded failure FIRST For further information on checking for faults and carrying out repairs refer to the appropriate section of this manual Restoring the CMOS RAM After passing the soak test the unit under test needs to be restored to the customer s configuration This is carried out by reloading the CMOS RAM from the data disc saved earlier by selecting the Load Save CMOS RAM option from the main menu Then select the Load option after inserting the Data disc when Fault diagnosis Service Manual prompted See Saving and restoring the CMOS RAM above for details of the test procedure Packing After servicing repack the A3000 computer in its box To avoid damage do NOT send the computer through the post or by courier unless it is in its original packaging The original packaging should be checked for damage to the outer casing and poly inserts 37 43000 Main computer tests Running the test Run the main functional test software as follows Ensure that CMOS RAM contents have been saved to disc by using the Load save cmos ram option described above Then restart the system with a delete power on To perform a delete power on do the following Whilst holding down the lt Delete gt key turn the computer on Note that the lt Delete gt key nee
9. The sample bytes are read out at a constant sample rate programmed into the 8 bit Audio Frequency Register This may be programmed to allow samples to be output synchronously at any integer value between 3 and 255 microsecond intervals The sample data bytes are treated as sine plus seven bit logarithmic magnitude and after exponential digital to analogue conversion de glitching and sign bit steering are output as a current at one of the audio output pins to be integrated and filtered externally VIDC also contains a bank of eight stereo image position registers each of three bits These eight registers are sequenced through at the sample rate with the first register synchronised to the first byte clocked out of the FIFO Every sample time is divided into eight time slots and the three bit image value programmed for each register is used to pulse width modulate the output amplitude between the LEFT and RIGHT audio current outputs in multiples of time slot subdivisions This allows the signal to be spatially positioned in one of seven stereo image positions MEMC sound system hardware MEMC provides three internal DMA address registers to support Sound buffer output these control the DMA operations performed following Sound DMA requests from VIDC The registers allow the physical addresses for the START PNTR incremental and END buffer pointers to a block of data in the lowest half Megabyte of physical RAM to be accessed These opera
10. e System clock failure f the computer is powered on for more than a few seconds and there is no system clock there is a risk that all four ARM chips may be damaged as well as the RAM e Faulty MEMC f MEMC is faulty or the RAS CAS signals are not being generated the RAM may be damaged if the machine is left on too long If you suspect a fault in these areas scope the RAS and CAS lines for a few seconds in order to make sure that they still active then turn the machine off Do not leave the computer on for more than a few seconds at a time e Antistatic precautions It is a recommended requirement that anti static precautions should be utilised at all levels of servicing ie antistatic matting and wrist straps 45 A3000 System failure If the system appears to be dead proceed as follows WARNING System clock failure f the computer is powered on for more than a few seconds and there is no system dock there is a risk that all four ARM chips may be damaged as well as the RAM due to lack of refresh on the DRAM 1 Check RAS and CAS on R133 R129 132 2 Check IC41 pin 19 and IC37 pins 1 and 2 for clock signals 3 Check for a RAS signal on pin 5 of all the DRAMS 1 Check for system RESET look for a delayed signal on power on on IC13 pin 29 2 Check that the signal RST driving IC 44 pin 44 and IC 37 pin 9 is not stuck high 3 Check for main system clock of 24 MHz on LK28 f absent check again on
11. 1 R565 0521 473 RES 47K SMD 5 0W25 1206 1 R92 0521 332 RES 3K3 SMD 5 0W25 1206 1 R566 R93 0507 223 RES 22K MF 1 0W25 1 R567 N F R94 0521 560 RES 56R SMD 5 0W25 1206 1 R571 0521 473 RES 47K SMD 5 0W25 1206 5 R95 0507 223 RES 22K MF 1 OW25 1 R572 0521 221 RES 220R SMD 5 0W25 1206 1 R96 0506 250 RES 332R MF 1 0W25 E96 1 R573 R97 0507 223 RES 22K MF 1 0W25 1 R579 N F R96 0507 223 RES 22K MF 1 0W25 1 R99 0507 223 RES 22K MF 1 0W25 1 R100 0521 330 RES 33R SMD 5 0W25 1206 1 Cl 0681 001 PCPCTR DCPLR 33n SMD 1210 1 R101 0521 332 RES 3K3 SMD 5 0W25 1206 1 C2 0631 033 CPCTR CPLT 33p 30V 2 1 R102 0506 161 RES 43R2 MF 1 0W25 E96 1 C3 0640 473 CPCTR CER 47n 30V 80 1 R103 0506 161 RES 43R2 MF 1 0W25 E96 1 C4 0610 010 CPCTR TANT 10u 10V 20 1 R104 0506 161 RES 43R2 MF 1 0W25 E96 1 C5 0681 001 CPCTR DCPLR 33n SMD 1210 1 R105 0521 681 RES 680R SW 5 0W25 1206 1 C6 R106 0521 103 RES 10K SMD 5 0W25 1206 1 C10 0635 100 CPCTR ALEC 10u 16V RAD 5 R107 0521 103 RES 10K SMD 5 0W25 1206 1 C11 0681 001 CPCTR DCPLR 33n SMD 1210 1 R108 0521 331 RES 330R SMD 5 0W25 1206 1 C12 0635230 CPCTR ALEC 220u 16V RAD 1 R109 0521 103 RES 10K SMD 5 0W25 1206 1 C13 0610 010 CPCTR TANT 10u 10V 20 1 R110 C14 0635 230 CPCTR ALEC 220u 16V RAD 1 R115 0506 300 RES 1K00 MF 1 0W25 E96 4 C15 0635 470 CPCTR ALEC 47u 16V RAD 1 R114 0521 122 RES 1K2 SMD 5 0W25 1206 1 C16 0631 012 CPCTR CPLT 12p 30V
12. 2 1 R115 C17 0681 001 CPCTR DCPLR 33n SMD 1210 1 R128 0521 680 RES 68R SMD 5 0W25 1206 14 C18 0681 001 CPCTR DCPLR 33n SMD 1210 1 R129 C19 0635 100 CPCTR ALEC 10u 16V RAD 1 R133 0521 220 RES 22R SMD 5 0W25 1206 5 C20 0681 001 CPCTR DCPLR 33n SMD 1210 1 R134 0521 122 RES 1K2 SMD 5 0W25 1206 1 C21 0681 001 CPCTR DCPLR 33n SMD 1210 1 R135 0521 330 RES 33R SMD 5 0W25 1206 1 C22 0610 010 CPCTR TANT 10u 10V 20 1 R136 0521 221 RES 220R SMD 5 0W25 1206 1 C23 0631 100 CPCTR CPLT 100p 30V 2 1 R137 0521 103 RES 10K SMD 5 0W25 1206 1 C24 R138 0521 680 RES 68R SMD 5 0W25 1206 1 C31 0630 220 CPCTR CPLT 2n2 30V 10 8 R139 0521 680 RES 68R SMD 5 0W25 1206 1 C32 0631 100 CPCTR CPLT 100p 30V 2 1 R140 0521 680 RES 68R SMD 5 0W25 1206 1 C33 0631 100 CPCTR CPLT 100p 30V 2 1 R141 0521 220 RES 22R SMD 5 0W25 1206 1 C34 0610 010 CPCTR TANT 10u 10V 20 1 R142 0521 220 RES 22R SMD 5 0W25 1206 1 C35 0681 001 CPCTR DCPLR 33n SMD 1210 1 R143 0521 220 RES 22R SMD 5 0W25 1206 1 C36 0681 001 CPCTR DCPLR 33n SMD 1210 1 R144 0521 103 RES 10K SMD 5 0W25 1206 1 C37 0681 001 CPCTR DCPLR 33n SMD 1210 1 R145 0521 472 RES 4K7 SMD 5 0W25 1206 1 C38 N F R500 0521 333 RES 33K SWD 5 0W25 1206 1 C39 0621 470 CPCTR ALEC 47u 10V AX 1 R501 0521 103 RES 10K SMD 5 0W25 1206 1 C40 R502 0521 472 RES 4K7 SMD 5 0W25 1206 1 C47 0681 001 CPCTR DCPLR 33n SMD 1210 8 R503 C48 0681 003
13. System description 3000 Keyswitch mapping Service Manual Key Key Size Name Row code Col code Notes Esc F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 Print Scroll Break 2233333333333 OOO OOOO O ee eee ee TAMOOUWUPrPODTDAaARONSO NN D D ND D ND ND ND ND NN NOO REGON 1 Backspc Insert Home Pgup Numlock 2332333333333 2 DD DDD aa m 1 mi 1 mi mi mi i mi mi 2 OBGWNP C I MUOUWUPO NOO0OBONP 21232222 System description Key Key Row Col Notes Size Name code code 1 5 Tab 2 6 1 1 Q 2 7 1 W 2 8 1 E 2 9 1 R 2 A 1 T 2 B 1 Y 2 C 1 U 2 D 1 I 2 E 1 O 2 F 1 P 3 0 1 E 3 1 1 3 2 1 5 3 3 1 Delete 3 4 1 1 Copy 3 5 1 1 Pgdwn 3 6 1 1 7 3 7 1 8 3 8 1 9 3 9 1 3 A 1 1 75 Ctrl 3 B 1 3 1 A 3 C 1 S 3 D 1 D 3 E 1 F 3 F 1 G 4 0 1 H 4 1 1 J 4 2 1 K 4 3 1 L 4 4 1 R 4 5 1 a 4 6 2 25 return 4 7 1 1 4 4 8 1 5 4 9 1 6 4 A 1 4 B 1 Row and column codes are in Hexadecimal Notes 1 Key colour dark grey 2 Key colour red 3 Key position with N key roll over 4 Green light emitting diode under key cap 17 A 3000 Service Manual Key Key Row Col Notes Size Name code code VAZZW lt OXN O1 O1 O1 O1 O1 O1 O1 O1 O1 O1 O1 SS ESE O D gt oO O1 B amp N 1 MO Caps Alt Space Alt Ctrl crsrLt crsrDn crsrRt 0 D0000000000
14. data cable Econet Upgrade Module Socket Pin Signal Pin Signal 17 way header used in conjunction with 2 Dcirq 20 Step SKS to provide the electrical connection 4 In use 22Writedata point for the internal Econet upgrade 6 Sel 3 24 Writegate module This module is identical to that A BE gt WM used in the BBC Master series and e ritepro im A 12 Sel 1 30 Readdata Archimedes computers 1 AH A R RY Ram Upgrade Connector 18 Hoari E A 60 way SIL pin row providing all the necessary signals for the Acom 1MByte 1 3 13 15 17 19 21 23 25 27 29 31 33 all OV Ram upgrade card 5 7 9 11 OV via LK21 A Sia qe Internal Expansion T Faston tab for connection of Earth from the These connectors jointly form the intemal power supply expansion facility and are in the form of PL3 Y two17 way hea for SK3 amp 11 and two a eS Faston tab for connection of OV from the 5 way headers for SK8 4 9 power supply PLA v s SK3 amp SK11 form an 8 bit simple xa Faston tab for connection of 5V from the bus SK3 11 8 amp 9 form an 8 bit M MC power supply podule bus PL2 Yes Serial Port IBM PC AT Pinout full specification of this expansion 9 Way D type plug interface is provided in the chapter PNE headed A3000 Expansion Although the plug is fitted the interface electronics are an upgrade consisting of Keyboard Interface IC7 LT1133 Two 20 way flexible PCB connectors IC1 65C51 providing an interface to the keyboard Pin Signal P
15. defined as transparent making possible cursors of many shapes It can be positioned anywhere on the screen The sound system implemented on the device can support up to 8 channels each with a separate stereo position DATA BUS BUFFER CONTROL VO CONTROLLER INTERFACE LA 14 LA 15 Service Manual The I O system The I O system is controlled by the I O Controller IOC and the Memory Controller MEMO The I O Bus supports all the internal peripherals and the expansion cards Details of the expansion bus can be found in the chapter entitled A3000 expansion This section is intended to give the reader a general understanding of the A3000 l O system and should not be used to program the l O system directly The implementation details are liable to change at any time and only the published software interfaces should be used to manipulate the I O system Future systems may have a different implementation of the I O system and in particular the addresses and number of expansion card locations may move For this reason and to ensure that any device may be plugged into any slot all driver code for expansion cards must be relocatable References to the direct expansion card addresses should never be used ltis up to the machine operating system in conjunction with the expansion card ID to determine the address at which an expansion card should be accessed To this extent some of the following sections are for background
16. for 2764 27128 The User port is the same Port B The VIA interrupts go through a link which is not normally fitted The MIDI section is not the same The ADC and 1 MHz bus are not fitted to the UPM MIDI EXPANSION CARD e The UART is the same Signetics 2691 but is at a different address see below The ROM page latch is not the same E LA13 LAI2 offset address amp 2000 2FFC amp 3000 3FFC MiDi Podule 1 0 82000 UPM upgrade 1 1 83000 26 Component ROM EPROM 271 28 as standard 16k x 8 bit Larger EPROMS can be fitted if the links marked X are cut between pins 1 amp 2 and relinked 2 to 3 Eprom size 2764 27128 27256 27512 1M bit JEDEC 2m bit 4m bit Contains the iD byte 63 dec The start up information must be at the top ofthe ROM VIA 65C22 2Mhz part Port A PA lt 7 0 gt used to page the ROM CAs Not Used Port B PB lt 7 0 gt CB1 and CB2 for the User Port Use 2Mhz synchronous cycle to access the VIA The interrupt output connects directly to PIRQ No User Port interrupt handler provided UART 2691 For the MiDi interface A3000 expansion A 3000 Service Manual Fitting an Internal expansion card 1Mb RAM upgrade This procedure covers the fitting of an internal expansion card such as the User Port MIDI expansion card This work should only be carried by The A3000 computer RAM can be upgraded from 1Mb Acorn Dealers or Approved Service C
17. ie Mode Shunt 2 3 ie CSync Shunt NF ie VSync Shunt NF ie HSync None None Trk 1 2 Shunt on Iss1 Trk 1 2 Shunt on Iss 1 None None Link Fitted Effect Default LK8 No LKQ No LK10 No Used to set nationality id of LK12 Trk LK11 No the keyboard le UK LK12 No LK13 No LK1 No Used to optionally link OV to NF LK2 No the RFI Shield Earth INF LK3 No NF Connection point for a design backup self contained keyboard P1 Krst Keyboard reset P2 NC P3 0V P4 5V P5 Krx From keyboard PS Ku To keyboard LK4 N NF 9 Connection point for design backup mouse to keyboard link P1Xr Xref P5Sw 1 Switch 1 P2 Xd X dir P6 Sw 2 Switch 2 P3 Yr Yref P7Sw 3 Switch 3 P4 Yd Ydir P8 OV LK17 Not Used in conjunction with LK18 EA rk 1 to select ROM device type Shunt jon Iss1 Used in conjunction with LK17 Trk 1 2 LK18 Not a to select ROM device type je Non JEDEC ROM LK17 LK18 Shunt 512K EPROM 1 2 1 2 pn lss1 Non JEDEC 1M ROM 1 2 1 2 Non JEDEC 1M EPROM 1 2 1 2 JEDEC 1 214M ROM EPROM 1 1 2 2 LK16 No Used to select the design Trk 2 3 backup keyboard See LK3 le Main K B 1 2 Selects backup keyboard 2 3 Selects main keyboard LK21 No Trk 2 3 Selects the 5V power feed to le not via the floppy disc drive to be via data cable the data cable or by separate feed with PLS 1 2 5V via data cable 2 3 5V via separate cable LK14 No Used in conj
