Corvus Mirror Service Manual
Contents
1. MM M nn n M CORVUS DEALER SERVICE SYMPTOMS TIMES OUT continued NO IMAGE FOUND FAULTS OUT POSSIBLE CAUSE Bus direction improper Mirror not enabled No Startbit No SYNC pulse Phi Baud No STROBE signal No stop bit Tape position error Low quality damaged or worn tape Backup not good No input to Mirror from VCR Video input circuit defective Bus direction improper Mirror not enabled No Startbit No SYNC pulse Phi Baud No STROBE signal No stop bit VISYNC defective 6MB microswitches set improperly DATA CONTROL line shorted CRC chip generating errors SYNC signal bad TROUBLESHOOTING PROCEDURE Check TP 10 for proper signal Should be high during record and toggling during playback Check TP 9 for low signal Check TP 5 for proper signal Check TP 11 for high signal Check TP 7 for proper signal Check TP 12 for proper signal Check TP 6 for proper signal Perform quick check 5 Replace video tape and retry operation Perform Verify operation If Verify not successful redo backup Perform quick check 5 to check signal from VCR Check TP 3 for proper signal Check TP 10 for proper signal Should be high during record and toggling during playback Check TP 9 for low signal Check TP 5 for proper signal Check TP 11 for high signal Check TP 7 for proper signal Check TP 12. CORVUS DEALER SERVICE MIRROR COMPUTER INTERFACE BI DIRECTIONAL BUS FOD A200 VIDEO CASSETTE RECORDER DISK DRIVE Figure 4 System Block Diagram The data is transmitted on a bi directional 8 bit parallel bus whose direction is controlled by the bus direction The READY signal is provided by the controller to let the interface know that the data is ready on the bus The interface responds with a strobe when the data is accepted and the controller then negates the ready signal When the controller is reading the data the ready line indicates that the controller is ready to accept the data and the STROBE from the Mirror indicates the validity of the data on the bus The Error Correction hardware in the interface is controlled by three lines the CRC Generator the CRC Preset and the CRC Data Select line The CRC Generator monitors the bit stream of the data being recorded and generates a checksum that is added to the block that follows the data The CRC Preset initializes the state of this generator prior to the transmission at the beginning of the data At the end of the data transmission the CRC Data Select line is placed in the CRC mode in order that the Checksum data is transmitted onto the video signal On playback the bit stream is fed into the CRC generator and the Error Status line verifies the validity of the data following the reception of the data and the CRC bytes The SYNC lin
3. DM8304 U5 15299 U6 09275 EF Yr Ye AADDCB 3163 A CIR QA SU IN4i48 I5wvDC Ble Tie Tu 7 EET 1511413121917 1 12 13 14 15 16117 18 213112 k q5 7 C7 READY 3 Eur 13 E B LM3I9 ISW READY Cs E 2 TPS dm ve pia 12 K STROBE V Y SYNC SYNC 4 sraosEG2 29 V XTI 4 31818 MHz STARTBIT STOPBIT STARTBIT STOPBIT a 6574 SYNC X 13 UI6 10 12 20 Ul4 10 a 2 ALTREAD 2 4 9 Y 8 14 8 ACTIVE NOTES UNLESS OTHERWISE SPECIFIED CAPACITANCE VALUE IN MICROFARAD 11 18 2 ALL RESISTANCE VALUE IN OHMS dBAUD CORVUS SYSTEMS para 8 10 81 aver MIRROR 10 20 MB SCHEMATIC DKAWING 0010008 waman r 27 REVISIONS PCO DESCRIPTION DATE TATREL FOR PROD p oe d E BL EA 69 101 gt 3 3 ps 99 gt 030587 EBD en II p CT 02 O Ili visync m Di EEE NE a A La BEER MERE E eee LI De 95 m 1504 L Bo BUS o ALT SEL g dd AT SELC GZ woe BUS DIR A l READY 93 I NINE VIDEO iN em TRI w Ve Ri 10 14 31818 MHZ al 202222 ES es 4 VIDEO QUT STARTBIT STARTBIT a un o lt 5 no sm v
4. CORVUS SYSTEMS INC LASTUSED USED APPROVATI reo avam ar 3 78 cre ALL RESISTANCE VALUES ARE IN OHMS 52 SSL IC 2 SMB MIRROR _ NOTES UNLESS OTHERWISE SPECIFIED K W 40010007 28
5. Z 80 and Z 80A are registered trademarks of Zilog Inc FCC WARNING This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause interference to radio communications As temporarily permitted by regulation it has not been tested for compliance with the limits for Class A computing devices pursuant to Subpart J of Part 15 of FCC Rules which are designed to provide reasonable protection against such interference Operation of this equipment in a residential area is likely to cause interference in which case the user at his own expense will be required to take whatever measures may be required to correct the interference CORVUS DEALER SERVICE CORVUS SYSTEMS MIRROR SERVICE MANUAL CORVUS DEALER SERVICE MIRROR MANUAL TABLE OF CONTENTS CHAPTER 1 MIRROR OVERVIEW 1 0 Scope ob Chapter iero een eles Meat anna ato i epa En Rel een ac ees 1 11 Introduction to the Corvus Mirro s Co em esse 1 1 2 Computer Compatibilities ee here 1 1 3 Video Recorder Compatibilittes ann means 2 1 4 Video Tape ompatibilities su di gern 2 CHAPTER 2 FUNCTIONAL DESCRIPTION 2 0 Scope of Chapter tai xn a huy ee ame er 4 2 1 Mirror Technical Overview reni saa nee ee nee rede 4 2 2 Video Formats saksasqa Ed ASS A 5 2 3 External Signals si uate Ng uy ee FL dev ce u ea 6 2 4 Component Intera
6. buffering allows for separation of blocks to avoid burst errors overlapping two blocks A buffer at the end of the visible portion is necessary as the tapehead leaves the tape at the bottom of the visible portion in order to ensure that it reads a good vertical retrace signal When the headleaves the tape no data can be recovered so another buffer is used which isolates that time from the data blocks The Video Timing Generator provides line and frame synchronization for the processor during record The first block of data is transmitted following the vertical retrace and data is output through the IJO port into the shift register where it is converted from parallel to serial form The data is then output from the IJO port at which time the handshake occurs and the startbit is transmitted The data byte is shifted out and at which time a stop bit is added This data stream is summed with the SYNC output of the video timing generator and level shifted to create the final video signal output The playback mode is essentially the inverse of record As video signals are input to the interface the SYNC information is separated and sensed by the microprocessor The data bit stream is extracted by comparing the signal to a reference voltage halfway between the black and white signal levels As the signal goes positive the startbit is triggered and the microprocessor begins to sample the data stream at intervals corresponding to the bit
