Macintosh Plus
Contents
1. Service Source Macintosh Plus gt Service Source Basics Macintosh Plus m Overview 1 Overview This manual contains complete repair procedures for the Macintosh Plus shown at left Figure Macintosh Plus m Service Source Specifications Macintosh Plus n o Specifications Introduction 1 Introduction Specifications information for this product can be found in this chapter and also in the Spec Database which you can access in one of three ways Launch it directly by double clicking the Apple Spec Database runtime alias at the top level of the Main Service Source CD Select Apple Spec Database from the Service Source drop down main menu Click the Acrobat toolbar icon for the database which is near the right end of the toolbar with the letters SP m Processor 2 CPU Processor Motorola 68000 microprocessor 7 83 MHz 32 bit internal data bus m o Specifications Memory 3 Memory RAM 1 MB expandable to 4 MB 150 ns or faster SIMMs ROM 128K PRAM CMOS custom chip with 4 5 V user replaceable battery backup includes 256 bytes of memory remembers system parameters even with the machine switched off m o Specifications Disk Storage 4 Disk Storage Floppy Drive Internal double sided drive uses 3 5 in hard case floppy disks either double sided 800K capacity or single sided2. nu Service Source Take Apart Macintosh Plus n Cover 1 Battery Compartment Cover Switch Reset Interrupt Cover No preliminary steps are required before you begin this procedure A warning This product contains high voltage and a high vacuum picture tube To prevent serious injury review CRT Safety in Bulletins Safety 1 Remove the battery compartment cover 2 Remove the reset interrupt switch if present ui Cover 2 Using a Torx screw driver remove the case screws including the one in the battery compartment Using the pull apart tool gently pry off the cover A warning The edges of the metal chassis may be sharp When moving the computer with the cover off be sure to handle the chassis carefully m Power Sweep Board 3 Discharge ime Tool Power Sweep Board Before you begin e Remove the cover e Discharge the CRT e Remove the anode cap A Warning This product contains high voltage and a high vacuum picture tube To prevent serious injury review CRT Safety in Bulletins Safety A Warning Never use a grounding wriststrap until after discharging the CRT ui Power Sweep Board 4 1 Disconnect the following cable connectors from the power sweep board Logic Board e Yoke cable Cable e Logic board cable Neck Cable e Neck cable Yoke Cable 2 Remove the screw and lockwasher tha
3. With one hand grasp the plastic spokes of the yoke collar and rotate the yoke collar until the top and bottom edges of the picture are parallel with the top and bottom of the bezel ip Yoke 11 Yoke Collar Yoke Clamp Screw Switch off and unplug the computer Discharge the CRT Hold the plastic collar in position and slowly tighten the yoke clamp screw so that the collar cannot slip Do not overtighten the screw Replace the cover and switch on the computer Make sure the top and bottom edges of the picture are parallel with the top and bottom of the bezel lt p Yoke 12 e A J AIW e ENS eee Centering Rings Centering Ring Adjustment Note If glue holds the yoke collar in place use an art knife to cut through the glue To center the picture hold the front centering ring steady and move the rear ring Then hold the rear centering ring steady and move the front ring mn Video 13 d Power Sweep Video You must perform the video adjustments whenever the CRT or the power sweep board is replaced Before you begin remove the cover A Warning This product contains high voltage and a high vacuum picture tube To prevent serious injury review CRT Safety in Bulletins Safety ui Video 14 A warning Because you must make video adjustments from the rear of the compu ter use a mirror to view the computer scr
4. 400K capacity m o Specifications I O Interfaces 5 Floppy Drive SCSI Mouse Keyboard Serial I O Interfaces External drive port DB 19 connector One SCSI parallel port DB 25 connector Mouse port DE 9 connector Synchronous serial keyboard bus RJ 11 connector Two RS 422 serial ports mini DIN 8 connectors m o Specifications I O Devices 6 Keyboard Mouse I O Devices 78 keys including numeric keypad and cursor keys RJ 11 connector Mechanical tracking optical shaft encoding at 3 54 pulses per mm 90 pulses per in of travel DE 9 connector m o Specifications Sound and Video 7 Sound and Video Sound Generator Four voice sound with 8 bit digital analog conversion using 22 kHz sampling rate Video Display 9 in diagonal screen 512 by 342 pixel bit mapped display m o Specifications Electrical 8 Line Voltage Freguency Maximum Power Electrical 105 125 VAC 50 60 Hz 60 W m o Specifications Physical 9 Physical Dimensions Height 13 6 in 34 5 cm Width 9 6 in 24 4 cm Depth 10 9 in 27 6 cm Weight 16 Ib 8 oz 7 5 kg m Service Source Troubleshooting Macintosh Plus nu o Troubleshooting General 1 General The Symptom Charts included in this chapter will help you diagnose specific symptoms related to your product Because cures are listed on the charts in the or