18. labelled Scratch Disc and Data disc e Serial port loopback plug for A3000 Acorn part number 0280 087 See the Appendix for details Epson FX80 or Olivetti JP101 printer e Pair of 32 ohm stereo headphones Mono monitor Analogue RGB monitor Note You can replace the specified printers with any other manufacturer s direct functional equivalent in terms of BOTH hardware interface and software Removing the top cover of the computer main unit Remove the top cover of the A3000 computer as detailed in the previous chapter Disassembly and Assembly Connecting up the equipment Connect the e serial port loopback plug to the SERIAL socket e printer to the PARALLEL PRINTER port 36 Service Manual headphones to the Headphones 32 ohm socket monochrome monitor to the MONO VIDEO socket analogue RGB monitor to the ANALOGUE RGB socket monitors to the mains supply A3000 computer to the mains supply Connecting and disconnecting the power e You must CONNECT the power only when you have made all the other connections You must DISCONNECT the power before removing any other connections Validating the test equipment Before carrying out any of the tests in this section validate the test equipment using a known good system If the test equipment fails you should repair the test equipment and retest on a known good part Before you start Before the start of each day or testing
19. occur The X and Y counters are cleared upon each transfer to the transmit holding registers Therefore the count values are relative to the last values sent The ARM acknowledges the first byte Xcount with a BACK code and the second byte Ycount with any of NACK MACK SACK SMAK A protocol failure causes the keyboard controller to enter the error process ON error When transmission of non zero mouse data is enabled the keyboard controller gives key data transmission priority over mouse data except when the mouse counter over underflows Acknowledge codes There are seven acknowledge codes which may be sent by the ARM RAK1 and RAK2 are used during the reset sequence BACK is the acknowledge to the first byte of a two byte keyboard data set The four remaining types NACK MACK SACK and SMAK acknowledge the final byte of a data set NACK disables key scanning and therefore key up down data transmission as well as setting the mouse mode to send data only on ROMP request SACK enables key scanning and key data transmission but disables unsolicited mouse data MACK disables key scanning and keydata transmission and enables the transmission of mouse count values it either X or Y counts are non zero SMAK enables key scanning and both key and mouse data transmission It combines Mnemonic msb Isb Comments HRST 1111 1111 One byte command keyboard reset RAK1 1111 1110 One byte response in reset protocol RAK2 1111 1101 O
20. of these resistors may be removed in order to isolate the DRAM bank from the CPU thus easing the tracing of shorts etc Also check for short or open circuits on the BDATA bus IC 43 pins 12 to 19 and IC 46 pins 12 to 19 46 Service Manual 9 Check for shorts on the DRAM address bus either on the DRAMS themselves or on IC 44 pins 28 to 37 Check all data signals on IC41 10Check for Data and Address signals on all four of the ROMs This is especially important if a ROM change has been carried out as misuse of a screwdriver during ROM removal may have damaged or broken PCB tracks socket or ROM legs an IC extraction tool should have been used 11 Check the processor interrupt lines FIO and IRO pins 8 and 7 on ARM IC 37 Neither of these should be stuck low IRO can be expected to pulse low FIO should be high These interrupts should also be checked at their source on IOC 1C13 pins 50 and 51 Should these also be low the interrupt source can be traced by examining all interrupt inputs to IOC IC 13 on pins 30 to 42 note that pins 30 31 and 42 are active high logic Main PCB fault diagnosis amp repair 3000 Test ROMs The A3000 Test ROMs are designed to assist in the repair of all A3000 systems where Failure to Initialise faults are present ie the machine appears to be dead on power up The ROMs contain software which can be categorised in two sections 1 Main memory test routines 2 Test routines f
21. or perform the Video tests in the next chapter and repair as necessary Keyboard Functional test LEDs This test checks that the LEDs Caps Lock Scroll Lock and Num Lock are working Keys stuck During this test any keys or mouse buttons which are in a permanently closed position ie stuck down are displayed on the screen If any keys are permanently closed then it will be impossible to continue the test If everything is normal and no keys are stuck then the last key pressed clears the screen and the Test program passes straight on to the next test 40 Service Manual To carry out this test 1 Follow the instructions which appear on the screen These tell you when to check that each LED is ON and OFF 2 Note down any LED failures before continuing the test These are not recorded 3 After each set of instructions press Break to move to the next instruction Mouse This tests the three buttons on the mouse and the movement of the mouse to the left right up and down Each of the mouse buttons ie left middle right are displayed on the screen in turn together with a pointer You should 1 Move the mouse until the pointer is within the box on the screen then press the button displayed on the screen 2 The box displayed on the screen should disappear and the next button appear If the button cannot be made to disappear then it will be IMPOSSIBLE to continue the test You should repeat the test with t
22. pressure to the cable itself 4 Remove the two screws from the clips at the rear of the computer Disassembly and reassembly 1 Follow the procedure for removing the cover 2 Unplug the keyboard connector and lift the keyboard out from the lower case Fitting is the reverse of the above procedure Removing the floppy disc drive 1 Follow the procedure for removing the cover 2 Disconnect the power supply cable from the drive and the ribbon cable from the PCB 3 Remove the keyboard see above 4 Turn the lower case upside down and support the drive on a foam pad 5 Remove the four recessed drive fixing screws 31 A 3000 6 Tturn the case back up again Lift the drive clear Fitting is the reverse of the above procedure Removing the PSU 1 Follow the procedures for removing the cover and the keyboard above 2 Disconnect the two faston connectors from the PCB the connector on the PSU and the power cable to the disc drive 3 Remove the warning sticker on top of the PSU cover If the PSU is held in place by a plastic rivet release the rivet jaws by pushing the pin in the centre of the jaw down and then push the rivet itself down If a self tapping retaining screw is fitted this should be should be unscrewed The PSU and its cover will then lift out Replacing the PSU When replacing the PSU ensure that the plastic insulating film is re
23. responsible for selecting the LED status After the reset sequence key scanning will only be enabled if a scan enable acknowledged SACK or SMAK was received from the ARM Data transmission When enabled for scanning the keyboard controller informs the ARM of any new key down or new key up by sending a two byte code incorporating the key row and column addresses The first byte gives the row and is acknowledged by a byte acknowledge BACK code from the ARM If BACK was not the acknowledge code then the error process ON error is entered If the BACK code was received the keyboard controller sends the column information and waits for an acknowledge If either a NACK SACK MACK or SMAK acknowledge code is received the keyboard controller continues by processing the ACK type and selecting the mouse and scan modes implied If the character received as the second byte acknowledge was not one of NACK MACK SACK SMAK then the error process is entered Mouse data Mouse data is sent by the keyboard controller if requested by a ROMP request from the ARM or if a SMAK or MACK have enabled transmission of nonzero values Two bytes are used for mouse position data Byte one encodes the accumulated movement along the X axis while byte two gives Y axis movement Code values Service Manual Both X and Y counts must be transferred to temporary registers when data transmission is triggered so that accumulation of further mouse movement can
24. selection of IC13 IOC SVPMD low SVPMD low IC44 pin 52 SVPMD low and IC37 pin 10 OC CS 8 S1 OC CS amp S2 OC CS 8 S3 OCCS amp S4 OCCS amp S5 OCCS amp S6 OC CS 8 S7 1C13 pin 67 pin 63 pin 62 pin 61 pin 59 pin 58 pin 57 pin 56 1C44 pin 63 and IC37 pin 84 IOC CS 8 CO IOC CS 8 C1 IOC CS 8 C2 10C CS 8 C3 IOC CS 8 C4h IOC CS 8 C5 IOC CS 1C13 pin 67 pin 44 pin 45 pin 46 pin 47 pin 48 pin 49 LDRT ro r5 SVPMD pin low LDRT ro 1 5 continual toggle of LDRT r0 r5 LDR rl iocmof re load ioc base addr offset LDR 1 0 r1 r6 SVPMD pin high LDR ro rl r6 IOC CS pin high Sl ioc hi LDR ro Mily oJ IOC CS pin high 82 toc ht LDR LOS rl r6 IOC CS pin high 1 53 LOC 401 LDR r0 rl r6 IOC CS pin high 7S4 ioc hi LDR ro Eli TEJ IOC CS pin high 7S5 ioc hi LDR ro rly FGri IOC CS pin high 756 ioc hi LDR rod rl r6 IOC CS pin high S7 ioc hi LDRB ro r5 nB W pin high LDRB ro r5 nB W pin high LDRB ro F5 nB W pin high MOV r amp FE0000 A STR ele r7 set CO MOV r amp FDO000 A STR rly r7 gt set Cl MOV E amp FBO000 f STR ely r7 set C2 MOV r 6F 70000 AED Cie STR la r7 set C3 MOV r amp EF0000 7 STR aly r7 set C4 MOV r amp DF0000 STR Plg r7 set g5 MOV r amp FF0000 STR rl r7 i reset all 48 Main PCB fault diagnosis amp repair 43000 Video fa
25. session you must first Adjust the colour monitor to ensure adequate contrast and brightness Inspect all the mechanical parts of the test equipment and replace any parts as necessary Also if required Ensure that the printer has sufficient paper Connect the printer to the mains supply Do NOT turn on Saving and restoring the CMOS RAM The tests alter the contents of the battery backed RAM that holds the A3000 s configuration data These must be saved before any of the tests is run and restored when the last test is over 1 Insert the Test disc into the floppy disc drive 2 Switch on the monitors and computer 3 Type F12 to get to the command line prompt 4 At the RISC OS supervisor prompt an asterisk type the following DRIVE 0 CMOSLS 5 When prompted replace the Test disc with an ADFS 800k write enabled disc the Data disc 6 Type S to save the contents of the RAM or L to load a previously saved copy of the RAM 7 Type the filename to use 8 When prompted replace the Test disc in the drive and press the space bar to continue 9 Put the data disc in a safe place Do NOT use this disc for the later floppy disc test 10Type Q to quit this option Fault diagnosis 43000 Carrying out the tests There are two types of tests subjective and non subjective The test program passes or fails the equipment on the non subjective tests however you must judge whether the equipment passes or
26. shared between several users who must maintain a consistent RAM copy Updates must be made with IRQ disabled 4 2 7 6 1 o s Jw Ps oe c z os em CD 0 2 Printer Strobe Bit 5 6 AUX 1 2 Bit 7 HS3 Reserved 0 Data Separator ol Printer strobe Not used Not used Not used CD 0 2 should be programmed CD 0 2 LOW tor future compatibility CD 1 controls the floppy disc data separator format CD 1 0 Double Density CD 1 1Single Density This controls the floppy disc controller reset line When programmed LOW the controller is RESET This used to indicate valid data on the printer outputs It should be set HIGH when valid data has been written to the printer port and LOW after about Sls Not used Not used A 3000 Interrupts The I O system generates two independent interrupt requests IRQ and FIQ Interrupt requests can be caused by events internal to IOC or by external events on the interrupt or control port input pins The interrupts are controlled by four types of register status mask request and clear The status registers reflect the current state of the various interrupt sources The mask registers determine which sources may generate an interrupt The request registers are the logical AND of the status and mask registers and indicate which sources are generating interrupt requests to the processor The clear register allows clearing of interrupt requests wher
27. sonaron onmo Row and column codes are in Hexadecimal Notes 1 Key colour dark grey Key colour red Key position with N key roll over Green light emitting diode under key cap A ON 18 System description A 3000 Floppy disc drive The floppy disc drive used on the A3000 computer is a one inch high drive taking 3 5 inch floppy discs Performance Capacity Track to track step rate Seek settle time Write to read timing Power on to drive ready Power supply Noise bandwidth Maximum power 3ms 15ms 1200us 1000ms 0 30 MHz 5Vdc 1 5 1 MB unformatted 2 Watts continuous Power connector The power connector is a 4 pin 25mm pitch type The LED is ON when Drive Select and In Use are low or when Drive Select is low Pin Signal 1 5V 2 Ground 3 Ground 4 No connection Interface connector The interface connector is a 34 way 2 row 0 1 inch pitch type with pinouts as shown below i Signal Dir Retn Signal pcb 1 2 Disc change I 3 4 In use I 5 6 Drive select 3 O 7 8 Index I 9 10 Drive select 0 O 11 12 Drive select 1 O 13 14 Drive select 2 O 15 16 Motor ON O 17 18 Direction O 19 20 Step Dsc chg rst O 21 22 Write data O 23 24 Write gate O 25 26 Track 0 I 27 28 Write protect I 29 30 Read data I 31 32 Side 1 select O 33 34 Ready I Optionally 5V System description Service Manual Power s
28. 0 203 FSTN TAB 6 3mmx0 8 ST PCB 1 IC15 0283 023 RISC OS ROM 2 V2 0 1 PLS N F IC16 0283 024 RISC OS ROM 3 V2 0 1 PL6 0803 102 CONR 34W BOX IDC LP ST 1 IC17 0283 025 RISC OS ROM 4 V2 0 1 IC18 0747 574 IC 74HC574 CMOS 20 0 3 1 IC19 0747 574 IC 74HC574 CMOS 20 0 3 1 SKI 0800 920 CONR 9W MINDIN RA PCB 1 IC20 SK2 0800 004 CONR SW SKT DIN RA PCB 1 IC27 0704 118 IC DRAM 256Kx4 120n 20ZIP 8 SK3 0800 487 CONR 17W SKT 0 1 PCB 1 IC28 0747 139 IC 741HC139 CMOS 16 0 3 1 SK4 0800 487 CONR 17W SKI 0 1 PCB 1 Ic29 0747 573 IC 74HC573 CMOS 20 0 3 1 SK5 0800 481 CONR5W SKT HSNG 0 1 PCB 1 IC30 0747 573 IC 74HC573 CMOS 20 0 3 1 SK6 0801 202 CONR 20W 0 1 FLXPCB SKT 1 1C31 0747 573 IC 74HC573 CMOS 20 0 3 1 SK7 0801 202 CONR 20W 0 1 FLXPCB SKT 1 1C32 0770 386 IC LM386 AUDIO AMP 1 SK8 0800 486 CONR 5W SKT 0 1 PCB 1 IC33 0747 139 IC 74HC139 CMOS 16 0 3 1 SK9 0800 486 CONR SW SKT 0 1 PCB 1 IC34 0747 000 IC 74HC00 CMOS 14 0 3 1 SK10 0800 293 CONRD 25W SKT RAPCB RFI I 1 1C35 0740 006 IC 7406 TTL 14 0 3 1 SK11 0800 487 CONR 17W SKT 0 1 PCB 1 0740 016 IC 7416 TTL 14 0 3 OPTION SK12 0800 642 CONR JKSKT 3W 3 5mm RAPCE 1 IC36 0701 772 IC 1772 FDC 28 0 6 1 SK13 0800 611 CONR PHONO SKT RA PCB 1 IC37 2201 365 IC ARM Rum PLSTC 1 SK14 0800 292 CONRD 9W SKT RAPCB RFI Lkh 1 IC38 0770 386 IC LM386 AUDIO AMP 1 SKIS 0800 411 CONR 64W SKT RA AC PCB 1 IC39 0770 324 IC LM324 QUAD OP AMP 1 SK16