7. controller with timing information that is relevant to the beginning of the horizontal lines as well as retrace between video fields The SYNC signal and the data stream are added together by the Video Summing Circuit before being output to the video recorder This circuit also provides standard analog levels On playback the SYNC and the data stream are extracted from the signal The input analog signal is restored along with the horizontal retrace pulses These pulses are also separated from the signal to provide the SYNC lines The data stream is recovered by comparing the video signal to the reference voltage midway between the black and white levels The Control State Machine provides the state controls for the Mirror interface The operation is similar for both the record and playback modes The initial WAIT state is ended with a READY startbit in record In record mode a strobe is sent tosignal the acceptance of data The next state either skips or generates the data startbit After 8more data clock states data is shifted either into or out of the shift register Another idle state follows which produces or skips the stop bit In the final state a strobe is sent to represent the valid data in the shift register The controller then returns to a WAIT state The Shift Register is the heart of the data path When in the record mode the shift register is parallel loaded and data is then shifted out following the start bit During playba
8. default is No Compare Records You may request the computer to compare all records after a restore has been attempted by selecting this option The computer will do a byte by byte comparison of the test image and the restored data The computer will then report any miscomparisons The default is Yes 18 CORVUS DEALER SERVICE Display Bad Bytes This option allows you to view the results of any failed comparisons on a byte by byte basis The computer will display the source and destination byte as well as relative sector and byte locations 4 2 2 SUM Option The SUM Summary option displays the cumulative results of the tests executed All errors will be logged and accumulated from the time the program is started or the last zero 4 2 3 TST Option The TST option will start the test which you have selected from the parameters menu You have the option of specifying the number of times the test is to be repeated 4 2 4 ZERO Option f The ZERO option will zero the test counters so that the results of the previous test will not be added into the results of future tests NOTE The following four options are visible from the menu by pressing the question mark key 425 IMG Option With the IMG option you can do a backup without automatic verify or restore The image recorded will follow the same parameters set up in the PRM option 4 2 6 RES Option You can restore a recorded image under test using the RES option Unde
9. synchronization errors as CRC faults Each block is made of 107 lines with each line containing 5 bytes of information stored as a serial bit stream Oh HORIZONTAL LINE gt gt START BITS OV t STOP BITS HORIZONTAL HORIZONTAL RETRACE DATA LEVELS Figure 3 Video Signal Figure 3 depicts the analog signal that is recorded as a line of data One data is a high voltage white level and zero data is the black level Horizontal retraces are triggered by video pulses below the black level indicating the line boundaries for Television Video Standards Due to the high bandwidth and the necessity to interrupt data transmission during horizontal and vertical retrace START STOP serialization was implemented The start of each byte was preceded by the transmission of a high level bit and following the byte a low level bit is transmitted START STOP while having a high overhead does provide better noise immunity and simpler circuitry to allow bit synchronization to an asynchronous non continuous data stream 2 3 External Signals The Mirror is controlled via the Data Bus Ready Strobe SYNC Alternate Select Bus Direction and the SYNC The Mirror interface responds to these lines and generates a video signal that can be recorded by a VCR converts a video signal provided by the VCR into digital data to be stored onto the drive a a a a ur
10. the integrity of the data on the drive It is very likely that there are media defects on the drive if disk errors are encountered Compare errors indicate that the data recorded did not match the data restored If this occurs check to make sure that you have not changed the parameters of the test between the time that you performed backup and restore Also the restore address must be greater than or equal to the sum of the starting address and the number of blocks per pass If this is not true a miscompare will result If a miscompare results due to a real failure the most likely cause will be the link between the controller and the Mirror Note that the computer interface card is on the same parallel data bus and can also be the culprit CORVUS DEALER SERVICE 4 4 0 MIRDIAG Error Codes The following is a list of error codes that may be encountered during the operation of the MIRDIAG program MIRROR ERRORS Error Code Description File ID mismatch Invalid restore command Invalid retry command File size mismatch Invalid opcode Start of image not found Position error Tape dropout during playback WOON AF OQ N gt 20 CORVUS DEALER SERVICE AGA CHAPTER 5 TROUBLESHOOTING CORVUS DEALER SERVICE CHAPTER 5 MIRROR TROUBLESHOOTING 5 0 Scope of Chapter This chapter will serve to guide you through troubleshooting the Corvus Mirror inte
11. to find the last error Because the errors are relative short bursts it is unlikely that the bursts would overlap so that the companion block would likely have good data Reconstruction of the block is possible because the CRC bytes will indicate good data At this point the first and last error position are averaged and this position is used as a breakpoint for the reconstruction of a good block The first block is transmitted through the CRC checker up to the breakpoint then the remaining data is transmitted from the second block If the bursts were masked the CRC checker will indicate valid data if not the transmission order is reversed and the burst will be masked out and the data recovered 2 6 Record Operation Initially the interface is in an idle state as the SYNC pulses from the video timing generator are transmitted to the external interface controller With the R W line in the WRITE mode the data stream is selected from the shift register by the Data CRC select signal see Figure 6 Data is placed on the bus and the READY line is set high by the external controller where it is then parallel loaded in the shift register A STROBE pulse is returned to the external controller and then a Startbit is sent out of the state machine This Startbit is added to the video sync signal to produce a white signal Following a Phi baud clock pulse the Startbit is set low and the first bit of data is output serially to the video sum circuit T