5. 5235 Platinum Ber RFI Shroud 805 5047 435 5002
6. ct the orange test lead and pull the insulated hood over the plug ili Voltage 6 9 Connect the red test cable lead to the voltage input terminal on the voltmeter 10 Switch on the computer 11 Adjust the voltage regulator on the power Voltage sweep board to between 1 W Regulator 4 85 and 5 15 volts ili Voltage 7 Voltage ii Regulator 12 Switch off power 13 Disconnect the red test lead and pull the insulated hood over the plug 14 Repeat the tests to verify that both voltages are within the specified tolerances Note If the power sweep board will not adjust so that both voltages fall within tolerance replace the board m Yoke 8 Yoke If you replace the CRT you may need to adjust the yoke Before you begin e Remove the cover e Discharge the CRT A Warning This product contains high voltage and a high vacuum picture tube To prevent serious injury review CRT Safety in Bulletins Safety quip Yoke 9 A Warning Because you must make yoke adjustments from the rear of the computer use a mirror to view the computer screen Do not reach around the computer to adjust the controls quip Yoke 10 TA ei Yoke Collar Tilt Adjustment Note If glue holds the yoke collar in place use an art knife to cut through the glue 1 N Loosen the yoke clamp screw two or three turns Switch on the computer
7. der of most likely solution try the first cure first Verify whether or not the product continues to exhibit the symptom If the symptom persists try the next cure Note If you have replaced a module reinstall the original module before you proceed to the next cure If you are not sure what the problem is or if the Symptom Charts do not resolve the problem refer to the Flowchart for the product family For additional assistance contact Apple Technical Support nu o Troubleshooting Symptom Charts Video 2 No video but audio tone is present and drive operates Screen is bright and audio is present but no video information Is present Symptom Charts Video 1 Turn contrast control fully clockwise 2 Check video cable connections 3 Replace power supply board 4 Replace neck cable 5 Replace logic board Retain customer s SIMMs Replace power supply board 2 Replace logic board Retain customer s SIMMs nu o Troubleshooting Symptom Charts Drives 3 Drives Disk ejects display 1 Replace bad disk shows disk icon with 2 Replace floppy drive cable blinking X 3 Replace floppy drive 4 Replace logic board Retain customer s SIMMs Unable to insert disk 1 Insert paper clip into small hole beside drive slot or switch all the way off system power and hold mouse button down while switching system power back on to complete eject cycle Then insert disk with metal slot forward and write
8. een Do not reach around the computer to adjust the controls Switch on the computer quip Video 15 Brightness Control Ao Bemal E Contrast Control Brightness and Contrast 1 Turn the external contrast control fully clockwise Turn the brightness control fully counter clockwise so that white lines are visible Turn the brightness control clockwise until the white lines just disappear Turn the external con trast control 1 8 of a turn counterclockwise ui Video 16 i Width Control Height Control Size Adjustment Using the alignment tool adjust the width control until the raster is 7 inches 177 8 mm wide Using the alignment tool adjust the height control until the raster is 4 7 inches 119 4 mm high ili Video 17 Focus Adjustment 1 Turn the focus control clockwise to its limit 2 Turn the focus control counterclockwise 1 8 of a turn m Service Source Exploded View Macintosh Plus m Exploded View 1 Exploded View lt Internal Drive CRT and Yoke Shield Assembly 805 0217 800K 076 0103 CRT Socket 800K Cable Floppy Drive Front 590 0160 661 0345 Bezel 810 0379 810 0385 Internal Drive Cable 590 0437 Platinum Insulator Shield 725 0011 661 0462 110V 661 76214 220V Chassis 805 0766 462 3100 Logic Board 661 0525 Rear Housing 630 5211 630
9. ge the SIMMs especially the larger DIP SIMMs that may be installed on the board Pull back on the top of the logic board and carefully slide out the logic board quip Logic Board 10 3 Note If your replace ment board is Rev D part number 820 XXXX D or higher you should install a ground clip Do not use the ground clip with any logic board lower than Rev D Caution Contact between the ground clip and pins or solder points on the underside of the logic board could cause a short resulting in erratic keyboard behavior Make sure the ili Logic Board 11 clip does not touch any solder points Install the ground clip to the inner plastic lip on the bottom front bezel Replacement Note Remove the SIMMs from the defective logic board and install them on the replacement logic board Replacement Note When exchanging the 512K logic board you must swap ROMs to the new logic board quip Logic Board 12 Replacement Note After replacing all parts except the cover perform the voltage adjustment proced ures See Voltage in Adjustments mn CRT 13 CRT Before you begin e Remove the cover e Discharge the CRT e Remove the power sweep board A Warning This product contains high voltage and a high vacuum picture tube To prevent serious injury review CRT Safety in Bulletins Safety A warning Never use a grounding wriststrap un