29. 0521 472 RES 4K7 SMD 5 0W25 1206 1 C70 0642 103 CPCTR ALEC 100u 25V RAD 1 R548 0521 472 RES 4K7 SMD 5 OW25 1206 1 C71 0681 003 CPCTR DCPLR 100n SMD 1210 1 R549 0521 104 RES 100K SMD 5 0W25 1206 1 C72 0681 003 CPCTR DCPLR 100n SMD 1210 1 R550 0521 472 RES 4K7 SMD 5 0W25 1206 1 C73 0681 003 CPCTR DCPLR 100n SMD 1210 1 R551 0521 472 RES 4K7 SMD 5 0W25 1206 1 C74 0640 473 CPCTR CER 47n 30V 80 1 R552 0521 472 RES 4K7 SMD 5 0W25 1206 1 C75 0630 220 CPCTR CPLT 2n2 30V 10 1 R553 0521221 RES 220R SMD 5 0W25 1206 1 C76 0681 001 CPCTR DCPLR 33n SMD 1210 1 P554 0521 103 RES 10K SMD 5 0W25 1206 1 C77 0650223 CPCTR MPSTR 22n 50V 10 1 R555 N F C78 0610 010 CPCTR TANT 10u 10V 20 1 R556 N F C79 0630 100 CPCTR CPLT 1n 30V 10 1 P557 0521 473 RES 47K SMD 5 0W25 1206 1 C80 0650 106 CPCTR MPSTR 100n 50V 10 1 R558 N F C81 0630 220 CPCTR CPLT 2n2 30V 10 1 R559 N F C82 0630 220 CPCTR CPLT 2n2 30V 10 1 R560 0521 331 RES 330R SMD 5 0W25 1206 1 C83 0621 470 CPCTR ALEC 47u 10V AX 1 R561 0521 271 RES 270R SW 5 0W25 1206 1 C84 0681 003 CPCTR DCPLR 100n SMD 1210 1 52 Main PCB fault diagnosis amp repair AA 3000 Service Manual Item Part no Description Qty Item Part no Description Qty C85 0630 100 CPCTR CPLT 1n 30V 10 1 01 0780 241 TRANS 8C239 NPN 0 2 P LDS 1 C86 0630 220 CPCTR CPLT 2n2 30V 10 1 02 C87 0681 001 CPCTR DCPLR 33n SW 12
30. 10 1 010 0783 907 TRANS 2N3906 PNP 2 P LDS 9 C88 0650 106 CPCTR MPSTR 100n 50V 10 1 011 0780 241 TRANS BC239 NPN 0 2 P LDS 1 C89 0610 010 CPCTR TANT 10u 10V 20 1 012 0780 241 TRANS BC239 NPN 0 2 P LDS 1 C90 0630 220 CPCTR CPLT 2n2 30V 10 1 C91 0630 220 CPCTR CPLT 2n2 30V 10 1 D1 N F C92 0650 223 CPCTR MPSTR 22n 50V 10 1 02 0794 005 DIODE SI 1N4005 600V 1A 1 C93 0635 100 CPCTR ALEC 10u 16V RAD 1 D3 C94 0610 010 CPCTR TANT 10u 10V 20 1 D16 0794 148 DIODE SI 1N4148 14 C95 0635 470 CPCTR ALEC 47u 16V RAD 1 C96 0640 473 CPCTR CER 47n 30V 80 1 B1 BAT NICAD 1V2 280mAH PCB 1 C97 0635 100 CPCTR ALEC 10u 16V RAD 1 0817 013 C98 0681 001 CPCTR DCPLR 33n SW 1210 1 C99 0681 001 CPCTR DCPLR 33n SW 1210 1 C100 0610 010 CPCTR TANT 10u 10V 20 1 C101 N F L1 0500 000 RES ZERO OHM 0W25 0 6 ptch 14 C102 N F L14 0870 420 WIRE 22SWG TIN OPTION C103 N F L15 N F C104 N F L16 0860 015 CHOKE RF FE BEAD 1 C105 0681 001 CPCTR DCPLR 33n SMD 1210 1 L17 0860 015 CHOKE RF FE BEAD 1 C106 0681 001 CPCTR DCPLR 33n SW 1210 1 L18 0860 012 CHOKE RF 2u2H AX 0 30 1 C107 0640 473 CPCTR CER 47n 30V 80 1 L19 0860 005 COIL RF 33uH AX 0 45 1 C108 0610 010 CPCTR TANT 10u 10V 20 1 L20 0860 015 CHOKE RF FE BEAD 1 C109 0621 470 CPCTR ALEC 47u 10V AX 1 L21 0860 015 CHOKE RF FE BEAD 1 C110 0621 470 CPCTR ALEC 47u 10V AX 1 C111 0610 010 CPCTR TANT lOu 10V 20 1 C112 0635 230 CPCTR ALEC 220u 16V RAD 1 LK 1 C113 0
31. 150K 1 22K 1 1000013 R97 150K 1 22K 1 1000013 R98 150K 1 22K 1 1000013 R99 150K 1 22K 1 1000013 R101 33K 3K3 1000013 R105 470R 680R 1000051 R129 33R 22R 1000051 R130 33R 22R 1000051 R131 33R 22R 1000051 R132 33R 22R 1000051 R133 33R 22R 1000051 R137 100K 10K 1000051 R502 6K8 4K7 1000013 R530 22K 1K 1004150 C75 100p CPLT 2n2 CPLT 10 1000013 C77 2n7 CPLT 22n MPSTR 10 1000013 C80 22n MPSTR 100n MPSTR 10 1000013 C81 330p 2n2 CPLT 1000013 C82 330p 2n2 CPLT 1000013 C86 330p 2n2 CPLT 1000013 C88 22n MPSTR 100n MPSTR 10 1000013 C90 100p CPLT 2n2 CPLT 10 1000013 c91 330p 2n2 CPLT 1000013 c92 2n7 CPLT 22n MPSTR 10 1000013 System description Service Manual The following additional modifications were made during the production of Issue A PCBs Serial interface 10K resistor 5 conventional type was added as a pullup to the rear of the PCB connected between the signal Rii IC7 pin 18 and 5V from serial number 1000001 Video genlocking The tracks on the underside of the PCB between the pins of both LK28 and LK29 were cut 2 pin wafers were fitted to LK28 29 amp 30 and shunts to LK28 and 29 but not LK30 from 1000251 12c bus access Two 5 way headers 0800 486 were fitted to SK8 and SK9 from 1000251 JEDEC 8 non JEDEC EPROMs To permit the use of JEDEC and non JEDEC EPROMs tracks on the PCB between the pins of both LK17 and LK18 were cut 2 pin wafers were fitted to LK17
32. 1C47 pins 3 4 5 and 6 and change 1C47 if required Finally change the crystal X3 4 Check SKT 15 for the following 27C to be CLK 2 28C to be CLK 8 and 29C to be Ref 8 5 Check for clocks on IC44 pin 67 and IC41 pin 19 6 Check for the presence and validity of the processor addresses and PHI 1 clock This can be done by examining the signals on IC 29 pins 12 to 19 IC 30 pins 12 to 19 and IC 31 pins 12 to 15 whilst holding down the RESET button RESET can be activated by pressing the RESET key or by short circuiting SKT3 pin 15 and 16 When RESET is held down the address lines will increment not AO and Al Should none of the signals toggle check for the PHI 1 clock on the appropriate IC at its source on IC 44 pin 66 and on R135 Also check to see that addresses are being presented to the inputs of the above devices Change ICs 29 30 or 31 as appropriate or if no addresses are present change the ARM IC 37 7 Check for all address lines on MEMC 1C44 again with RESET held down Check for the presence of LA2 to LA6 and LA16 to LA21 on 10C IC 13 8 The data bus can be inspected by probing on resistors R49 to R65 R115 to R128 and R87 Note that MEMC1A will not enable the ROMs whilst RESET is activated By their nature it is difficult to interpret the signals seen so just check for the ability of the signals to move between logic states None of these lines should be stuck permanently high low or in a midrail state Any
33. 23 22 21 20 19 18 17 16 15 14 Signal Pin Signal Sib Pd 6 15 nc Pd o 9 Pan 16 ne Ack 17 25 OV 22 Service Manual Functlon Specification Econet Socket 5 way Din socket for connection to Econet local area network Note this interface is an upgrade Data Clock Econet Upgrade Module Socket 5 way header used in conjunction with SK4 to provide electrical connections for the Econet upgrade module This module is identical to that used on BBC Master series and Archimedes computers System description A3000 Changes between Issue A and Issue 1 PCBs This manual covers A3000s produced with both Issue A and Issue 1 PCBs and drawings for both versions are included This section summarises the changes made during the production of Issue A boards and the design changes made for Issue 1 Modifications to Issue A PCBs Component value changes The chart below summarises the component value changes made during the production of Issue A PCBs showing the first serial number changed Unless otherwise stated resistors are 5 SMD Comp Issue A Changed to Serial no R67 68R 22R 1000051 R68 68R 22R 1000051 R69 68R 22R 1000051 R70 68R 22R 1000051 R71 68R 22R 1000051 R81 33K 3K3 1000013 R82 150K 1 22K 1 1000013 R85 33K 3K3 1000013 R86 150K 1 22K 1 1000013 R88 33K 3K3 1000013 R89 33K 3K3 1000013 R91 150K 1 22K 1 1000013 R92 33K 3K3 1000013 R93 150K 1 22K 1 1000013 R95
34. 4K7 C MF 5 0W25 1 R6 N F R7 0502 472 RES 4K7 C MF 5 0W25 1 R8 0502 472 RES 4K7 C MF 5 0W25 1 D1 0790 085 DIODE BAT85 SBL 1 D1 0790 085 DIODE BAT85 SBL 1 per batch Main PCB fault diagnosis amp repair 55 56 Service Manual Main PCB fault diagnosis amp repair A 3000 Service Manual Appendix B Earth continuity testing Equipment required An earth continuity tester capable of sourcing 25A derived from an AC source with a no load voltage not exceeding 12V It is recommended that the calibration and operation of the instrument be checked frequently enough to assure its accuracy Test Procedure DANGER THE FOLLOWING TESTS INVOLVE HIGH CURRENTS BUT LOW VOLTAGES ALL NECESSARY PRECAUTIONS MUST BE TAKEN TO ENSURE OPERATOR SAFETY DURING TESTING DANGER SWITCH OFF THE COMPUTER DISCONNECT IT FROM THE MAINS SUPPLY AND DISCONNECT ANY PERIPHERALS BEFORE CARRYING OUT THIS TEST The test should be performed on a fully assembled computer Using the Earth continuity tester check the continuity between the power supply cord 13A plug earth pin and the following points 1 the rear panel internal expansion card fixing screws 2 both printer parallel port D type fixing bolts The resistance measured between the earth pin and each of the above test points shall not exceed 0 15 a This value includes an allowance for the resistance of the mains cable The duration of each test shall not ex
35. 681 001 CPCTR DCPLR 33n SMD 1210 1 LK16 N F C114 0631 010 CPCTR CPLT 10p 30V 2 1 LK17 0800 050 CONR 2W WAFR 0 1 ST PCB 1 C115 0631 033 CPCTR CPLT 33p 30V 2 1 LK18 0800 050 CONR 2W WAFR 0 1 ST PCB 1 C116 0630 270 CPCTR CPLT 2n7 30V 10 1 11 19 0800 051 CONR 3W WAFR 0 1 ST PCB 1 C500 LK20 0800 051 CONR 3W WAFR 0 1 ST PCB 1 0506 0681 001 CPCTR DCPLR 33n SMD 1210 7 LK21 N F LK22 0800 458 CONR 2W WAFR 0 1 ST LK 2 LK23 0800 458 CONR 2W WAFR 0 1 ST LK 2 1C1 N F LK24 0800 051 CONR 3W WAFR 0 1 ST PCB 1 IC2 0280 022 IC KBD CNTRLR 0708 051 1 LK25 0800 050 CONR 2W WAFR 0 1 ST PCB 1 IC3 0740 038 IC 7438 TTL 14 0 3 1 1K26 0800 050 CONR 2W WAFR 0 1 ST PCB 1 IC4 0742 145 IC 74LS145 TTL 16 0 3 1 LK27 0800 050 CONR 2W WAFR 0 1 ST PCB 1 ICS 0742 145 IC 74LS145 TTL 16 0 3 1 LK28 0800 050 CONR 2W WAFR 0 1 ST PCB 1 IC6 0708 583 IC 8583 RTC RAM 8 0 3 1 LK29 0800 050 CONR 2W WAFR 0 1 ST PCB 1 IC7 N F LK30 0800 050 CONR 2W WAFR 0 1 ST PCB 1 IC8 0749 014 IC 74HCT14 CMOS 14 0 3 1 LK31 0800 050 CONR 2W WAFR 0 1 ST PCB 1 IC9 0747 004 IC 74HC04 CMOS 14 0 3 1 IC10 0747 074 IC 74HC74 CMOS 14 0 3 1 IC11 0742 374 IC 74LS374 TTL 20 0 3 1 PL1 0180 013 EARTH STRAP PCB PSU 1 1012 0747 138 IC 74HC138 CMOS 16 0 3 1 PL2 0800 291 CONRD 9W PLG RAPCB RFI LI 1 1013 2201 368 IC 10C PLSTC 1 PL3 0800 203 FSTN TAB 6 3mmx0 8 ST PCB 1 IC14 0283 022 RISC OS ROM 1 V2 0 1 PL4 080
36. A 3000 I O address memory mapping All I O accesses are memory mapped IOC is connected as detailed in this table IOC ARM LA 21 LA 20 Internal register memory map Peripheral address Service Manual Address Read Write 3200000H Control Control 3200004H Serial Rx Data Serial Tx Data 3200008H 320000CH 3200010H IRQ status 3200014H IRQ request A IRQ clear 3200018H IRQ mask A IRQ mask A 320001CH 3200020H IRQ statusB 3200024H IRQ request B 3200028H IRQ mask B IRQ mask B 320002CH 3200030H FIQ status 3200034H FIQ request 3200038H FIQ mask FIQ mask 320003CH 3200040H TO count Low TO latch Low 3200044H TO count High TO latch High 3200048H TO go command 320004CH TO latch command 3200050H T1 count Low T1 latch Low 3200054H T1 count High T1 latch High 3200058H T1 go command 320005CH T1 latch command 3200060H T2 count Low T2 latch Low 3200064H T2 count High T2 latch High 3200068H T2 go command 320006CH T2 latch command 3200070H T3 count Low T3 latch Low 3200074H T3 count High 13 latch High 3200078H T3 go command 320007CH T3 latch command Cycle Base Type Bk Address amp 33 10000 amp 33A0000 amp 3380000 amp 32D0000 amp 32D0020 amp 32D0008 amp 32D0028 amp 3350010 amp 3350018 amp 3350040 amp 3244000 amp 32C4000 amp 3344000 amp 33C4000 amp 3240000 amp 32C0000 amp 3340000 amp 33C0000 amp 3270000
37. ARE EXPOSED INSIDE THE CASE OF THE COMPUTER WHEN THE COVER IS REMOVED THE COMPUTER SHOULD BE DISCONNECTED FROM THE MAINS SUPPLY BEFORE THE COVER IS REMOVED The following internal upgrades are currently available for the A3000 computer User port MIDI internal expansion card 1 Mb Ram upgrade e Serial port Econet module Internal upgrades must be fitted by an Acorn Dealer or Approved Service Centre Interface The electrical signals available on the internal expansion are a subset of those described in A Series podules available from Acorn Customer Service as an Application Note or on the SID system Doc Ref 0310101 The connection is via two 17 way 0 1 inch pitch connectors and two 5 way 0 1 inch connectors the latter fitted as standard to Issue 1 PCBs and later Expansion cards should use 0 025 in square pin headers Expansion bus connectors Pin no SK3 SK11 SK8 SK9 1 5V OV Cro Ov 2 PWE 5v C 1 REF8M 3 PS1 PRE Bl PFIQ 4 CLK2 PR nW IORQ Ms 1 5 LA 2 LA 4 IOGT 5V 6 LA 3 LA 5 7 BD 0 LA 6 8 BD 1 LA 7 9 BD 2 OV 10 BD 3 LA 8 11 BD 4 LA 9 12 BD 5 LA 10 13 BD 6 LA 11 14 BD 7 LA 12 15 RST LA 13 16 OV PIRQ 17 5V OV Note Pin 1 is at the righthand end when viewed from the front of the computer A3000 expansion Service Manual The interface is configured as Podule 1 Module 1 It is recommended that the load on each si
38. CPCTR DCPLR 100n SMD 1210 1 R518 0521 680 RES 68R SMD 5 0W25 1206 16 c 0681 003 CPCTR DCPLR 100n SMD 1210 1 R519 R529 0521 104 RES 100K SMD 5 0W25 1206 11 054 0681 001 CPCTR DCPLR 33n SMD 1210 5 R530 0521 102 RES 1KO SMD 5 0W25 1206 1 C55 0610 010 CPCTR TANT 10u 10V 20 1 P531 0521 181 RES 180R SMD 5 0W25 1206 1 C56 0681 003 CPCTR DCPLR 100n SMD 1210 1 R532 0521 820 RES 82R SMD 5 0W25 1206 1 C57 0610 010 CPCTR TANT 10u 10V 20 1 R533 0521 331 RES 330R SMD 5 0W25 1206 1 C58 0681 003 CPCTR DCPLR 100n SMD 1210 1 R534 0521 680 RES 68R SMD 5 0W25 1206 1 C59 0681 001 CPCTR DCPLR 33n SMD 1210 1 R535 0521 680 RES 68R SMD 5 0W25 1206 1 C60 0635 470 CPCTR ALEC 47u 16V RAD 1 R536 0521221 RES 220R WO 5 0W25 1206 1 C61 0635 230 CPCTR ALEC 220u 16V RAD 1 R537 0521 680 RES 68R SMD 5 0W25 1206 1 C62 0640 473 CPCTR CER 47n 30V 80 1 R538 0521 221 RES 220R SMD 5 0W25 1206 1 C63 0635 470 CPCTR ALEC 47u 16V RAD 1 R539 0521 680 RES 68R SMD 5 0W25 1206 1 C64 0681 001 CPCTR DCPLR 33n SMD 1210 1 R540 0521 221 RES 220R SMD 5 0W25 1206 1 C65 0642 103 CPCTR ALEC 100u 25V RAD 1 R541 0521 680 RES 68R SW 5 OW25 1206 1 C66 0635 230 CPCTR ALEC 220u 16V RAD 1 P542 0521 221 RES 220R SMD 5 0W25 1206 1 C67 0635 047 CPCTR ALEC 4u7 16V RAD 1 R543 C68 0640 473 CPCTR CER 47n 30V 80 1 R546 0521 102 RES 1 KO SMD 5 0W25 1206 4 C69 0635 230 CPCTR ALEC 220u 16V RAD 1 R547