12. 0 2622 for NTSC format and 2621 for PAL SECAM format Check TP 10 for proper signal Should be high during record and toggling during playback Perform quick check 5 Replace video tape and retry operation Clean VCR record and playback heads Perform Verify operation If Verify not successful redo backup Check TP 15 for proper signal If not okay see schematic Check TP 16 for proper frequency Check 1 amp TP 2 for proper signal If not Okay see schematic Check for shorts on U6 between pins 16 4 15 5 14 6 13 and 7 Also check for defec tive chips on data control line Check ICs on DATA COMMAND lines U5 and U6 are common failures Check TP 3 for proper signal Check TP 10 for proper signal Should be high during record and toggling during playback Check TP 9 for low signal Check TP 5 for proper signal Check TP 11 for high signal Check TP 7 for proper signal Check TP 12 for proper signal Check TP 6 for proper signal Replace VCR 25 TEST POINT N O O da 0 MIRROR TEST POINTS SIGNAL NAME SERIAL DATA IN SERIAL DATA OUT VIDEO IN RESET STARTBIT STOPBIT PHI BAUD VISYNC ENABLE BUS DIRECTION SYNC STROBE ALT SEL VIDEO FREQUENCY CRC OSCILLATOR LOCATION CHIP PIN U6 18 U6 8 U9 4 U3 1 08 11 08 10 027 9 18 13 03 2 U8 1 U19 10 U15 4 U7 4 U30 1 U2 13 U23 12 OSCILLOSCOPE SETTINGS 1us O 1V Div 5us E 1V Div Zus O
13. 2 for proper signal Check TP 6 for proper signal Check TP 8 for proper signal Check Q2 Q3 and supportive circuit see schematic See Figure 10 in the installation section of this manual Check for proper cable installation of flat cable Check for shorts on U6 between pins 16 4 15 5 14 6 13 and 7 Also check for defec tive chips on data control line Check TP 15 for high signal If not okay see schematic Check TP 11 If not okay see schematic 24 CORVUS DEALER SERVICE SYMPTOMS FAULTS OUT continued EXCESSIVE SOFT ERRORS HARD ERRORS POSSIBLE CAUSE Phi Baud circuit defective Bus direction improper Defective Video Frequency chip Bus direction improper Tape position error Low quality damaged or worn tape VCR heads dirty Backup not good CRC chip malfunction Oscillator circuit bad Parallel Serial conversion malfunction DATA COMMAND line short Bad IC on DATAICOMMAND lines Video input circuit defective Bus direction improper Mirror not enabled No Startbit No SYNC pulse Phi Baud No STROBE signal No stop bit Defective VCR TROUBLESHOOTING PROCEDURE Check TP 7 for proper signal If not okay check appropriate input to flip flop including the soft five volt line Check TP 10 for a toggling signal during playback and a high signal during record Check TP 14 for proper signal Check to see that the proper IC is inserted at U3
14. 2V Div 2V Div 5us 1V Div 1us 1V Div 200ns 2V Div 50us 1V Div 2V Div 2V Div 50us 1V Div 50us 1V Div 2V Div 2V Div 2V Div 10us 1V Div Test Test Test Point Point Point ME M i E T in Signal Signal Signal Name Name Name Serial Serial Video In Data In Data Out Test Test Test Point Point Point E i RAV AA AAA Signal Signal TH Signal i Name Ns Name DEREN N NAA UUPVANMW TAA AMAA Ja AP YAH Test Test Test Point Point Point NE Signal Signal Signal Visync Sync Strobe 26 Atc VISIONS REV DESCRIPTION PVD DATE 2 22 e RESET Ges lA REL FOR Prod Se 2 a 05 L DI Er v D kj ajaja a IAS LR CNA 6 UE DI er AZ LU EE A ER AA SAA rr a2 ca rar III LLL ec Ji 25 12 25 2N3906 x Te illa lee 9 Reati T 11 ars 3145 ALT SEL UJZ 11 47 ONE 14 VREF Q3 Sr V 2N2222 ALT SEL Ya I 9 5 alslelslal adsleislz ulolslzlolsjalaj2 l 4115 5 14 6131 7 ei Bus DIR 31 9 Y RSTD C c 8A CBA Y A b C D E F 6 H 15158 U4 15175 U3 15138 Ull 15138 UI2
15. B Usage sr re TER er 19 4 4 Mirror Error Codes aa ded IO RA EI AAA A qa hay RR 20 CORVUS DEALER SERVICE CHAPTER 5 TROUBLESHOOTING 5 0 Scope of Chapter ai en nee ee 21 5 1 Initial Troubleshooting eda re 21 5 2 Troubleshooting Gulden ren 22 5 2 1 Computer Can t Communicate with Drive 23 5 2 2 StayS BUSY sas ua EET 23 5 2 3 TIMES QUE Susan betes 24 5 2 4 Nodmage Found 422 RD 24 5 2 5 Faults UE V ne popup Bag an 24 5 2 6 Excessive Soft Errors ac dde 25 5 2 7 Hard Errors NK Ba S ia 25 ILLUSTRATIONS Figure 1 Video Frame dua credam c rc ee 4 Figure 2 Video Format aaa 5 Figures Video Signal u uqusqa a arana ae EE a 6 Figure 4 System Block Diagram 603 cu Shs owned ER I I I aa 7 Figure 5 Control State Machine A ass seien ER a de VM god 9 Figure 6 Record Mode Aia CTS Ep 11 Figure Playback Operation ans A ARS As a tend DEC 12 Figure 8 Bottom Service Door with Mirror L Lire eene ehh hne 14 Figure 9 Video Connections ise a am PEE NU MENS Demut 15 Figure 10 Mirror Microswitches 0 oe A p ER NUES FERVOR a 15 Figure 1L Dri
16. Detection and Correction Error detection is performed with a CRC checksum routine In record the data is sent to a CRC Generator including the SYNC header After the last byte is received the CRC generator is put into the write mode and two bytes of the CRC sum are added to the data stream On playback the data stream and the CRC data bytes are input to the CRC Generator Following the second CRC byte the CRC indicator will change to indicate that the sum matches if no errors have occurred The microprocessor samples the signal and validates the buffered data for proper synchronization and content Error correction is accomplished in two separate processes First each block of data is recorded twice once in the upper half of the video frame and once in the lower half see Figure 1 Each frame is then recorded twice through software commands providing quad redundancy to enhance data recovery capabilities CORVUS DEALER SERVICE Error correction provides protection from scratches or imperfections on the video tape that may corrupt a number of blocks that are physically located in similar places on the tape There is still an excellent possibility of recovering data even if all blocks are corrupted This is accomplished by comparing the two blocks in each frame to each other If the block contains the same data no errors are assumed The blocks are compared at the beginning to find the first error and at the end of the block
17. ICE CHAPTER 3 MIRROR INSTALLATION i v W H M Tn vY A M CORVUS DEALER SERVICE CHAPTER 3 MIRROR INSTALLATION 3 0 Scope of Chapter This Chapter will describe the unpackaging and installation of your Corvus Mirror It contains step by step cabling procedures and diagrams for proper installation of both the self contained Mirror and the stand alone version The Remote option installation for the Panasonic NV8200 video cassette recorder is also described 3 1 Connecting a Mirror to the Disk The Corvus Mirror is packaged in one of two configurations self contained within the drive cabinet or as a stand alone Mirror in its own enclosure The following installation procedures apply to both single user and network systems If you received a self contained Mirror allconnections between the drive and the Mirror have already been made You need only to make the connections between the drive cabinet back panel and your video cassette recorder The VIDEO OUT from the drive should be connected to the VIDEO IN of the VCR and the VIDEO IN plug of the drive should be connected to the VIDEO OUT of the VCR 3 2 Unpackaing and Parts Checking Carefully unpack the Mirror and check for shipping damage Retain all packaging material and receipts in the event that any claims for shipping damage are filed All damage claims should be filed promptly with the transportation company Your Corvus installation package should include the follo