10. gic board Retain customer s SIMMs produces no response No response to any 1 Replace keyboard cable key on keyboard 2 Replace keyboard 3 Replace logic board Retain customer s SIMMs No response from a 1 Replace keyswitch particular key 2 Replace keyboard 3 Replace logic board Retain customer s SIMMs ui Troubleshooting Symptom Charts Peripherals Continued 7 Peripherals Continued Known good 1 Make sure that Chooser and Control Panel are set correctly ImageWriter or 2 Check that system software version is compatible Replace ImageWriter Il does software with known good not print 3 Reset PRAM 4 Replace interface cable 5 Replace logic board Retain customer s SIMMs Known good 1 Make sure that Chooser and Control Panel are set correctly LaserWriter does not 2 Check that system software version is compatible Replace print software with known good 3 Reset PRAM nu o Troubleshooting When turned on the Macintosh Plus continuously beeps and tries to power up Clicking or chirping sound Symptom Charts Miscellaneous 8 Miscellaneous 1 Perform voltage adjustment Refer to Adjustments 2 Disconnect internal disk drive If this eliminates problem replace drive 3 Replace logic board Retain customer s SIMMs 4 Replace power supply board logic board and internal drive then turn on Macintosh Note Replacing only power supply board may damage new power supply board 1 Connect log
11. grade Install two 1 MB SIMMs in Bank A and two 1 MB SIMMs in Bank B m Service Source Adjustments Macintosh Plus n Voltage 1 Power Sweep Board A External Drive Port Voltage You must verify voltages after you replace the logic board or the power sweep board Before you begin remove the cover A Warning This product contains high voltage and a high vacuum picture tube To prevent serious injury review CRT Safety in Bulletins Safety lt p Voltage 2 A Warning Because you must make voltage adjustments from the rear of the compu ter use a mirror to view the computer screen Do not reach around the computer to adjust the controls quip Voltage 3 Be xu e 7 External Drive Port Set the voltmeter to 20 volts Connect the Macintosh voltage test cable Apple part number 077 0135 to the external drive port Caution Shorting the test cable plugs to each other can damage the computer Pull the hoods over the plugs Connect the black voltmeter test lead between the voltmeter ground terminal and the computer chassis ili Voltage 4 4 Connect the orange test cable lead to the voltage input terminal on the voltmeter quip Voltage 5 Voltage ii Regulator Switch on the computer Adjust the voltage regulator on the power sweep board to between 11 90 and 12 75 volts Switch off power Disconne
12. ic board cable 2 Perform voltage adjustment Refer to Adjustments 3 Replace power supply board 4 Replace logic board Retain customer s SIMMs ui o Troubleshooting Smoke odor issues from the Macintosh Plus No video no audio tone and no drive operation Symptom Charts Miscellaneous Continued 9 Miscellaneous Continued Replace power supply board Connect power cord Turn power on Replace power cord Check fuse Replace power supply board Replace logic board Retain customer s SIMMs O U A W N quip o Troubleshooting Symptom Charts Miscellaneous Continued 10 Miscellaneous Continued MacTest displays Replace Macintosh Plus logic board Retain customer s SIMMs 128K 512K when 1 MB Macintosh Plus is tested When developer s Remove switch and file it down about 1 16 inch switch is installed Macintosh Plus sometimes resets intermittently quip Troubleshooting Symptom Charts Miscellaneous Continued 11 Miscellaneous Continued Macintosh Plus hangs 1 If logic board has ROMs 342 0341 A or B ROM HI and 342 on startup 0342 A ROM LO and a peripheral device is connected to SCSI port peripheral device must be turned on before powering on Macintosh Plus Macintosh Plus boots 1 Replace keyboard but keyboard behaves 2 Check that logic board grounding clip is not touching solder erratically points beneath logic board 3 Replace logic board Retain customer s SIMMs