39. Dx4THK 1 R40 0521 103 RES 10K SMD 5 0W25 1206 1 3 pare LABEL ermano 1 o 40 0890 013 FOOT S A RUBR 8Dx2 5Hmm 2 R43 0521102 RES 1KO SMD 5 OW25 1206 1 R44 0521 472 RES 4K7 SMD 5 0W25 1206 1 per batch R45 0521 562 RES 5K6 SMD 5 0W25 1206 1 R46 0521 681 RES 680R SW 5 0W25 1206 1 R47 0521 100 RES 10R SW 5 0W25 1206 1 R48 0521 122 RES 1K2 SMD 5 0W25 1206 1 R49 R65 0521 680 RES 66R SMD 5 0W25 1206 17 R66 0521 331 RES 330R SMD 5 0W25 1206 1 R67 R71 0521 220 RES 22R SMD 5 0W25 1206 5 R72 R75 0521 472 RES 4K7 SMD 5 0W25 1206 4 R76 0521 562 RES 5K6 SW 5 OW25 1206 1 R77 0521 681 RES 660R SMD 5 0W25 1206 1 R76 0521 100 RES 10R SMD 5 0W25 1206 1 R79 0506 250 RES 332R MF 1 0W25 E96 1 R80 0521 330 RES 33R SMD 5 0W25 1206 1 R61 0521 332 RES 3K3 SMD 5 0W25 1206 1 R82 0507 223 RES 22K MF 1 0W25 1 R83 0506250 RES 332R ME 1 0W25 E96 1 R84 0521 560 RES 56R SMD 5 0W25 1206 1 R85 0521 332 RES 3K3 SMD 5 OW25 1206 1 R86 0507 223 RES 22K MF 1 0W25 1 R87 0521 680 RES 68R SMD 5 0W25 1206 1 Main PCB fault diagnosis amp repair 51 3000 Service Manual Item Part no Description Qty Item Part no Description Qty R88 0521 332 RES 3K3 SMD 5 0W25 1206 1 R562 N F R89 0521 332 RES 3K3 SMD 5 0W25 1206 1 R563 N F R90 0521 560 RES 56R SMD 5 0W25 1206 1 R564 0521 473 RES 47K SW 5 OW25 1206 R91 0507 223 RES 22K MF 1 OW25
40. ETE and outputs a message to the printer This indicates that the A3000 computer has passed all the non subjective tests However the message Tests Complete should NOT necessarily be interpreted as a PASS since you may wish to fail the computer on one of the subjective tests If a failure has been found during the non subjective tests the screen displays a FAILED message and lists the failures on the printer assuming that the printer is functioning and that you did not select the All Tests Except Printers option from the menu Insert the Test Disc and press space to return to the main menu 41 3000 Upgrade tests To test Upgrades fitted to the computer follow the procedure detailed at the start of the Main functional test section for loading and running the software then select option 2 from the main Dealer Test Menu The Upgrades menu will appear A3000 Upgrades Test Menu 1 Midi 2 1M Byte Memory 3 RS232 4 Main Menu SELECT OPTION Introduction Type in the number of the test you wish to run ifit fails substitute a known good upgrade If the test still fails replace the main PCB or see the next chapter for repair information A3000 User Port MIDI Upgrade Introduction The UPM Upgrade functional test should be carried out whenever you install repair or replace a UPM Upgrade The suite of programs provide assistance when fault finding by providing continuous looping Note The MIDI Th
41. K7 LK30 LK28 LK29 LK31 LK6 20 Yes Yes INo Yes Yes Yes Yes Yes Yes Not Not Not Not No Connection point for left channel audio speaker P1 OV P2 signal Connection point for right channel audio speaker P1 OV P2 signal Connection point for an external battery Only used if supply of on board NiCad becomes a problem Used in conjunction with LK19 to select size of ROM devices Used in conjunction with LK20 to select size of ROM devices ROM LK19 LK20 512K 2 3 2 3 1M 2 3 2 3 1 2 2 3 1 2 1 2 2M 4M Used to configure P5 of SK14 RGB Video Socket to be either VSync or Mode Fit shunt for VSync NF shunt for Mode Mode is required by some SCART TVs Used to configure P4 of SK14 RGB Video Socket to be either HSync or CSync Shunt 1 2 for HSync Shunt 2 3 for CSync Used to invert VSync Shunt fitted VSync Shunt NF VSync Used to invert HSync Shunt fitted HSync Shunt NF HSync Test point for Non Volatile Memory clock frequency P1 OV P2 32 768KHz Used in conjunction with LK29 and LK28 amp 31 on Iss1 to provide the necessary signals for a Genlock interface circuit P1 VS P2 HS P1 Ckvidc P2 Clksys P1 0V P2 Sink P1 Sup P2 0V Test point for Non Volatile Memory battery voltage P1 OV P2 1 2V 0 2V None None None Shunt 2 3 Shunt 2 3 ie 1M Shunt NF
42. OME 3 2D amp THK USE ON ITEM 6 RES ZERO R 0W25 RES 21 2 C MF 5 0W25 RES 21 2 C MF 5 0W25 RES 220R C MF 5 OW25 RES 220R C MF 5 OW25 RES 220R C MF 5 OW25 RES 220R C MF 5 OW25 RES 1K0 C MF 5 0W25 RES 2K2 C MF 5 0W25 RES 2K2 C MF 5 0W25 RES 220R C MF 5 OW25 RES 10K C MF 5 0W25 RES 10K C MF 5 0W25 CPCTR 220u ALEC 16V RAD CPCTR DCPLR 33 47n 0 2 IC 65C22 VIA CMOS 2MHz OPTO ISOL 6N138 8 0 3 ROM 0727 128 9 TBP IC 7406 TTL 14 0 3 IC 2691 UART CMOS 24 0 3 IC 74HC139 CMOS 16 0 3 DIODE 1N4148 SI CONR 20W HDR IDC RA 4WALL CONR SW SKT DIN RA PCB CONR 5W SKT DIN RA PCB CONR 5W SKT DIN RA PCB CONR 17W WAFR 0 1 23 5mmL CONR 17W WAFR 0 1 23 5mmL a 020 A eo A I A A R a Es A m LA 22 N F a ai a A La Main PCB fault diagnosis 8 repair 3000 Service Manual Appendix A Serial port loopback plug Serial port loopback plug direction of copper strips hole components join above the board surface H Parts list Assembly notes Assemble the components onto Veroboard and fit item Item Part no Description Qty 5 the shell to protect the assembly 1 0276 081 CIRCUIT 8 ASSEMBLY DRAWING 1 3 0800 288 CONR 9W SCKT D ST MS SB 1 5 0800 991 CONR 9W SHELL D SCREWS 1 R1 0502 122 RES 1K2 C MF 5 0W25 1 R2 0502 122 RES 1K2 C MF 5 0W25 1 R3 0502 122 RES 1K2 C MF 5 0W25 1 R4 0502 122 RES 1K2 C MF 5 0W25 1 R5 0502 472 RES
43. PCB If this passes then replace the MIDI podule under test or else replace the main PCB 1 Mbyte DRAM Expansion Test Selecting m Byte Memory from the Upgrades test menu runs the memory upgrade test which records its progress on the screen 1 Mbyte Dram Expansion Test one incrementing pattern two TRUE hierarchy three FALSE hierarchy four Cycling bits PASSED FAILED message Press SPACE to continue Fault diagnosis 3000 Action if test falls If the computer fails the test restart the system with a delete power on and run the test again If the test still fails check the connection between the main PCB and the memory expansion card If test fails yet again try a known working memory card If this fails then replace the main PCB else replace the faulty memory card RS 232 test When it has been selected this test will automatically run and give a PASSED or FAILED message Action If the test fails make sure that the configuration items BAUD and DATA are set to sensible values BAUD 4 and DATA 4 for example If the test still fails after you have ensured that the loopback plug is functional on another unit change the main PCB A diagram for the loopback plug is included in the Appendices Fault diagnosis Service Manual 43 A 3000 44 Service Manual Fault diagnosis 3000 Service Manual Main PCB fault diagnosis amp repair Introduction This chapter deals w
44. UST be programmed HIGH to select normal operation of the chip Allows the state of the parallel printer acknowledge input to be inspected This bit MUST be programmed HIGH to select norma operation of the the chip This controls he muting of the internal speaker It is programmed HIGH to mute the speaker and LOW to enable it The speaker is muted on reset Available on the Auxiliary VO connector Reserved and should be programmed HIGH Used as the floppy disc READY input and must be programmed HIGH The C 0 1 pins are used to implement the bi directional serial I2C bus to which he Real Time Clock and battery backed RAM are connected and Test Mode PACK amp Test Mode 12 Service Manual System description A3000 The sound system The sound system is based on the VIDC stereo sound hardware External analogue anti alias filters are used which are optimised for a 20 kHz sample rate The high quality sound output is available at a 3 5mm stereo jack socket at the rear of the machine which will directly drive personal stereo headphones or alternatively an amplifier and speakers Two internal speakers are fitted to provide stereo audio VIDC sound system hardware VIDC contains an independent sound channel consisting of the following components A four word FIFO buffers sixteen 8 bit sound samples with a DMA request issued whenever the last byte is consumed from the FIFO
45. VER 1 R11 0521 102 RES 1 KO SMD 5 0W25 1206 1 17 0280 073 BLANKING PANEL 1 R12 0521 472 RES 4K7 SMD 5 0W25 1206 1 18 0260 074 LOCK PLATE 2 R13 0521 472 RES 4K7 SW 5 0W25 1206 1 19 0260 075 CABLE RESTRAINT PLATE 4 R14 0521 331 RES 330R SMD 5 0W25 1206 1 20 0260 077 PSU COVER 1 R15 0521 222 RES 2K2 SMD 5 0W25 1206 1 21 0280 078 PSU INSULATION SHEET 1 R16 23 0480 041 BBC LED LABEL 1 R24 0521 220 RES 22R SW 5 0W25 1206 9 24 0480 042 BASE LABEL 1 R25 25 0480 043 NO SERIAL LABEL 1 R28 0521 472 RES4K7 SW 5 0W25 1206 4 26 0480 044 REAR MAINS LABEL 1 R29 0521 102 RES 1K0 SW 5 0W25 1206 1 27 0480 047 ACORN LOGO LABEL 1 R30 0521 472 RES 4K7 SMD 5 0W25 1206 1 29 0860 024 GMAT CBL RND 7 4Dx4T BLK 1 R31 0521 472 RES 4K7 SMD 5 0W25 1206 1 30 0940 007 ADH HOT MELT AIR R32 0521 103 RES 10K SMD 5 0W25 1206 1 31 0882 770 SCW No2x1 4 PLST PAN POS 1 R33 0521 103 RES 10K SMD 5 0W25 1206 1 32 0882 716 SCW No4x1 4 PLST PAN POS 2 R34 0521 331 RES 330R SW 5 0W25 1206 1 33 0662 111 SCW M2 5x6 PAN HD POSI 4 R35 0521 331 RES 330R SW 5 0W25 1206 1 34 0662 121 SCW M3x6 PAN HD POSI 4 R36 0521 102 RES 1K0 SW 5 0W25 1206 1 35 0862 711 SCW No4x3 4 PLST PAN POS 1 R37 0521 104 RES 100K SMD 5 0W25 1206 1 36 0682 730 SCW No6x3 8 PLST PAN POS 1 R36 0521 104 RES 100K SMD 5 0W25 1206 1 37 0882 971 WSHR M2 5 SPRF IT STL 2 R39 0521 104 RES 100K SMD 5 0W25 1206 1 38 0884 048 RIVET PLST DOME 3 1
46. amp 18 and shunts fitted to LK17 and 18 from 1000251 Fixing of 64W connector Two rivets Avdel 11070312 were added to the mounting holes of the 64 way expansion connector Design changes made between Issue A and Issue 1 PCBs Serial interface The strapped on resistor see above was replaced by a permanent resistor 10K SMD 5 R144 Signal conditioning R141 R142 and R143 have been added 22R SMD 5 to REF8M RA9 and IORQ R134 has been moved to accomodate these A capacitor C116 2n7 has been added between SW3 and OV Video genlocking LK28 amp 29 tracks have been deleted see above LK 28 29 amp 30 moved LK31 has been added This allows access to the VIDC supremacy bit pin 28 and GND JEDEC amp non JEDEC EPROMs The tracks between the pins of LK17 amp 18 have been deleted see above 23 A 3000 RGB amp SYNC A 6 way connector LK32 not fitted has been added to RGB amp SYNC for internal access Production changes The components R550 C55 C78 C500 C501 and C504 have been moved to facilitate production R145 4K7 SMD 5 has been added between 1C2 pin 31 and 5V to accomodate ATE Test points have been added to the following lines ARM20 MEMC3 MEMC38 MEMC39 MEMC40 MEMC41 MEMC42 R129 R132 have been moved to accomodate these test points 24 Service Manual System description 3000 A3000 expansion Internal expansion DANGER DANGEROUS VOLTAGES
47. an Econet module External expansion 1 Follow the procedure in the next chapter for removing the cover of the computer Interface 2 Plug the module onto the PCB connectors introduction The A3000 computer supports an external expansion card podule interface although with some minor differences from other ARM based systems Single 5Volt power supply rail rated at a maximum of 1 Amp no 12 or 5 Volt rails provided No support for Co Processor type cards The external expansion card is in software slot 0 The podule must be capable of driving 3 TTL and 7HCT loads on the data bus Refer to the application note A series podules referenced at the start of this chapter for a full podule interface specification Physical dimensions As the podule is external to the computer enclosure there is no real limit on the size of the unit Care should be taken not to block off any of the other expansion ports on 3 Replace the cover of the computer 4 Run the dealer test software to test the correct the rear of the computer function of the computer and the Econet module SE i and of any other upgrades fitted Refer to the Fitting an expansion card appropriate Econet file server Manager s Guide for instructions on setting the station id WARNING Power down the computer before fitting or removing an external expansion card It is anticipated that expansion cards will be fitted into a suitable external expansion
48. ator Service Manual The mapping of the BD 0 15 bus onto the D 0 31 bus is as follows During a WRITE ie ARM to peripheral D 16 31 is mapped to BD 0 15 During a READ ie peripheral to ARM BD 0 15 is mapped to D 0 15 Byte accesses To access bytewide expansion cards byte instructions are used A byte store instruction will place the written byte on all four bytes of the word and will therefore correctly place the desired value on the lowest byte of the I O bus A byte or word load may be used to read a bytewide expansion card into the lowest byte of an ARM register Half word accesses To access a 16 bit wide expansion card half word instructions are used When storing the half word is placed on the upper 16 bits D 16 31 To maintain upwards compatibility with future machines half word stores replicate the written data on the lower half word D 0 15 When reading the upper 16 bits are undefined Expansion card identification It is important that the system is able to identify what expansion cards if any are present and where they are This is done by reading the Podule expansion card Identification PI byte or bytes from the Podule Identification Field Hex address 3FFFFFF 3800000 DMA address generators ROM low Video Controller Input Output Controllers Physically mapped RAM Logically mapped RAM System description 3600000 3400000 3000000 2000000 0000000
49. card unit Slots are provided underneath the case of the computer into which a tongue in the case of the expansion card unit can locate Tapped holes are provided in the backplate of the computer to enable the expansion unit to be secured to the computer with two M6 screws Connector The podule interface is provided via a 64 way DIN A C 41612 socket fitted at the rear of the computer O M6 screw holes Connector viewed from the back of the computer The connections to the interface are shown overleaf A3000 expansion 29 A 3000 Service Manual External expansion connections Pin ROWA ROW C Row C description OV OV Ground LA 15 reserved LA 14 OV Ground LA 13 OV Ground LA 12 reserved LA 11 MS 0 MEMC Podule select LA 10 reserved LA 9 reserved LA 8 reserved LA 7 reserved LA 6 reserved LA 5 FIST Reset see note below LA 4 PR W Read not write LA 3 PWE Write strobe LA 2 PRE Read strobe BD 15 PIRQ Normal interrupt BD 14 PFIQ Fast interrupt BD 13 S 6 BD 12 C 1 12C serial bus clock BD 11 C 0 12C serial bus data BD 10 S 7 External Podule select BD 9 PS 0 Simple Podule select BD 8 IOGT MEMC Podule handshake BD 7 IORO MEMC Podule request BD 6 BL VO data latch control BD 5 OV Supply BD 4 CLK2 2MHz Synchronous clock BD 3 CLK8 8MHz Synchronous clock BD 2 REF8M 8MHz Reference clock BD 1 5V Supply BD 0 reserved 5V reserved o NO O1 R ND