18. THE CORVUS SERVICE MANUAL CORVUS SYSTEMS DISCLAIMER OF ALL WARRANTIES amp LIABILITIES Corvus Systems Inc makes no warranties either expressed or implied with respect to this manual or with respect to the software described in this manual its quality performance merchantability or fitness for any particular purpose Corvus Systems Inc software is sold or licensed as is The entire risk as to its quality or performance is with the buyer and not Corvus Systems Inc its distributor or its retailer The buyer assumes the entire cost of all necessary servicing repair or correction and any incidental or consequential damages In no event will Corvus Systems Inc be liable for direct indirect incidental or consequential damages even if Corvus Systems Inc has been advised of the possibility of such damages Some states do not allow the exclusion or limitation of implied warranties or liabilities for incidental or consequential damages so the above limitation may not apply to you Every effort has been made to insure that this manual accurately documents the operation and servicing of Corvus products However due to the ongoing modification and update of the software along with future products Corvus Systems Inc cannot guarantee the accuracy of printed material after the date of publication nor can Corvus Systems Inc accept responsibility for errors or omissions NOTICE Corvus Systems Inc reserves the right to mak
19. ck pulse the last data bit is decoded from the data stream and shifted into the shift register The State Machine then sends a STROBE to indicate that the next byte of data is ready on the bus With the shifting process idle the State Machine enters a WAIT state on the next clock pulse Again this state corresponds to the stop bit time 10 CORVUS DEALER SERVICE REFERENCE VIDEO VOLTAGE IN ee ee eee CONTROL WRITE e dano kia sO LR DEVICE CONTROLLER L 3 i VIDEO STANDARD TIMING GENERATOR C PHI BAUD GENERATOR Figure 6 Record Mode 11 CORVUS DEALER SERVICE REFERENCE VIDEO VOLTAGE IN TT TT ee ne LIES RESTORE SEPAR SYNC GENERATOR CIRCUIT _ _ fr READ III l n MACHINE m READY I der i gt STROBE VIDEO STANDARD TIMING I i GENERATOR CRC SHIFT GENERATOR REGISTER PARALLEL DATA DATA PHI BAUD GENERATOR lt mmm cn l ALT SEL DEVICE BUS DIR CONTROLLER Lo lena VIDEO e OUT Figure 7 Playback Operation 12 CORVUS DEALER SERV
20. ck the data is converted back from serial to parallel form The CRC Generator monitors the data stream on both the recording and playback modes On record it generates the CRC checksum and on playback it is added to the data stream to verify the validity of the recorded data The Multiplexer is used as a switch to control the inputs to devices in either the Read or Write modes For example the SYNC signal is outputted by the MUX and switches either the SYNC generated by the Video Timing Generator when in the Write mode or the SYNC generated by the input video signal in the Read mode The R W line determines the mode The Line Control Device is a group of components that provide the appropriate signals and controls i e Preset Error Status and Data CRC Select to the Mirror interface It is controlled via the ALTISEL BUS DIR and the DATA BUS signals from the Controller CORVUS DEALER SERVICE CONTROL STATE MACHINE RECORD N0 OUTPUT START BIT HI LATCH DATA SEND STROBE ACCEPT DATA NEXT PHI BAUD CYCLE PLAYBACK N0 OUTPUT NO OUTPUT NEXT PHI BAUD CYCLE SHIFT START BIT LO DATA DATA OUT DATA CLOCK N pu CLOCK PULSE PULSE 8TH 10 START BIT 8TH BAUD CYCLE GENERATES DATA BAUD CYCLE 2 CLOCK PULSE NO YES YES N0 SEND NEXT PHI BAUD CYCLE NEXT PHI BAUD CYCLE Figure 5 Control State Machine 2 5 Error
21. ction sse s suq l vous ukun a E u py decus 8 2 5 Error Detection and Correction o abe Bak wa S a AI Swe 9 2 6 Record Operations re ee Dia A IRE 10 2 7 Playback Operations see een ASSEN eho Reda i ush anaes WEA rs 10 CHAPTER 3 MIRROR INSTALLATION 3 0 Scope rct C 13 3 1 Connecting a Mirror toa Drive ura nu a in De Cie heap D e EDO x 13 3 2 Unpackaging and Parte Inventony erkenne lese ken 13 3 3 Installation rca LIO een 13 3 3 1 Internal Mirror k Ue aaa ene iaia 13 3 3 1 1 Installing an Internal Mirror in an 11 and 20MB Drive 13 3 3 1 2 Installing an Internal Mirror in a 6MB Drive 14 3 3 2 Stand Alone Mit meer lea see 16 CHAPTER 4 MIRROR DIAGNOSTICS 4 0 SCOpe a ee INR canta US in paren RICE Acide ad 18 4 1 Mirror Diagnostics re ee Mr ple md Cx NE a El ea 18 4 2 OPTIONS G pel ete eg en ee IRA 18 4 2 1 PR WOOD Oia Re RAR 18 4 2 2 SUM Opon d Dee 19 4 2 3 TE Option susanne as Ub D aai pad dx Ue 19 4 2 4 ZERO 19 4 2 5 IMG CODDOI N AR 19 4 2 6 RES Option bis ea A A ees 19 4 2 7 VER Option are ee en 19 4 2 8 QUIT Optionas ect peat kuah prep 19 4 3 MIRDIA
22. d in the Quick Checks to ensure that a simple oversight may not be the culprit QUICK CHECKS 1 Be sure that your drive is functioning properly with your computer If your computer has problems communicating with the drive disconnect the Mirror interface and make another attempt If it works there is definitely a Mirror hardware problem because all data lines and control lines pass through the Mirror interface when it is installed 2 Using a DC Volt meter check for 5VDC at the 27 pf capacitor located next to J1 on the Mirror interface board Check from the positive side of this cap to ground It should vary no more than or 1 volt 3 Check to see that all settings on the VCR are correct Video casette recorders differ and offer various options but the following standard switches should be set accordingly Turn off any accessories not needed Input switch should be on line TVIVTR switch should be set to VTR Tracking should be set to midrange Tape speed should be set to midrange NOTE Most VCRs have detents on tracking and play speed adjustments Set these at detent 4 Verify that the installation of the video cables is correct i e VCR video out to Mirror video in and VCR video in to Mirror video out Check for corrosion at the connectors and replace if necessary 21 CORVUS DEALER SERVICE 5 One test for checking the continuity of the video connectors video cables and Mirror circuitry is to d
