Macintosh TV Troubleshooting
Fault-finding for the Macintosh TV, built on the symptom charts in Apple's Macintosh TV Service Source. Apple lists cures in order of likelihood: try the first, and if a replacement module does not cure the fault, refit the original before moving to the next.[1] Apple's charts stop at the module (analog board, logic board, CRT, drives, harness). The analog board has no published component list, so below module level work from the board itself.
The analog board carries mains voltage and the CRT's high voltage. Follow the CRT Discharge Procedure before working on it.
First checks
[edit | edit source]- Check the power cord and that the machine is switched on. The supply is universal, 100–240 V AC at 47–63 Hz, with no voltage selector.[1]
- Recap the logic board and tuner, and clean any electrolyte damage: see Macintosh TV Capacitor Replacement Guide.[2]
- Measure the PRAM battery on the 10 V DC range and replace it below 3.0 V.[1]
- Reset PRAM (Command-Option-P-R at startup, before "Welcome to Macintosh" appears). Apple lists this early for several display, CD-ROM and mouse faults.[1]
- Disconnect external SCSI and ADB devices.
Apple gives no rail voltages for this machine and has no voltage adjustment; its Adjustments chapter covers geometry, focus, video, convergence, geometric distortion and the yoke.[1]
Apple's symptom charts
[edit | edit source]Video
[edit | edit source]| Symptom | Apple's cures, in order |
|---|---|
| Screen black, too dark or too bright; sound and drives work | Contrast button on the front bezel; Brightness control panel; reset PRAM; check the yoke cable connection; video adjustments; analog board; CRT |
| Out of convergence (colour bleeds from text or lines) | Convergence adjustment; analog board; CRT |
| Single vertical or horizontal line | Analog board; CRT (but see the Trinitron damper line below) |
| Predominant colour tint, or colour cannot be adjusted | Video adjustments; analog board; CRT, if red, green or blue cannot be turned off with the controls |
| Screen bright, sound present, no picture information | Video adjustments; analog board; chassis harness cable; CRT |
| Picture breaks into diagonal lines, or rolls | Video adjustments; analog board |
| Black spots (burnt phosphor) | CRT |
| Screen jitters or flashes | Check nearby equipment is grounded, move electrical devices away and switch off fluorescent lights; check ground cables; disconnect the floppy, CD-ROM and hard drives; analog board |
| Out of focus | Focus adjustment; analog board; CRT only if one part stays out of focus with the controls at their limits |
| Flashing or wavy screen, or a high-pitched noise | Analog board |
| Raster too short, tall, narrow or wide | Size controls; analog board |
| Bad linearity | Video adjustments; analog board |
| Raster tilted or shifted | Grounding and interference checks; geometry adjustments; yoke adjustment; analog board |
| Raster distorted (barrel, corners not square, stretched at the top, sides not straight) | Grounding and interference checks; geometric distortion adjustments; analog board; CRT (rarely) |
| Raster not centred | Grounding and interference checks; centre controls; analog board |
Drives
[edit | edit source]| Symptom | Apple's cures, in order |
|---|---|
| Internal floppy drive does not work | Known-good disk; floppy drive; logic board; chassis harness cable |
| Disk ejects and a blinking "X" icon appears | Known-good system disk; floppy drive; logic board; chassis harness cable |
| Disk will not go in, or will not eject | Paper clip in the hole beside the drive; hold the mouse button down while switching on; remove the front drive bezel; floppy drive |
| Internal floppy drive runs continuously | Known-good disk; floppy drive; logic board |
| Hard disk does not work | Check no SCSI loopback card is attached; check external termination; hard drive; logic board |
| Internal or external SCSI works, but not both | External device ID above 0 and not duplicated; external terminator; SCSI select cable |
| CD-ROM drive does not accept a disc | Replace a dirty or damaged disc; remove the front drive bezel; CD-ROM mechanism; chassis harness cable |
| Volume control does not work properly | Reset PRAM; chassis harness assembly |
| CD-ROM drive does not mount | Check the CD-ROM software is installed; start up from a known-good Disk Tools disk or external drive; CD-ROM mechanism |
Peripherals and miscellaneous
[edit | edit source]| Symptom | Apple's cures, in order |
|---|---|
| Cursor does not move | Mouse connection; move the mouse from the keyboard to the rear ADB port (if it then works, replace the keyboard); mouse; reset PRAM; logic board |
| Mouse button has no effect | Mouse; logic board |
| Double-click does not open items | Remove extra System files; clear PRAM; as for the cursor |
| No response to the keyboard | Keyboard connection; keyboard cable; keyboard; logic board |
| ImageWriter or LaserWriter does not print | Chooser and control panel settings; known-good driver and system software; reset PRAM; printer cable (ImageWriter); logic board |
| Clicking, chirping or thumping | Analog board; logic board |
| Smoke or smell | Inspect the analog and logic boards for burnt components; analog board |
| No video, no sound, no drive activity | Power cord connected and switched on; power cord; keyboard; analog board; logic board |
| Sad Mac icon with black vertical lines and a screeching sound | RAM SIMM; logic board |
| Headphone jack does not work | Check the jack is seated; chassis harness assembly |
| Sad Mac icon | Known-good disk; disconnect internal and external drives and reconnect them one at a time; RAM SIMM; logic board |
For decoding Sad Mac codes, see Sad Mac Error Codes and the Sad Mac Decoder.
Things that are not faults
[edit | edit source]- A thin grey horizontal line across the lower third of a lit screen. Apple's chart says it "is inherent in the design of Trinitron monitors. Do not replace modules" (Symptom Charts p. 3).[1]
- Raster width that changes by up to 3/16 in at each side between Macintosh video timings (Adjustments, Geometry p. 6).[1]
- No television in a window. The TV picture always fills the screen.[3]
- No picture from over-the-air broadcasts. The tuner receives analogue NTSC only.[3]
TV tuner faults
[edit | edit source]The tuner is an assembly on the logic board, held by a twisted tab; to reach it, remove the I/O door and pull the logic board out from the back.[1] Its twelve electrolytics leak, and Recap-a-Mac calls the tuner "a bit of a corrosive nightmare".[2] If the computer works but TV does not, recap and clean the tuner board, reseat it on the logic board, and clean the aerial and RCA input jacks. If the remote control does nothing, check the infrared receiver connector on the analog board (Take Apart, Analog Board p. 7).[1]
Related pages
[edit | edit source]- Macintosh TV
- Macintosh TV General Maintenance
- Macintosh TV Capacitor Replacement Guide
- Macintosh TV Service Source
- Sad Mac Error Codes
- Macintosh Floppy Drive Maintenance
- Macintosh HDD Maintenance
- CRT Discharge Procedure
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Apple Computer, Macintosh TV Service Source (139 pp.), hosted here as File:Macintosh_tv.pdf (see Macintosh TV Service Source). Troubleshooting, General and Symptom Charts (printed pp. 1–17, PDF pp. 16–32); Take Apart; Additional Procedures, Battery Verification; Adjustments.
- ↑ 2.0 2.1 Macintosh TV, Recap-a-Mac—link(accessed 2026-09-30)
- ↑ 3.0 3.1 Mac TV, Low End Mac—link(accessed 2026-09-30)