50. ceed 10 seconds No waiting period between tests is necessary Main PCB fault diagnosis amp repair
51. circuits on PACK and PBSY on pins 2 and 4 of 1C9 and 11 and 13 of IC8 If the data printed is incorrect check the continuity of the data lines into and out of IC 11 though the series resistors and onto SK 10 If both the printer and the floppy disc drive fail change IC 18 Capacitors C23 to C33 on the printer port occasionally go open circuit These should be checked if printer problems are being experienced Serial port upgrade Check that the upgrade has been correctly installed Make sure that the configuration items BAUD and DATA are set to sensible values Check for 10V on IC7 pin 1 and 10V on pin 24 Check for the clock on IC 1 pins 6 and 7 change X1 if faulty f OK change IC1 and IC7 50 Service Manual Expansion cards Run the relevant expansion card test if it fails substitute a known good expansion card f the test still fails check through System failure tracing all signals through to the expansion card socket SK15 external or SK3 and 11 internal f necessary replace expansion card backplane Power down the computer before fitting or removing an external expansion card Main PCB fault diagnosis 8 repair 3000 Service Manual Parts lists PCB assembly parts list The parts lists in this chapter detail the components used in the manufacture of the computer and its upgrades Contact the Spares Department of Acorn item Fees Des ription Qty Computers Limited accou
52. ck the disc drive ID switch is set to the correct position normally 0 for single floppy drive 1 for second floppy drive Swap the cable and drive for known good examples Check power to to drive If fault persists change the main PCB Fault diagnosis Service Manual RS 232 Ensure the A3000 RS232 test plug is fitted before carrying out this test see the Appendix for details Action if the test fails make sure that the configuration items BAUD and DATA are set to sensible values Baud 4 and Data 4 for example If the test still fails after you have ensured that the loopback plug is functional on another unit change the main PCB or carry out the Serial socket checks in the next chapter Printer If one of the printer options was set a test pattern is sent to the printer The pattern comprises a repeated series of stepped lines each representing bits O to 7 You should look for missing or corrupted pattern As this is a subjective test make a note of any faults that you detect Action If test fails if the test fails with a known good printer and cable connected check the configuration settings for PRINTER and GNORE are correct If the fault still persists change the main PCB or see the next chapter for repair information On completing the tests On completing the tests the screen displays TESTS COMPLETE TESTS COMPLETE TESTS COMPLETE TESTS COMPLETE TESTS COMPLETE TESTS COMPL
53. ds to be held down for several seconds The screen should display the DESKTOP environment Note A useful indication of the success of the delete power on sequence is the momentary appearance of a red border area on the screen Insert the Test disc Hold down Ctrl Shift and then press Break The program will load from disc The Dealer Test Menu is displayed A3000 Dealer Test Menu 1 Main Computer 2 Upgrades Load Save CMOS RAM Soak Test Quit SELECT OPTION Machine identification test Select the option Main computer After selecting and loading the required test program the A3000 computer cycles through a series of tests beginning with the computer type model test This test is extremely fast and the type and model number of the computer is displayed immediately This computer is a BBC A3000 CHECK DESCRIPTION THEN PRESS lt SPACE gt TO CONTINUE You should 1 Check that the description displayed on the screen is correct 2 If unknown uur is displayed then there is a memory fault Action If test falls Change the main PCB or see the next chapter for 38 Service Manual repair If an RS232 or 1Mb RAM upgrade is fitted but not mentioned switch off the unit under test remove the upgrade and then continue the test When the computer has passed the main test sequence power down the unit and re install the upgrade and then run the relevant upgrade test If the description is the same p
54. e appropriate The mask registers are undefined after power up The IRO events are split into two sets of registers A and B There is no priority encoding of the sources Internal Interrupt Events Timer interrupts TM 0 1 e Power on reset POR e Keyboard Rx data available SRx Keyboard Tx data register empty STx e Force interrupts 1 External Interrupt Events IRQ active low inputs IL 0 7 wired as 0 7 respectively PFIQ SIRQ SLC1 NOT USED DCIRQ PIRQ PBSY and RII e IRQ falling edge input IF wired as PACK e IRQ rising edge input IR wired as VFLY e FIQ active high inputs FH O 1 wired as FFDQ and FFIQ FIQ active low input FL wired as EFIQ Control port C 3 5 10 Service Manual IRO status A 7 6 5 4 3 2 1 0 E Fro ve ron ve pacs w Jessy Printer Busy Input Serial line ring indicator input Printer acknowledge input Video vertical flyback Power on reset Timer 0 Timer 1 Force IRQ interrupt This bit indicates that the printer is busy This bit indicates that a Ringing Indication has been detected by the serial line interface This bit indicates that a printer acknowledgement bit has been received This bit indicates that a vertical flyback has commenced This bit indicates that a power on reset has occurred These bits indicate that events have occurred Note latched interrupt This bit is used to force an IRQ request it is usually o
55. e computer power off check for about 1 1 V on IC6 pin 8 If this voltage is not present check R3 and R7 If less then 1V change the battery B1 and check the operation of D2 and C15 If the NVM IC6 consistently fails on the same data bits change the device If the clock fails to run or runs inaccurately check and if necessary replace X2 LK7 allows access to the clock signal 49 3000 Peripheral faults Keyboard and mouse Make sure that the configuration items DELAY and REPEAT are set to sensible values see the A3000 User Guide Check computer interface by swapping to a known good keyboard or mouse Floppy disc drive Make sure that the configuration items STEP and FLOPPIES are correctly set Check that the disc drive ID selection switch is in the zero position Swap the disc drive for a known good drive and cable f this also fails check the power supply connection for 5 V and 0 V If the computer is not recognising the drive check that all cables are connected both to the drive and to the PCB and that power is present on the power cable Also check that the drive ID plate has not fallen off inside the drive and jammed it Printer Make sure that the configuration items for IGNORE and PRINT are set to sensible values Swap the printer for a known good printer and cable If the printer fails completely check for a STROBE signal on Q1 collector trace back through R36 and IC18 Also check for shorts or open
56. e frame for registration ACORN and ECONET are trademarks of Acorn Computers Limited IBM is a trademark of International Business Machines Corporation Within this publication the term BBC is used as an abbreviation for British Broadcasting Corporation Published September 1989 Published by Acorn Computers Technical Publications Department Part number 0480 050 Issue 1 A 3000 Contents System description Introduction General The I O system The sound system The keyboard and mouse Floppy disc drive Power supply Links Plugs Sockets Changes between Issue A and Issue 1 PCBs A3000 expansion Internal expansion External expansion Disassembly and reassembly Fault diagnosis Introduction Checking a dead computer Functional tests Main computer tests Upgrade tests Main PCB fault diagnosis amp repair Introduction System failure Video faults Peripheral faults Test ROMs Parts lists Appendix A Serial port loopback plug Appendix B Earth continuity testing Drawings A3000 final assembly diagram User Port MIDI circuit diagram Internal upgrade diagram External podule fixing diagram Main PCB circuit diagram Main PCB top assembly diagram Main PCB bottom assembly diagram bound separately Service Manual 43000 Service Manual A SUUU System description Introduction The A3000 computer is built around the ARM chip set comprising the Acorn Risc Machine ARM itself the Memory Co
57. entres to 2 Mb by the addition of a 1Mb RAM module which 1 Follow the procedure for removing the cover of the puso themain FCB computer given in the next chapter Fitting a RAM upgrade 1 Follow the procedures detailed in the next chapter for the removal of the computer cover and the keyboard 2 Unscrew the two machine screws holding the rear blanking plate in place and remove the plate 2 To fit earlier RAM upgrades with securing lugs remove two PCB retaining screws and plug the upgrade module in a vertical position into the board Later upgrades with no fitting lugs simply push into the connectors on the PCB 3 Plug the expansion card into the connectors on the PCB and press firmly home 3 Replace the screws securing the PCB and the upgrade module 4 Replace the keyboard and the cover of the computer 5 Run the dealer test software to test the correct function of the computer and the upgrade and of any other upgrades fitted CARD CONNECTORS 4 Replace the two screws holding the expansion card backplate and secure firmly 5 Replace the cover of the computer 6 Run the dealer test software to test the correct function of the computer and the upgrade and of any other upgrades fitted Keep the rear panel blanking plate with the computer in case the expansion card is removed later A3000 expansion 27 A 3000 Serial port upgrade Introduction The A3000 computer is fitted with a 9 wa
58. fails the subjective tests It is a good idea for testers to familiarise themselves with the correct results given by a known good computer In this way they will be ina better position to judge faulty results Performing soak tests At the successful completion of a main PCB functional test you should carry out a soak test To do this select the relevant option and then insert the scratch disc when prompted The test runs for 12 hours When the test is running the Caps Lock and Num Lock LEDs will flash provided that no error has occurred If a disc error occurs all the LEDs will be off see table below the disc error is also displayed on the screen If the test is completed without an error then the Scroll Lock LED will flash and the Caps Lock and Num Lock LEDs will be extinguished Num Lock Caps Lock Scroll Lock Screen Flashing Error Off Off Finished Off Off No errors Flashing Warning Flashing Running Fail Pass During the soak test the unit under test should not be subjected to mechanical shock or movement The unit shall not be turned off unless the test has terminated the pass or fail message will be displayed Safety check After repairing a unit and after the soak test you should carry out the earth continuity check mentioned at the start of the chapter followed by a further run through of the functional test in case the earth check causes malfunction in the computer
59. gnal does no exceed 3HCT gates or that stated in A Series podules Any upgrade must be able to drive at least 7 HCT and 3 TTL loads on the data bus Power supply The maximum power available from the 5V rail is 600 mA The maximum dissipation inside the case is 0 5W 100mA Mechanical The rear panel required is shown in the drawing at the back of this manual The size of the User Port MIDI expansion card PCB and position of the connectors are also shown in the drawing at the back of the manual User port MIDI expansion card UPM Introduction The A3000 User Port MIDI expansion card fits inside the computer and provides An 8 bit User Port largely compatible with the User Port interface on the BBC Model B and Master 128 microcomputers and with the User Port on the Archimedes I O expansion card MIDI Musical Instrument Digital Interface with IN OUT and THRU connections compatible with the International MIDI Association specification Main components 65C22 VIA for the User Port 2691 UART for the MIDI 27128 EPROM containing firmware and ID byte 25 3000 UPM block diagram Service Manual Addresses of main system components Address amp 0000 1FFC DATA BUS Comparison with Archimedes expansion cards ARCHIMEDES 1 0 EXPANSION CARD The VIA is at the same address and clocked at the same speed Port A PA lt 0 2 gt is used to page ROM These are the same as the UPM when set
60. gnal through the periphery circuitry and out to SK14 where the voltage on R G and B should be the same Audio Test the audio with both headphones and internal speakers Do not forget to issue SPEAKER ON and VOLUME 127 commands if required making sure that the sound modules are active see the No sound Main PCB fault diagnosis 8 repair Service Manual algorithm in the previous chapter If either of the speakers fail but the headphone socket functions normally check connections to the main PCB via LK22 and LK23 and check IC32 or 1C38 pin 5 for a signal of 2 3 V amplitude If no signal is present on pin 5 but can be found on pin 3 change IC32 or 38 Check continuity through R76 and R45 and check that 1C13 pin 49 is not stuck high If there is no audio at all first check for 5 V on both ends of L19 fthis is open circuit check the condition of C108 before replacement Check for about 3 V on VIDC IC41 pin 12 f there is no voltage or a different one check R500 C107 and C108 A low amplitude signal should be found on VIDC 1C41 pins 13 14 15 and 16 f not change VIDC These signals can be traced through the peripheral circuitry and out to 011 and 012 The signal amplitude at these points should be about 1 3 V pk to pk Check for short or open circuit on signals SNDAK and SNDRQ on VIDC 1C41 pins 9 and 24 Configuration NV memory and RTC If the NVM suffers data retention problems and the RTC fails then with th