23. e allows for the synchronization of the sending and receiving of the data to the predefined video frame standard of the horizontal lines During the record the SYNC line is generated by the interface and the controller synchronizes the data to the video generator On playback the SYNC signal is separated from the data stream The only signal required to connect to the video recording medium are standard Video In Out signals The output is composite of the sync from the video generator and the data supplied from the controller The input is only the recorded version of the output signal CORVUS DEALER SERVICE 2 4 Component Interaction The Mirror interface components can be grouped into eight major areas Oscillator Video Standards Timing Generator Video Summing Circuit Control State Machine Shift Register CRC Generator Multiplexer Line Control Device The signal from a 14 318 MHz Crystal is divided down to provide the 3 58 MHz signal for the Video Timing Generator anda 1 1 MHz signal for the data stream transmission clock Phi Baud clock The Phi Baud clock provides clock pulses for the Control State machine providing data shifting information The 5 bytes per horizontal line format can be altered to accommodate other line byte requirements see Figure 5 The Video Standards Timing Generator is used during record to provide for the standard television format that is then modulated with data The SYNC output provides the external
24. e changes in the product described in this manual at any time without notice Revised manuals and update sheets will be published as needed and may be purchased by writing to CORVUS Corvus Systems Inc 2100 Corvus Drive San Jose California 95124 408 559 7000 Telex 278976 This manual is copywrited and contains proprietary information All rights reserved This document may not in whole or in part be copied photocopied reproduced translated or reduced to any electronic medium or machine readable form without prior consent in writing from Corvus Systems Inc Copyright 1984 by Corvus Systems Inc All rights reserved Mirror patent pending The Corvus Concept Transporter Corvus OMNINET Corvus Logicalc Time Travel Editing EdWord Constellation Corvus Corvus Systems Personal Workstation Tap Box Passive Tap Box Active Junction Box Omninet Unit are trademarks of Corvus Systems Inc CP M is a registered trademark of Digital Research Inc Apple Apple II and Apple II Plus are registered trademarks of Apple Computers Inc TRS 80 and Radio Shack are registered trademarks of Tandy Corporation SuperBrain is a registered trademark of Intertec Data Systems Inc DEC LSI 11 RL01 and RL02 are registered trademarks of Digital Equipment Corporation UCSD PASCAL is a trademark of the Regents of the University of California IBM is a registered trademark of IBM Corporation
25. hese diskettes are designed to exercise the Mirror interface and can be used in conjunction with the troubleshooting procedures outlined in chapter five 4 1 Mirror Diagnostics The Mirror diagnostic program MIRDIAG provides a comprehensive test for the Mirror VCR interface The MIRDIAG program is a combination of Pascal and machine code programs which allow the technician to perform extensive tests of the Mirror interface board for short or extended time periods 4 2 Options MIRDIAG has a series of options which you can select to exercise the functions of the program 4 2 1 PRM Option The PRM parameter option allows you to set the test parameters The following are a list of parameters and descriptions which can be set by the PRM option Loop Test VCR Test This option allows you to select tests with a VCR or optionally use test drive with known good components to test a suspect drive and Mirror The default value will be VCR for the VCR test Slot Number This option allows you to select the computer slot which is connected to the drive under test If VCR test has been selected a single slot will be specified The default slot for the VCR test will be slot 2 If loop test has been selected then a sending slot and a receiving slot will be specified The default value for the loop test will sent slot 1 and receive slot 2 Automatic VCR Control With this option you will be able to specify whether automatic VCR control is t
26. his produces a black signal if it is a 0 or a white signal if it is a 1 After the next Phi baud clock pulse a Data Clock pulse is sent to the shift register which in turn clocks the next data bit to the serial output This bit is then added to the video output signal and this process continues until all the bits are shifted out in a total of eight clock pulses When the last data bit has been transferred the interface becomes idle for 1 clock pulse and the output of the video summer is 0 This state corresponds to the Stopbit time 2 7 Playback Operation The playback operation of the Mirror interface is very similar to the record mode as you will see except that it is the inverse of that operation Beginning with the interface in an idle state SYNC pulses are separated from the video input signal and are transferred to the external interface controller With the R W line in the Read mode serial data out of the comparator is input to the shift register the control state machine and the CRC generator checker see Figure 7 A high level out of the comparator is interpreted as a Startbit This triggers the Control State Machine to start inputting data Following a Phi baud clock pulse a data clock pulse is sent to the shift register from the Control State Machine which clocks the next data bit to the serial input This continues for 8 clock pulses until all the bits are shifted into the shift register Following the 8th data clo
27. ideo signal Serial data not being generated ALTISEL signal is not selecting properly for data signals and command signals Not receiving data TROUBLESHOOTING PROCEDURE STAND ALONE MIRROR Check cable at the rear of drive to ensure proper connection Remove top of Mirror and check for proper cable installation See section 3 3 2 in this manual Check for 5VDC as described in Quick Check 2 6MB INTERNAL MIRROR Check the microswitch setting at the rear bezel see Figure 10 for proper setting Remove top of drive and check to see that the Mirror board is seated well into the backplane Also check flat ribbon connector at the rear bezel of the drive 11 20MB DRIVE Open service door on bottom of drive and check all connections see section 3 1 1 1 in this manual Also check flat ribbon connector at the rear bezel of the drive Check TP 4 It should be constantly high SVDC If okay check U3 for proper operation Check to see that the proper IC is inserted at U30 2622 for NTSC format and 2621 for PAL SECAM format If okay check Q1 see schematic Check the microswitch setting at the rear bezel see Figure 10 for proper setting Check Mirror board for broken wires on video in line Check TP 2 for correct signal If not okay see schematic Check TP 13 for low signal during data transfer Check cable connections Quick Check 3 Check TP 1 for proper signal V M