13. protect tab on bottom 2 Replace floppy drive ui o Troubleshooting Symptom Charts Drives Continued 4 Does not read disks on internal drive Does not read disks on external drive Drives Continued Replace bad disk Replace floppy drive cable Replace Mylar RFI shield Replace floppy drive Verify ROMs on the logic board Replace logic board Retain customer s SIMMs O U A W N Replace bad disk Replace floppy drive cable Replace Mylar RFI shield Replace external drive Verify ROMs on the logic board Replace logic board Retain customer s SIMMs O U A W N quip Troubleshooting Symptom Charts Drives Continued 5 Drives Continued Audio tone sounds at 1 Replace floppy drive cable power on video is 2 Replace floppy drive present but drive 3 Replace logic board Retain customer s SIMMs does not operate Drive runs 1 Replace bad disk continuously 2 Replace floppy drive cable 3 Replace floppy drive 4 Replace logic board Retain customer s SIMMs 400K drive does not 1 If logic board has Rev A ROMs and drive stepper motor is boot serial number F518 or higher upgrade to Rev B ROMs 2 Replace floppy drive nu o Troubleshooting Symptom Charts Peripherals 6 Peripherals Cursor does not move 1 Connect mouse 2 Clean mouse 3 Replace mouse 4 Replace logic board Retain customer s SIMMs Cursor moves but Replace mouse clicking mouse 2 Replace lo
14. t hold the ground wire to the chassis LEN Screw amp Lockwasher quip Power Sweep Board 5 3 Note You may need to remove the insulating paper from the power sweep board to access the mounting screws Remove the three mounting screws and washers and lift the power sweep board from the chassis Replacement Note After replacing all parts except the cover perform the voltage and video adjust ment procedures See Voltage and Video in Adjustments lii Power Sweep Board 6 Replacement Note When sending Apple a defective power sweep board be sure to include the cable that connects to the logic board Make sure the contrast control knob and battery have been removed from the defective board and reinstalled onto the exchange board mn Logic Board 7 Logic Board Before you begin e Remove the cover e Discharge the CRT A warning This product contains high voltage and a high vacuum picture tube To prevent serious injury review CRT Safety in Bulletins Safety A Warning Never use a grounding wriststrap until after discharging the CRT Logic Board lt p Logic Board 8 1 Disconnect the following cable connectors from the logic board e Floppy drive cable e Logic board cable Logic Board Cable Saa Floppy Drive Cable ili Logic Board 9 Caution When removing the logic board be careful not to dama
15. til after discharging the CRT quip CRT 14 A warning Handle the CRT by its sides only Do not grasp the neck on the CRT or touch the anode 1 Slide the CRT socket cable straight off the neck of the CRT 2 Removethe four mounting screws and the ground wire and lift the CRT off the bezel A Warning If you need to dispose of the CRT refer to the CRT disposal instruc tions in Bulletins Safety ip CRT 15 Replacement Note If you replace the CRT perform the voltage video and yoke adjustment procedures See Voltage Video and Yoke in Adjustments mn Floppy Drive 16 Floppy Drive Before you begin e Remove the cover e Discharge the CRT e Remove the logic board A warning This product contains high voltage and a high vacuum picture tube To prevent serious injury review CRT Safety in Bulletins Safety A Warning Never use a grounding wriststrap until after discharging the CRT ili Floppy Drive 17 Remove the four mounting screws and slide the floppy drive out of the chassis Replacement Note Before you install a replacement drive remove the dust shield if there is one mn Chassis 18 Chassis Before you begin Remove the cover Discharge the CRT Remove the logic board Remove the power sweep board Remove the floppy drive A Warning This product contains high voltage and a high vacuum picture
16. tube To prevent serious injury review CRT Safety in Bulletins Safety ili Chassis 19 A warning Never use a grounding wriststrap until after discharging the CRT Remove the five mounting screws and lift the chassis off the bezel mn Service Source Upgrades Macintosh Plus n Memory Upgrade 1 Logic Board Memory Upgrade Before you begin e Remove the cover e Discharge the CRT e Remove the logic board A warning This product contains high voltage and a high vacuum picture tube To prevent serious injury review CRT Safety in Bulletins Safety A Warning Never use a grounding wriststrap until after discharging the CRT ili Memory Upgrade 2 Note You can configure the Macintosh Plus with 1 MB 2 5 MB or 4 MB of RAM The standard 1 MB configu ration has a SIMMs resistor installed in R8 and four 256K SIMMs in both banks To add memory you must install SIMMs and remove the SIMMs resistor Note The Macintosh Plus requires 150 ns or faster SIMMs RAM speed is indicated by the xx number after the manufacturer s part number 15 indicates a 150 ns SIMM quip Memory Upgrade 3 Clip one end of resistor R8 and move the resistor away from the clipped lead Replacement Note You can retack the resistor later if necessary 2 5 MB RAM Upgrade Install two 1 MB SIMMs in Bank A and two 256K SIMMs in Bank B 4 MB RAM Up
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