61. he known good mouse to isolate the fault to either the keyboard or the mouse Replace faulty components then retest If everything is normal the program moves on automatically to the next test Keys The screen clears to show a representation of the keys in the main keyboard area You need to test each key in turn in the correct order ie work from the bottom line of the keyboard and from left of the keyboard to the right 1 Press Caps Lock 2 Check that the picture of the Caps Lock key disappears from the screen 3 Press Alt and check that the picture of the Alt key disappears from the screen If the picture of the key does not disappear from the screen then leave a small delay before pressing the next key If the screen stops clearing the characters as you press the keys go back to the lowest leftmost key remaining on the screen and start again from there 4 Continue working along the bottom line Then start working from left to right along the next line up Note If you accidentally press two keys together you will see both keys displayed on the screen You should press Break to continue If the same fault occurs repeatedly or the picture of the depressed key refuses to disappear then it will be IMPOSSIBLE to continue the test You should replace the keyboard and start the whole test again Fault diagnosis 3000 5 When all keys in the main keyboard area have been pressed successfully the screen clears and di
62. in Signal I Ded 6 Dsr 2 Rxd 7 Rts 3 3 Txd 8 Cts Notes 4 Dtr 9 Ri t Fitted to Issue 1 PCBs 5 OV Socket diagrams are viewed from outside the computer System description 21 A300 Sockets contd No Fitted Function Specification RGB Video Socket 9 way D type socket providing an interface to analogue RGB monitors and Scart TVs Links 24 25 26 amp 27 can be used to alter the polarity and type of synchronisation signals present to suit a vanety of monitors RGB Video levels 0 7V Pk Pk into 75 Ohm Sync Voltage levels gt 2 0V TTL 5 4 3 2 1 OOO 0 0 0 0 9 8 7 6 Signal IBM PC PGA pinning Red Monochrome Video Output Phono socket providing a monochrome composite video signal of 1V Pk Pk 0 7V video 0 3V Sync into a 75 Ohm load Negative sync positive video Stereo Headphone Output 3 way 3 5mm stereo jack socket providing output to personal stereo type 32 Ohm stereo headphones uput voltage 1V Pk Pk into 32 Ohm External Podule Expansion 64 Way DIN41612 socket providing an interface connection to a single host powered extemal Podule This Podule may be a MemC or Simple type but not a Co processor For a full spec of this interface see the chapter headed A3000 expansion Parallel Printer Port 25 way D type socket providing a parallel printer interface 13 12 11 10 9 8 7 6 5 4 3 2 1 0000000000000 000000000000 25 24
63. information only The VO system System description 14 3000 System architecture The I O system which includes expansion card devices consists of a 16 bit data bus BD 0 15 a buffered address bus LA 2 21 and various control and timing signals The I O data bus is independent of the main 32 bit system data bus being separated from it by bidirectional latches and buffers In this way the 1 0 data bus can run at much slower speeds than the main system bus to cater for slower peripheral devices The latches between the two buses and hence the I O bus timing are controlled by IOC IOC caters for 4 different cycle speeds slow medium fast and synchronous A typical A3000 I O system is shown in the diagram on the previous page For clarity the data and address buses are omitted from this diagram System memory map The system memory map is defined by the MEMC and is shown below Note that all system components including I O devices are memory mapped I O space memory map This IOC controlled space has allocation for simple expansion cards and MEMC expansion cards Data bus mapping The I O data bus is 16 bits wide 8 bits wide for the internal expansion card interface Bytewide accesses are used for 8 bit peripherals The 1 0 data bus BD 0 15 connects to the main system data bus D 0 31 via a set of bidirectional data latches System memory map Read Write Logical to Physical ROM high address transl
64. ith fault diagnosis and repair of the main PCB at component level See the previous chapter for basic fault diagnosis before proceeding to this chapter Tools required The suggested tools for fault diagnosis and repair of the A3000 PCB are as follows e 100 MHz oscilloscope DC voltmeter Earth continuity tester see Appendix B Chip extraction tools 68 84 pin Soldering desoldering workstations capable of handling both conventional and surface mounted devices Standard handtools It is a recommended requirement that anti static precautions should be utilised at all levels of servicing ie antistatic matting and wrist straps Main PCB fault diagnosis amp repair DANGER AFTER REFITTING OR FITTING A REPLACEMENT ASSEMBLY CARRY OUT EARTH CONTINUITY TESTING ON THE ASSEMBLED COMPUTER ACCORDING TO THE PROCEDURE GIVEN IN APPENDIX B WARNINGS e Repairs to multi layered PCBs The main PCB is a four layer board Components should only be removed from the board using equipment specifically designed for this purpose For details of suitable equipment available contact Acorn Customer Service e Repairs to surface mounted devices The ARM MEMC IOC AND VIDC ICs on the A3000 PCB are surface mounted components Do not attempt to remove them from the board and replace them unless you are appropriately trained in surface mount technology and have the correct equipment to do so f in doubt contact Acorn Customer Services
65. ll be taken high and the internal speakers will be muted The stereo output to the headphone socket is not muted by SMUTE and will always reflect the current output of the DAC channels 13 AA 3000 The keyboard and mouse The Keyboard and mouse connection to the ARM is via a keyboard controller and a serial link to the IOC The ARM reads and writes to the KART registers in the IOC The protocol is essentially half duplex so in normal operation the keyboard controller will not send a second byte until it has received an ACK The only exception to this is during the reset protocol used to synchronise the handshaking where each side is expecting specific responses from the other and will not respond further until it has those In addition to this simple handshaking system the keyboard controller will not send mouse data unless specifically allowed to as indicated by Ack Mouse which allows the transmission of one set of accumulated mouse coordinate changes or the next move made by the mouse While it is not allowed to send mouse changes the keyboard controller will buffer mouse changes A similar handshake exists on key changes transmitted as key up and key down and enabled by Ack Scan At the end of a keyboard packet two bytes the operating system will perform an Ack Scan as there is no protocol for re enabling later Mouse data may be requested later by means of Request Mouse Position ROMP Key codes The keyboa
66. llowing efficient use of paged mode DRAM without locking the system data bus for long periods MEMC supports Direct Memory Access DMA operations with a set of programmable DMA Address Generators which provide a circular buffer for Video data a linear buffer for Cursor data and a double buffer for Sound data The Input Output Controller IOC controls the I O bus and expansion cards and provides basic functions such as the keyboard interface system timers interrupt masks and control registers It supports a number of different peripheral cycles and all I O accesses are memory mapped A SUUU VIDC takes video data from memory under DMA control serialises it and passes it through a colour look up palette then converts it to analogue signals for driving the CRT guns VIDC also controls all the display timing parameters and controls the position and pattern of the cursor sprite In addition it incorporates an exponential Digital to Analogue Converter DAC and stereo image table for the generation of high quality sound from data in the DRAM VIDC is a highly programmable device offering a very wide choice of display formats The colour look up palette which drives the three on chip DACs is 13 bits wide offering a choice from 4096 colours or an external video source The cursor sprite is 32 pixels wide and any number of rasters high Three simultaneous colours again from a choice of 4096 are supported and any pixel can be
67. lts in the A3000 computer system It consists of algorithms to enable you to trace amp remedy faults in a dead computer followed by instructions for running the functional test software designed to isolate faults in a computer which is working The next chapter Main PCB fault diagnosis and repair is designed to help those repair centres equipped to do so to diagnose and repair faults at component level on the main PCB Test equipment required 100 MHz oscilloscope DC Voltmeter Earth Continuity tester Serial port loopback plug part number 0280 087 See the Appendix for details of the plug 32 ohm impedance headphones IC extraction tools Antistatic matting and wrist straps Standard hand tools Fault diagnosis service Manual DANGER AFTER REFITTING OR FITTING A REPLACEMENT ASSEMBLY CARRY OUT EARTH CONTINUITY TESTING ON THE ASSEMBLED COMPUTER ACCORDING TO THE PROCEDURE GIVEN IN APPENDIX B je WARNINGS Repairs to multi layered PCBs The main PCB is a four layer board Components should only be removed from the board using equipment specifically designed for this purpose For details of suitable equipment available contact Acorn Customer Service Repairs to surface mounted devices The ARM MEMC IOC AND VIDC ICs on the A3000 PCB are surface mounted components Do not attempt to remove them from the board and replace them unless you have the experience and the correct equipment to do so
68. mine the exact device that is faulty by examining the corruption pattern on the display The default memory size is amp 100000 bytes 1 Mbyte however this may be cycled through 0 5 1 2 and 4 Mbyte memory sizes by pressing the M key When using the ROMs on a machine having memory content other than 1 Mbyte the video display may at first appear out of line or incorrect In this instance press the M key repeatedly until the required memory size has been selected The memory test is cyclic and on completion of each full memory test a full stop will be displayed until it completes one line of the screen The next completed cycle will move the lefthand full stop down one pixel and then in sequence across the screen The 0 5 Mbyte test takes between 3 and 4 seconds to complete whilst the 4 Mbyte test takes about 29 seconds If for some reason the video display is completely blank or unreadable eg because of a video fault a printed output may be obtained by selecting option 1 the output being produced at the printer port as well as on the VDU If an error is found in the memory the display will show AT ADDRESS amp nnnnnnnn WROTE amp pppppppp READ XXXXXXXXXXX The message will be displayed on one line where nnnn is the faulty address pppp is the data written to that address and xxxxxxxx is the data read back from that address in binary form The least significant bit is the righthand bit The memory tests do not termi
69. n memory If no sound or sound from one speaker only then check speaker connections If it still fails substitute known good speakers and re test If the sound comes from one speaker only check that the headphone plug is inserted correctly If test still fails replace the main PRESS lt SPACE gt TO CONTINUE PCB or carry out the Audio test in the next chapter and repair as necessary Checking read write function of BBR Re loading configuration parameters PASSED FAILED message Press the Space Bar to continue the test To continue with the test press the space bar Action if test falls Check battery and connections and check battery is charged Re run the test if the test still fails replace Headphones the main PCB or see the NVM and RTC tests in the next chapter and repair as necessary The Functional test continues by testing the operation of the headphones The following message is displayed as the test proceeds Time The functional test continues by testing the time and date settings A series of options is displayed on the HEADPHONE MES TE RONNANS screen LISTEN AND CHECK SOUND THEN PRESS lt SPACE gt TO CONTINUE DO YOU WANT TO The test consists of a repeating sequence of eight musical notes The first four notes are played on one headphone and the next four notes on the other 1 CHECK THE DATE AND TIME headphone 2 SET THE DATE AND TIME 3 CHECK THEN SET THE DATE AND TIME 1 Put on the headpho
70. nate unless an error is found in which case after reporting 8 or 9 errors the test will terminate Any error will have a cascading effect so it is good practice to repair the first error displayed first Note An additional check is made on the state of CMOS RAM control lines CO and C1 at the beginning of the test before the display If either of these lines are short circuit to 0 Volts the Test ROMs will indicate this on power up 47 Memory map Physical Address IC Numbers amp 2000000 IC21 1C20 amp 2000001 1022 1C23 82000002 IC24 1C25 82000003 IC26 IC27 repeat until amp 20FFFFF 8 2100000 to amp 21FFFFF upgrade Repetitive reset test This section of test code is intended for use when the main memory test menu fails to initialise To make use of this section of the ROMs the following test equipment is required Oscilloscope Signal or pulse generator The purpose of the code is to produce certain signals around specific areas of the PCB These signals may then be monitored using the oscilloscope to assess the operation of that area of the circuit Repetitive reset test assembler listing Service Manual A suitable square wave or preferably a negative going pulse generator output at 10 kHz should be connected to the reset line via a component connected to SKT3 pin 13 After setting the border colour to white the signals should be observable in the following order which checks the output