28. ill also have Mirror backup capability CORVUS DEALER SERVICE 1 3 Video Recorder Compatibilities Brand names and model numbers of video recording machines that have actually been used with the Mirror by Corvus or Corvus customers successfully are listed below We recommend that customers interested in using a VCR not listed below test the recorder with a Mirror before the purchase is made Grundig RCA VCR 4000 VDP 150 180 an VCT 201 VDT 350 Magnavox VDT 501 8315 VET VFT 450 8325 VET 190 8335 Sylvania tl VC 2210 E pared Technicolor 212 Maximum National recording time NV 7000 30 minutes Panasonic Quasar PV 1200 VH 5011 PV 1210 VH 5015 PV 1270 VH 5210 PV 1370 VH 5310 PV 1470 VH 5610 PV 1770 VHS 1000 Zenith VHS 1500 VL 9700 Beta NV 1330 NV 3700 NV 8200 NV 8310 NV 8320 NV 8410 A remote option has been designed to allow complete unattended operation using the Panasonic NV 8200 Various recorders on the market are equipped with a color enhancement feature This feature confuses the Mirror by trying to superimpose color onto the backup image Use of recorders with this feature should be avoided unless the customer has the expertise to disable the color enhancement circuitry in the recorder while using the Mirror L4 Video Tape Compatibility In order to obtain the lowest number of errors a quality video tape should be used Defective or worn tape can also cause problems when tryi
29. ng to backup For that reason we strongly reemphasize the use of good quality tape for storage of your backup data The Maxell Epitaxial has been selected for our inhouse use While performing backup you should use the SP record mode with VHS recorders and Beta 1 mode when available with BETA recorders The actual tape speeds for these modes and for the Technicolor 212 recorder are as follows VHS SP Mode 1 31 IPS BETA Beta 1 1 57 IPS Technicolor 212 1 26 IPS CORVUS DEALER SERVICE Although backups from several different days can be stored on a single tape we recommend backing up each day with a different cassette in order to protect against destruction of your data Magnetic or physical damage accidental erasing or tape misplacement will not be a catastrophic loss if you have recorded each days image on individual tapes The ratio of data storage to cassette lengths is listed below 30 minute tapes Ter uy wy A eae ROLE 18 MB 60 minute tape ea es RO WES 36 MB OO minute tape correa Lar Save ee an 55 MB 120 minute tape na as 73 MB CORVUS DEALER SERVICE CHAPTER 2 FUNCTIONAL DESCRIPTION CORVUS DEALER SERVICE CHAPTER 2 FUNCTIONAL DESCRIPTION 2 0 Scope of Chapter In this chapter we will be describing the various components and devices in the Corvus Mirror interface board Various areas covered will include Mirror O
30. o Ac Cable Figure 11 Drive Rear Bezel 16 CORVUS DEALER SERVICE Attach the other end of this cable to the drive connector on the Mirror interface board see Figure 12 TO MUTLI Figure 12 Stand Alone Mirror 4 Connect the cable from the interface card Multiplexer or Disk server to the remaining 34 pin connector on the Mirror interface board as shown in figure below 5 Ifyou have a 6MB drive set the switches on the rear panel of your drive making sure that the switches are fully depressed see Figure 10 6 If you have ordered the Remote option install the Remote Cable to the 20 pin male connector J3 on the interface board see Figure 12 7 When you are sure that all connections at the interface board are correct according to these instructions reassemble the interface box and connect the ac cable 8 To connect the phono plug cable whether for a self contained Mirror or a Stand Alone Mirror be sure that the VIDEO OUT of the Mirror goes to the VIDEO IN of the VCR and the VIDEO IN of the Mirror comes from the VIDEO OUT of the VCR Reminder THE REMOTE OPTION ONLY WORKS WITH A PANASONIC NV8200 VIDEO CASSETTE RECORDER CORVUS DEALER SERVICE CHAPTER 4 MIRROR DIAGNOSTICS CORVUS DEALER SERVICE CHAPTER 4 MIRROR DIAGNOSTICS 4 0 Scope of Chapter The intention of this chapter is to familiarize the reader with the Mirror diagnostic that are contained in the Dealer Service Diagnostic diskettes T
31. o be used during testing This option will only function with the Panasonic NV8200 VCR The VCR must have the remote cable connected in order for this to operate correctly The default value for VCR control is Yes Block Pass The number of blocks per pass can be set during backup and restore operations by selecting this option Default is 512 blocks Starting Address The starting address can be specified for backup operations by using this option Restore Address This option allows you to specify which address you wish to restore data to during the restore operation The default value for Restore Address is 512 This must be greater than the last address backed up to ensure that the compare function operates properly Bidirectional Transfers If you wish the Mirror transfers to be bidirectional during loop test select this option If you select Yes the program will alternate backups and restores or verifies on each of the two slots specified The default value is N Restore Verify This option allows you to select restore or verify passes after the backup pass For non destructive testing select the verify option For more comprehensive testing use the restore option which will destroy data on the disk The default value for Restore Verify is Verify Test Image Test Image allows you to specify if a test image is to be written to the disk prior to backup This option is destructive to data on the test disk The
32. o the LOOP BACK test Simply connect the video out of the Mirror to the video in of the Mirror essentially looping the signal back in Run an Identify operation and after 2 minutes and 35 seconds the Mirror should time out 6 Ensure that tape positioning is correct Improper positioning can cause the image header to be missed which will hang the operation 7 A quick way to check if data is being transmitted from the drive during a backup or from the VCR during a restore is to connect the video out cable to the monitor The photograph below illustrates data as it should be seen on the monitor Figure 13 Monitor with Data Displayed 5 2 Troubleshooting Guide The following guide has been based on symptoms that may be encountered if a Mirror malfunction occurs during an operation It is designed to point the qualified service technician toward a possible cause of the problem The initial indications are described as are the probable causes and the Test Points A troubleshooting guide has been included to facilitate servicing Photographs are provided of test points and of signals that should be seen at those test points 22 CORVUS DEALER SERVICE SYMPTOMS Drive does not communicate with computer STAYS BUSY TIMES OUT TROUBLESHOOTING GUIDE POSSIBLE CAUSE Loose connection No 5VDC Switch Settings Loose connection Soft Reset continually on Incorrect video signal Switch settings 6MB No v
33. r is packaged in itsown box and must be connected to the drive with flat cable For stand alone Mirrors the Mirror is connected between the Corvus disk and the personality card that interfaces your computer to your Corvus hard disk On network systems it is connected between your Corvus Disk and the Multiplexer or Disk Server You must detach the cable that connects the drive to the personality card Multiplexer or Disk Server from the drive cabinet rear panel and attach the free end of this cable to the Mirror interface board The flat cable supplied with the Mirror is then connected to the back panel of the drive cabinet and the Mirror interface board Finally the Mirror is connected to the VCR with the supplied phone plug cable Incorrect cable installation will not allow proper operation of your Mirror 1 To begin remove the cover from the stand alone Mirror enclosure 2 Detach the flat cable from the connector labeled PROCESSOR on the back panel of the drive cabinet The end of this cable should be attached to the disk interface card or a multiplexer or disk server if connected to a network 3 Attach the cable that came with the Mirror to the back panel of the drive cabinet to the connector labeled PROCESSOR Connects to Connects Connects Air Flow Slots Video Remote to Interface to Add on Control Card Drive if any PROCESSOR Connects to Video Recorder Mirror Dip Switches Power Switch Connects t
34. r this option you can specify the location where the data will be restored to The block pass parameter must match the size of the image recorded 4 2 7 VER Option The VER option allows you to verify a Mirror image There are no parameters that affect this option 4 2 8 QUIT Option The QUIT option allows you to leave the Mirror diagnostic and return to the main diagnostic menu 4 3 0 MIRDIAG Usage The typical use for the Mirror program is to test the Mirror for functionality If you have a Panasonic NV8200 with the remote cable you can use the test as is without changing any parameters If you do not have a remote cable or have a different VCR you can use the parameter option to change the automatic VCR control option Use the default values for all other parameters After the parameters are set use the TST option to start the test procedures We recommend that you run 2 to 4 passes for each Mirror On a 512 block test you should get approximately 10 soft errors per pass If you perform 2 tests the total should be approximately 20 remember that all tests are cumulative until you zero the counters Most other types of recorders will yield a higher soft error rate Under no circumstances should there be any hard errors If hard errors do occur there is most likely a problem in the Mirror card Under no circumstances should you encounter CRC errors or Disk Errors on backup If you encounter these errors run the drive diagnostics to check out
35. rface in the event that you should encounter difficulties in operation While some of the problems you may experience might seem to be hardware malfunctions they may be created by other causes To facilitate the isolation of any problem we have organized our troubleshooting approach to reflect the indications that you would see during the Mirror operation These indications are organized into the following categories STAYS BUSY The busy light remains lit TIMES OUT Returns to the ready state very quickly FAULTS OUT Goes to fault status and remains in that state ERRORS Reports hard errors or an excessive amount of recovered soft errors NO IMAGE FOUND Image header not found during a Restore Verify or Identify Many of these indications may occur due to operational and installation mistakes video equipment failure or hardware failures other than the Mirror interface In this chapter we will be addressing the lower level complications as well as some of the more complex problems that would require digital troubleshooting skills We have identified selected test points in our troubleshooting guide and have attached schematics in the appendix to offer low level troubleshooting capabilities to qualified service technicians 5 1 Initial Troubleshooting The initial approach to troubleshooting any system is to eliminate the most obvious causes which may be creating the problem We recornmend the following procedures that are outline
36. signal for recording on a video cassette recorder The Corvus Hard disk uses the Z80 microprocessor resident on the controller card to provides an intelligent interface to the host computer The host computer specifies one of three operations for the mirror Write Read or Verify In the Write operation a portion of or an entire drive can be transferred to the cassette tape The Read operation transfers the data from the tape to the disk and the Verify operation uses proven error detection procedures to ensure the readability of the data This function provides a quick self test to ensure the backup system is functioning correctly The Mirror contains Cylical Redundancy Check CRC detection hardware using the standard CRC polynomial Each block of 532 bytes consists of a header containing file information 512 blocks of data and two bytes of information Software is provided for each host computer and operating system to back up an entire disk or a selected portion of a disk 1 2 Computer Compatibilities The Corvus Mirror will interface with a wide variety of host computers The following list represents our present interface product line to which the Mirror is capable of backing up Apple II Superbrain Apple TRS 80 Mod I Atari 800 TRS 80 Mod II Commodore TRS 80 Mod III Hewlitt Packard Zenith IBM Personal Computer DEC Robin NEC 5 100 Computers Xerox 820 Sony Future microcomputers interfacing with Corvus mass storage systems w
37. t side of the board is facing out and that the board is well seated into the backplane and into the standoffs 3 Replace the cover of the drive and reinstall the hardware 4 There are a series of four microswitches on the rear of the drive 14 x CORVUS DEALER SERVICE Connects to Video Remote Control VIDEO Connects NCR REMOTE to Video Recorder ovr Figure 9 Video Connections 5 MB SWITCH SETTINGS The dot indicates that the switch should be pressed down on that side DRIVES WITH DRIVES WITH DRIVES WITH MIRROR OR EXTERNAL MIRROR PAL SECAM MIRROR NTSC MIRROR Hz Fer imecp 4642 GO fecho LE21 56 He CHp Figure 10 Mirror Micro Switches 15 CORVUS DEALER SERVICE When the internal Mirror is installed all switches should be in the open position that is allswitches are pushed in at the bottom see Figure 10 Be sure that the switches are completely pushed in as these switches have a tendency torock back to their original position 5 If the drive is of PALISECAM format European switch one will remain in the closed position see Figure 10 6 Installthe video cable from the drive to the VCR making sure that the video out from the drive is connected to the video in of the VCR and the video in of the drive is connected to the video out of the VCR 3 3 2 Stand Alone Mirror If you have ordered a Mirror to compliment an already existing Corvus drive the Mirro