71. ne byte response in reset protocol RQPD 0100 XXXX One byte from ARM encodes four bits of data PDAT 1110 XXXX One byte from keyboard echoes four data bits of RQPD RQID 0010 0000 One byte ARM request for keyboard ID KBID 10xx XXXX One byte from keyboard encoding keyboard ID KDDA 1100 XXXX New key down data Encoded Row 1st byte and column 2nd byte numbers KUDA 1101 XXXX Encoded Row 1st byte and column 2nd byte numbers for a new key up RQMP 0010 0010 One byte ARM request for mouse data MDAT Oxxx XXXX Encoded mouse count X byte1 then Y byte2 Only from ARM to keyboard BACK 0011 1111 Ack for first keyboard data byte pair NACK 0011 0000 Last data byte ack selects scan mouse mode SACK 0011 0001 Last data byte ack MACK 0011 0010 Last data byte ack SMAK 0011 0011 Last data byte ack LEDS 0000 Oxxx Bit flag to turn LED s on off PRST 0010 0001 From ARM one byte command does nothing x is a data bit in the Code e g xxxx is a four bit data field System description 15 A 3000 the enable function of SACK and MACK While key scanning is suspended after NACK or MACK any new key depression is ignored and will not result in a key down transmission unless the key remains down after scanning resumes following a SACK or SMAK Similarly a key release is ignored while scanning is off Commands may be received at any time Therefore commands can be interleaved with acknowledge replies from the ARM For example keyboa
72. nes PRESS 1 OR 2 OR 3 2 Listen to the sequence of notes 3 This is a subjective test so if you detect any deviation in either headphone note down the fault The normal procedure is to select option 1 If you want to reset the time or date you would select 2 or 3 For Action if test falls example you can If no sound or poor faulty sound on known good 1 Type 1 to check the date and time headphones replace the main PCB or carry out the 2 Check that the time is correct and the seconds are Audio test in the next chapter and repair as incrementing correctly necessary Ensure the headphones are plugged in 3 To continue with the test press the Space Bar correctly To continue with the test press the Space Bar Loudspeaker The functional test continues by testing the operation of Standard colour monitor the loudspeakers A short repeating sequence of four notes is played first through the left and then the right speaker The following message is displayed This test consists of a series of screen displays You proceed through the test at your own pace The first display consists of a series of white lines radiating from the top lefthand corner A cursor in the shape of a bird travels across the screen starting from the bottom left and finishing at the top right The LOUDSPEAKER TEST features to check are LISTEN AND CHECK SOUND THEN PRESS lt SPACE gt TO CONTINUE e the accuracy of the lines the movement and integrit
73. nt holders only or its 4 0260 000 BARE PCB 4 authorised dealers and Approved Service Centres for 2 0160 000 A AVON PCB ASSEMBLY DWG q information as to which parts are available as spares 3 0180 000 0 AVON PCB CIRCUIT DIAGRAM 1 6 0280 072 PCB BACK PANEL 1 9 0800 070 CONR 2W SHUNT 0 1 10 FITTED TO LK17 20 24 29 Fi bl t li t 10 0800 126 SKT IC 24 0 3 NORM IC7 1 11 0800 128 SKT IC 28 0 6 NORM IC1 1 inarassem y par S IS 12 0600 132 SKT IC 32 0 6 SUPA IC14 17 4 13 0800 140 SKT IC 40 0 6 NORM 1 15 0870 422 WIRE 25SWG CPR TIN A R inti X1 X2 X3 Feeney Description aty 17 0902 004 LABEL SERIAL PCB 15x50mm 1 19 XXXX XXX RIVET AVDEL 11070312 SKIS 2 1 0060 000 A FINAL ASSEMBLY DRAWING 1 A cree A en AH 1 R1 0521 102 RES 1K0 SW 5 0W25 1206 1 5 0276 106 RESET BUTTON 1 R2 0521 102 RES 1 KO SMD 5 0W25 1206 1 7 0180 000 AVON MAIN PCB ASSY 1 R3 0521 181 RES 160R SMD 5 0W25 1206 1 8 0180 010 22W 240V PSU 1 R4 0521 331 RES 330R SMD 5 0W25 1206 1 9 0160 011 KEYBOARD UK 1 R5 0521 271 RES 270R SMD 5 OW25 1206 1 10 0180 012 MAINS CABLE ASSY 1 R6 N F 11 0180 081 SPEAKER ASSEMBLY 2 R7 0521 181 RES 160R SMD 5 0W25 1206 1 12 0183 004 3 5x1 1MB DISC DRIVE 1 R6 0521 101 RES 100R SMD 5 0W25 1206 1 14 0260 061 LOWER MOULDING 1 R9 0521223 RES 22K SMD 5 0W25 1206 1 15 0260 062 UPPER MOULDING 1 R10 0521 472 RES 4K7 SMD 5 0W25 1206 1 16 0260 063 BATTERY CO
74. ntroller MEMC Video Controller VIDC Clock NVM Keyboard interface The ARM IC is a pipelined 32 bit reduced instruction set microprocessor which accepts instructions and manipulates data via a high speed 32 bit data bus and 26 bit address bus giving a 64 Mbyte uniform address space The ARM supports virtual memory systems using a simple but powerful instruction set with good high level language compiler support MEMC acts as the interface between the ARM the Video and 1 0 Controllers Read Only Memory ROM and Dynamic memory devices DRAM providing all the critical system timing signals including processor clocks 1 or 2 Mbyte of DRAM is connected to MEMC which provides all signals and refresh operations A Logical to Physical Translator maps the Physical Memory into a 32 Mbyte Logical address space with three levels of protection allowing Virtual Memory and Multi Tasking operations to be implemented Fast page mode DRAM General System description Address Bus m R E Net A Serial E Imerial Disc Parallel upgrade upgrade extemal B printer upgrades VO Address Bus Service Manual and Input Output Controller IOC A block diagram of the A3000 is shown below Data Bus VO Data Bus accesses are used to maximise memory bandwidth VIDC requests data from the RAM when required and buffers it in one of three FIFOs before using it Data is requested in blocks of four 32 bit words a
75. or use under repetitive reset To install the test ROMs carefully remove the RISC OS ROM set ICs 14 15 16 and 17 and replace them with the test ROMs 1 2 3 and 4 respectively crystal RA Front of computer The test ROMs use the bare minimum of hardware to run the system remove disconnect all peripherals not needed for the tests although a keyboard is needed A printer can also be connected if required Main memory test Providing that the ARM MEMC and VIDC are functioning the test ROMs will auto boot into the menu driven display below At any point in the operation of the test ROMs pressing the RESET key or re powering the machine will re start the program and re display the menu 012345678 9012345678901234567890123456789012345678901234 Al DIAGNOSTIC TEST ROMS MEMORY SIZE 0XX00000 BYTES 1 CYCLIC MEMORY TEST WITH PRINTOUT 2 CYCLIC MEMORY TEST SELECT The memory test checks memory according to memory size selected It is possible that faulty memory may lie in the region Main PCB fault diagnosis amp repair Service Manual designated as screen memory f this occurs the video display may become unreadable For this reason the sequence 0123456789 is repeated across the top line of the display Every 4 digits represent a 32 bit word Watch for missing or corrupted display As the start of the screen memory is known to be at physical address amp 2000000 it should be possible to deter
76. otocol The mouse keys are allocated unused row and column codes within the main key matrix Row code 7 Column code 0 Row code 7 Column code 1 Row code 7 Column code 2 Switch 1 left Switch 2 middle Switch 3 right For example switch 1 release would give 11010111 D7 hex as the complete row code followed by 11010000 DO hex for the column code Note Mouse keys are disabled by NACK and MACK acknowledge codes and are only enabled by SACK and SMAK codes ie they behave in the same way as the keyboard keys The mouse is powered from the computer 5 V supply and may consume up to 100 mA Movement signals Each axis of movement is independently encoded in two quadrature signals The two signals are labelled REFerence and DlRection e g X REF and X DIR The table below defines the absolute direction of movement Circuitry in the keyboard decodes the quadrature signals and maintains a signed 7 bit count for each axis of mouse movement Increase count by one for each change of state Decrease count by one for each change of state O00aa OO m 2200 O When count overflow or underflow occurs on either axis both X and Y axis counts lock and ignore further mouse movement until the current data has been sent to the ARM Overflow occurs when a counter holds its maximum positive count 0111111 binary Underflow occurs when a counter holds its maximum negative count 1000000 binary
77. ower on reset occurs A user reset occurs A protocol error is detected After sending HRST the keyboard controller waits for a HRST code Any non HRST code received causes the keyboard controller to resend HRST The pseudo program below illustrates the reset sequence or protocol set mouse mode to data only in response to an RMPS request stop key matrix scanning and set key flags to up send HRST code to ARM Wait for next code IF code RAK1 THEN send RAK1 to ARM Wait for next code IF code RAK2 THEN send RAK2 to ARM Wait for next code IF code ELSE IF code SACK THEN enable key scanning ELSE error ELSE error ELSE IF code MACK THEN set mouse mode to send when not zero ELSE IF code NACK THEN do nothing ELSE error END reset Reset sequencing SMAK THEN mouse mode to send if not zero and enable key scan Direction Code Expected Action on Action on Action if reply wrong reply timeout unexpected Sender Sender Receiver ARM gt kb Hard reset Hard reset Resend Resend Hard reset Kb gt ARM Hard reset Reset Ack 1 Resend Nothing Hard reset ARM gt Kb Reset Ack 1 Reset Ack 1 Hard reset Hard reset Hard reset Kb gt ARM Reset Ack 1 Reset Ack 2 Nothing Nothing Hard reset ARM gt Kb Reset Ack 2 Reset Ack 2 Hard reset Hard reset Hard reset 14 System description A 3000 Note the on off state of the LEDs does not change across a reset event hence the LED state is not defined at power on The ARM is always
78. placed underneath the PSU and that the the cover is correctly located Take care not to overtighten the self tapping screws Removing the PCB 1 Follow the procedures above for the removal of the cover the keyboard floppy disc drive and the 1MByte RAM if fitted 2 Remove the power leads at the point where they connect to the PCB red 5V and black OV 3 Disconnect the two speaker leads and remove the RH speaker viewed from the front 4 Unscrew the three self tapping screws retaining the PCB and the PCB and rear panel will lift out of 32 Service Manual the case Fitting is the reverse of the above procedure insert the PCB into the clips at the front edge of the case before lowering into place Care should taken to ensure that the RESET key is not damaged Replacing the battery The battery providing current to the real time clock and battery backed RAM is soldered to the PCB If this needs replacing it will have to be removed using a soldering iron and a desoldering gun Repair sites lacking the equipment and experience in this type of work should not attempt to carry it out or damage to the PCB may result Care should be taken to avoid shorting the battery connecting the positive and negative terminals even on a battery being discarded Disassembly and reassembly A SUUU Fault diagnosis Introduction This chapter is a guide to the diagnosis and repair of basic fau
79. rd controller identifies each key by its row and column address in the keyboard matrix Row and column codes are appended to the key up or down prefix to form the complete key code For example Q key down the complete row code is START reset ON error Send HRST code to ARM then wait for code from ARM IF code HRST THEN restart ELSE error ON restart clear mouse position counters Service Manual 11000010 C2 hex and the column code is 11000111 C7 hex Note Eight keys have N key roll over The operating system is responsible for implementing two key roll over therefore the keyboard controller transmits all key changes when enabled The keyboard controller does not operate any auto repeat only one down code is sent at the start of the key down period Data protocol Data transmissions from the keyboard are either one or two bytes in length Each byte sent by the keyboard controller is individually acknowledged The keyboard controller will not transmit a byte until the previous byte has been acknowledged unless it is the HRST code indicating that a power on or user reset occurred or that a protocol error occurred see below Reset protocol The keyboard controller restarts when it receives a HardReSeT HRST code from the ARM To initiate a restart the keyboard controller sends a HRST code to the ARM which will then send back HRST to command a restart The keyboard controller sends HRST to the ARM if A p
80. rd sends KDDA 1st byte keyboard receives command keyboard receives BACK keyboard sends KDDA 2nd byte keyboard receives command keyboard receives SMACK If the HRST command is received the keyboard immediately enters the restart sequence ON restart The LEDS and PRST commands may be acted on immediately Commands which require a response are held pending until the current data protocol is complete Repeated commands only require a single response from the keyboard ARM commands Mnemonic Function Reset keyboard Tums key cap LEDs on off A three bit field indicates which state the LEDs should be in Logic 1 is ON logic 0 zero OFF DO controls CAPS LOCK D1 controls NUM LOCK D2 controls SCROLL LOCK Request mouse position X Y counts Request keyboard identification code The computer is manufactured with a 6 bit code to identify the keyboard type to the ARM Upon receipt of ROID the keyboard controller transmits KBID to the ARM Reserved for future use the keyboard controller ignores this command For future use The keyboard controller will encode the four data bits into the PDAT code data field and then send PDAT to the ARM 16 Service Manual Mouse interface The mouse interface has three switch sense inputs and two quadrature encoded movement signals for each of the X axis and Y axis directions Mouse key operations are debounced and then reported to the ARM using the Acorn key up key down pr