38. the under side of the drive Open the trap door see Figure 8 2 Mount the internal Mirror board onto the trap door with the hardware provided 13 CORVUS DEALER SERVICE Disconnect the drive flat cable from the male end of the processor flat cable flat cable with double connectors and install the 100 mil drive cable to the grey male connector on the Mirror board 4 Install the female end of the processor cable flat cable with double connectors onto the black male 200 mil connector on the Mirror board 5 Locate the white connector with four wires on the Mirror board and connect it to the matching connector going to the rear bezel 6 Check to ensure that all connections are secure and close the trap door making sure that the cabling is not pinched 7 Replace the hardware securing the trap door Figure 8 Bottom Service Door 8 Connect the video cable into the VIDEO OUT of the drive to the VIDEO IN of the VCR and the VIDEO IN from the drive to the VIDEO OUT of the VCR see Figure 9 9 If you are using a Panasonic NV8200 with the remote option install the remote cable to the connector VCR Remote on the rear bezel see Figure 9 3 3 1 2 Installing an Internal Mirror ina 6MB Drive 1 Remove the allen head screws securing the top cover of the drive and remove the top 2 Install the Mirror interface board into the vacant slot of the backplane which is attached to the top cover of the drive Be sure that the componen
39. time Data bits are individually shifted in the shift register until eight bits have passed and the stop bit is recognized The stop bit initiates the data handshake routine with the I O port which then latches the data until it is read by the microprocessor 2 2 Video Format The DATAISYNC information header and error checking make up a data block The SYNC header is provided to synchronize the reading of data to the start of that data The SYNC hunt looks for the TYPE FILE ID and INVERSE FILE ID to indicate the start of the block i e leader data or trailer block To facilitate the tape positioning during file searches each block contains RELATIVE BLOCK number which relates to the first block and the number blocks in the file For example the first block is relative block number zero the second block is relative block number one etc SYNC HEADER 107 LINES CRC LINE BLOCK Figure 2 Video Format CORVUS DEALER SERVICE Two bytes are transmitted at the start of the last line that represents the CRC SUM of the block and they facilitate error detection on playback The termination byte TERM is transmitted at the end of the last line Its purpose is to reset the CRC generation circuitry on the mirror interface so that good CRC is only possible for a two byte time following the reception of the CRC bytes Since good CRC can only be sampled during this brief window the hardware will be able to detect loss of
40. ve Rear Bezel iii nee a S aos pa age 16 Eigur 12 Stand Alone Minor zx ev bx he acca than RR Fa e AU See IF Br eges e ere doo E A Oc ite Qd 17 Figure 13 Monitor with Data Displayed uio a 22 Figure 14 Mirror Board with Scope Signals a 26 SCHEMATIC DRAWINGS 10120 MB Mirror Schematic a a e Pea oe 27 5 MB Mirror Schematic en Nase 28 CORVUS DEALER SERVICE CHAPTER 1 MIRROR OVERVIEW CORVUS DEALER SERVICE CHAPTER 1 MIRROR OVERVIEW 1 0 Scope of Chapter This chapter will familiarize you with the capabilities and compatiblities of the Corvus Mirror You will also be familiarized with some of the terms that you will need to understand the general function of the Mirror 11 Introduction to the Corvus Mirror The Corvus Mirror provides an efficient and inexpensive backup for the Corvus family of Winchester disk drives It also provides archival storate for large data base systems on low cost removable video cassette tape with the ability to store more than 70 Megabytes of data The Mirror is fully compatible with the standard NTSC video format used in the United States and also can be purchased in a PAL SECAM version which is the standard video format used in European countries A Z80 microprocessor is used as a controller with the Mirror as a formatting interface to convert data from a digital signal to a video
41. verview Video Format External Signal Component Groups Error Detection and Correction Record Operation and Playback Operation We will communicate the technical concept of the Mirror devices and their functional interactions 2 1 Mirror Technical Overview The Mirror interface utilizes the Z80 microprocessor and 3K of RAM in the disk controller and is controlled through an 8 bit data bus and 7 control lines The combination of the intelligent Disk Controller and the Mirror data formatting interface converts the data from a digital signal to the proper format needed by the video cassette recorder for storage The converted digital signal is anagolous to a black and white picture with 2 identical frames recorded on it Each frame is made up of 240 lines with certain lines reserved for vertical retrace and data is stored on 2 blocks of each frame Figure 1 depicts the make up of a video frame START OF VERTICLE RETRACE VISIBLE PORTION BLOCK 1 INTER BLOCK BUFFER BLOCK 2 END OF HEAD RE SYNC BUFFER VISIBLE PORTION ONE VIDEO FIELD Figure L Video Frame CORVUS DEALER SERVICE There are also three buffer fields that are part of each video frame The first occurs during the vertical retrace signal and the first few lines of the visible portion The purpose of this is to maintain a compatibility with future recording formats that may generate their own information during the vertical retrace blank time Interblock
42. wing items 1 A Mirror if you have ordered a stand alone Mirror it is packaged in a white Corvus Mirror enclosure 2 Corvus Mirror utilities diskette Only if you have ordered a separately packaged Mirror for Disk System or if your Corvus interface PROM is less than version 3 0 Otherwise Mirror utilities are on the Corvus Disk Drive utilities diskette that comes with your drive 3 Dual phone plug cable for the VCR 4 A flat ribbon cable with a 1 Mil connector at one end and double connectors 1 Mil and 2 Mil at the other 5 Remote option cable if you ordered the remote option with your Mirror 6 Warranty Card 3 3 Installation Be sure that the power to both the computer and to the Corvus drive is off anytime you install or remove any circuit cards or cables Failure to do so may cause permanent hardware damage 3 3 0 Internal Mirror If you ordered a self contained Mirror with your drive the Mirror printed circuit board is located inside the drive cabinet You only need to connect the video cable to the back panel of the drive cabinet NOTE If you are using 6MB drive verify that the microswitches on the rear bezel are set correctly see Figure 10 3 3 1 Installaing an Internal Mirror on a 11MB or 20MB Drive If you are adding an internal Mirror to your drive follow the steps outlined below carefully for installation 1 Turn the drive on it s side and remove the two allen head screws securing the trap door on
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