81. ress the space bar to continue to the next test Test options TEST OPTIONS A AllTests Except Printer B AllTests and Epson Printer C AllTests and JP101 Printer SELECT OPTION Select the test appropriate to the printer fitted If you do not want to test the printer and do not need a printout of the results you can select the All Tests Except Printer option Memory The functional test continues by testing the memory The screen clears and displays the following messages Memory test Phase one incrementing pattern Phase two TRUE hierarchy Phase three FALSE hierarchy Phase four Cycling bits 4 4 PASSED FAILED message Press SPACE to continue A failed message will end the tests Action if test falls Change the main PCB or run the main memory test in the next chapter and repair as necessary If the test has PASSED press the Space Bar to continue the test Fault diagnosis 43000 Service Manual You should Battery backed RAM 1 Listen to the sequence of notes The test continues by testing battery backed RAM 2 Check that the first four notes come from the left The following message is displayed on the screen speaker and the second four from the right 3 Check that the sound produced is correct This is a subjective test so if you detect any deviation make a note of the fault Battery Backed Ram BBR test running Action if test falls Reading BBR into mai
82. ru port is NOT tested Equipment required In order to carry out the test you will require the following equipment UPM Upgrade to be tested which should have been installed A3000 Computer e 3 5 inch Test Disc write protected e Monochrome or analogue RGB monitor e Acorn Econet cable User port loopback plug wired as in the diagram below Dual trace oscilloscope if you are fault finding 2 20 oooo0oo0oo0oo0o0o0 00 1 19 UPM Upgrade loopback plug 20 way IDC 42 Service Manual Connecting the equipment Connect the Computer to the monitor MIDI IN socket to the MIDI OUT socket using the Econet cable e User port loopback plug to the User port Monitor to the mains supply e A3000 to the mains supply Running the test When you have selected miai from the Upgrades menu the UPM test menu will appear A3000 UPM UPGRADE DEALER TESTS 1Functional test 2Functional test soak 3Services routines Enter choice Select the appropriate test from the menu all tests load automatically Selections 1 and 2 give a PASSED or FAILED message Selections 3 gives a further choice after which a Running message indicates that the selected routine is functioning and the associated signals can be traced with an oscilloscope Action if test falls Check that the test leads are working and are plugged into the correct sockets if the test still fails then try using a known working
83. splays a diagram of the rest of the keyboard area Again press each key in turn following the guidelines above 6 When all the keys have been successfully pressed the screen dears and displays the following message MOUSE TEST PASSED MAIN KEYBOARD TEST PASSED NUMERIC KEYPAD TEST PASSED PRESS RESET BUTTON TO END TEST Press the RESET button on the side of the unit You have now finished the keyboard functional test Action if tests fall Make sure that the configuration items DELAY and REPEAT are set to sensible values such as Delay 32 and Data 4 see the User Guide for details If the keyboard PCB is replaced re run the keyboard functional test Floppy disc drive The Floppy disc drive test consists of two parts The first part of the test checks the write protect mechanism The test disc must be write protected for this test to work If the A3000 disc drive passes the following message is displayed FLOPPY DISC DRIVE TESTS Checking write protect PASSED Write Protect Insert Scratch Disc Then press SPACE Replace the Test disc with an ADFS D format write enabled disc the scratch disc Any data already on this disc may be destroyed so it is best to use a blank formatted disc The test continues with disc Read Write and Erase tests Each test gives a PASSED FAILED message Action if test falls If the test fails check that the configuration for STEP and FLOPPIES is correct Che
84. te as follows programming a 19 bit address into the PNTR register sets the physical address from which sequential DMA reads will occur in multiples of four words and programming the END pointer sets the last physical address of the buffer Whenever the PNTR register increments up to this END value the address programmed into the START register is automatically written into the PNTR register for the DMA to continue with a new sample buffer in System description Service Manual memory A Sound Buffer Interrupt SIRQ signal is generated when the reload operation occurs which is processed by IOC as a maskable interrupt IRQ source The Memory Controller also includes a sound channel enable disable signal Because this enable disable control signal is not synchronised to the sound sampling requests will normally be disabled after the waveforms which are being synthesised have been programmed to decay to zero amplitude the last value loaded into the Audio data latch in the VIDC will be output to each of the Stereo image positions at the current Audio Sample rate IOC sound system hardware IOC provides a programmed output control signal which is used to turn the internal speaker on or off as well as an interrupt enable status reset register interface for the Sound Start Buffer reload signal generated by MEMC The internal speakers may be muted by the control line SMUTE which is driven from the IOC output C5 On reset this signal wi
85. ults Video failure 1 Check for 5 V on both ends of L18 If open circuit then check C100 for a short circuit Replace L18 and C100 as appropriate Also check for 3 5 Volts approx on IC 41 pin 43 Should this not be present then check R109 D16 and C93 2 Check for a 24 MHz clock on IC41 pin 19 f missing then check continuity to and through LK28 and R138 3 Check for video data on 1C41 pins 39 40 and 41 f not present check power supply to 1041 4 Check for short circuits on signals VIDRQ and VIDAK 5 Check connection of all data lines to VIDC IC 41 6 Finally change 1C41 Unstable or scrolling display The computer may have lost its configuration value for SYNC Type at the keyboard CON SYNC 1 RETURN Press reset RESET and see if if any change occurs Investigate configuration failure Check for CSYNC signal on SK14 pin 4 If not present trace back through LK24 R535 and IC40 finally changing VIDC 1041 Check settings of LK24 and LK27 see Links table Corrupted display If the display breaks up around its edges and spurious characters appear then investigate the system oscillator Suspect IC470r X3 Check DRAM using the memory test routines Colours incorrect or missing With a full white screen VIDC 1C41 pins 39 40 and 41 should all have the same signal on them f not check pin 43 which should show approximately 3 5V if not check R109 C93 and D16 Finally change VIDC 1C41 Trace each si
86. unction with LK15 Trk 1 2 LK15 No to select the keyboard uC Trk 1 2 device type ie NMOS Device Type LK14 LK15 8051 NMOS 12 1 2 80051 CMOS O C 2 3 PRZ Ne Provides access to RGB inter NF face signals Issue 1 only 1 Red 4 VCSYNCH 2 Green 5 VSYNC MODE 3 Blue 6 0V Notes NF Not Fitted P1 Pin 1 0 C Open Circuit Trk Tracked Active low t Fitted on Issue 1 PCB System description A 3000 Service Manual Sockets Plugs ae see Function Specification No Fitted Function Specification PL5 N Floppy Disc Power Connector If the Mouse Port power to the disc drive is to be supplied 9 way MiniDin socket providing interface via the data cable then PL5 must be fitted to a standard Acom Archimedes style and the PSU free disc power socket must mouse be connected to this plug with LK21 P1 NC P2 OV P3 OV P4 5V PL6 No Floppy Disc Drive Data Connector 34 way Box Header containing all the signals required by the internal floppy disc drive This interface is identical to that of the Pin Archimedes except that the drive strength 1 X direction reference of some of the signals has been reduced 2 Switch 1 as only one drive is supported The pin 3 Switch 2 numbering has been altered due to the 4 OV incorrect orientation of the Archimedes 5 X direction layout 6 5V 7 Y direction reference Default powering is via a separate power 5 Swich a connector from the PSU ie not up the
87. upply Performance characteristics Performance Min Nom Max Units Input voltage 47 53 Hz 198 220 240 264 Vac Input voltage 57 63 Hz 99 115 130 Vac Output voltage VO1 49 b 5 1 Vdc Output current 101 05 44 Amps dc Output ripple and noise VO1 50mV pk pk BW 0 50MHz Overshoot VO1 0 1Vdc Over voltage plot VO1 thrshld 5 8 7 0 Vdc Surge output current 101 F H 5 8 Amps dc Surge output current duration H 1 0 Sec Efficiency 65 max ld Total output power F H 22 Watts cont 29 Watts srge Input voltage is selected by means of a link wire connected either to the pin marked 240 on the left hand side of the power supply when facing the front of the computer or to the pin marked 120 in the top centre of the PSU If the input voltage is changed it is strongly recommended that a label indicating the new voltage to which the computer has been set is fixed to the outside of the case A mains plug appropriate to the new supply should also be fitted to prevent the computer from being powered up at the wrong voltage DANGER DANGEROUS VOLTAGES ARE EXPOSED INSIDE THE CASE OF THE COMPUTER WHEN THE COVER IS REMOVED THE COMPUTER SHOULD BE DISCONNECTED FROM THE MAINS SUPPLY BEFORE THE COVER IS REMOVED Floppy disc power connector 19 Links Service Manual Link Fitted Effect Default LK22 LK23 LKS LK20 LK19 LK25 LK24 LK27 LK26 L
88. wned by the FIQ owner and is used to downgrade FIQ requests into IRQs Printer Ack Vert Flyback Power on reset Timer 0 and Timer 1 events Force System description 3000 IRQ status B Podule FIQ req Snd buftr swap Serial line ctrir H disc interrupt Disc changed interrupt Pod interr req Keyb Tx event Keybd Rx event System description Podule FIQ request Sound buffer reload request Serial line controller interrupt Winchester interrupt request Disc changed interrupt request Podule IRQ request Keyboard Serial Tx event Keyboard Serial Rx This bit indicates that a Podule FIQ request has been received It should usually be masked OFF This bit indicates that the MEMC sound buffer pointer has been relocated This bit indicates that 65C51 serial line contolier interrupt has occurred This bit indicates that a hard disc interrupt has occurred This bit indicates that the floppy disc has been removed This bit indicates that a Podule IRQ request has occurred This bit indicates that the keyboard transmit register is empty and may be reloaded This bit indicates that the keyboard reception register is full and may be read Service Manual Interrupt status FIQ 7 6 5 4 3 2 1 0 Pro x x x era Fria Froa Floppy disc data request Floppy disc interrupt request Econet interrupt request See OC datasheet
89. y D type serial connector on the back panel but this is not functional until a serial port upgrade kit has been fitted by an Acorn Dealer or Approved Service Centre Only Acorn Serial Port Upgrade kits should be used The A3000 serial port upgrade consists of a serial processor chip and a line driver chip which fit into existing sockets on the PCB Connector pinouts Service Manual Fitting the Acorn A3000 serial port upgrade 28 WARNING It is a recommended requirement that anti static precautions should be utilised at all lev els of servicing ie antistatic matting and wrist straps 1 Follow the procedures in the next chapter for the removal of the cover and the keyboard 2 Remove the Econet module and the User Port MIDI expansion card if fitted 3 Insert the 28 pin IC 65C51 into socket IC1 and the 24 pin IC LT1133 into socket IC7 The notched ends of the ICs should face towards the left hand side of the PCB viewed from the front of the computer 4 Fit the serial number label to the PCB near the upgrade ICs 5 Refit any modules and expansion cards removed in step 2 above and replace the cover of the computer 6 Remove the label Serial not fitted from the rear panel 7 Run the dealer test software to test the correct function of the computer and the serial port and of any other upgrades disturbed during this installation A3000 expansion 43000 Service Manual Fitting
90. y of the cursor Fault diagnosis 39 43000 This is a subjective test so make a note of any faults When you have finished looking at the screen display press the Space Bar to move to the next display The next screen displays consist of four test cards There is a test card for each of the three colour guns and a grey scale to test the three guns The four test cards are e Red scale Green scale e Blue scale e Grey scale Each test card consists of 16 concentric circles beneath a horizontal band which is divided into 16 sections A pale border highlights the left most eight sections of the band in order to distinguish the band from the background The whole test card is surrounded by a contrasting border The purpose of the cards is to display 16 shades with the shade of the border as the middle of the range You should observe the 16 shades displayed the mid coloured border the quality of the grey scale display e the integrity of each test card This is a subjective test so make a note of any faults which you detect and when you are ready to continue press the Space Bar Action If test falls if display rolls or is unstable perform a Delete Power on until the correct default value is obtained The computer may have lost its configuration value for SYNC Type at the keyboard CON SYNC 1 RETURN Press RESET and see if if any change occurs If no improvement is visible change the main PCB

A3000 Service Manual

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