Amiga 600 Troubleshooting Guide
Fault-finding on the Amiga 600. Commodore published no troubleshooting procedure for the A600; its A600 System Schematics has the board layout, parts lists and schematic.[1] The A600 keeps the Amiga 500's positions for the main chips (68000 at U1, Agnus U2, Paula U3, Denise U4, CIAs U7 and U8), so the chip-level checks in the Amiga 500 Troubleshooting Guide carry over for those parts.[1]
On an A600 that has not been recapped, recap and clean the board before deeper fault-finding; leaking capacitors cause most of the faults below. See the Amiga 600 Capacitor Replacement Guide.
First checks
[edit | edit source]- Look for capacitor leakage and corrosion before power-up, especially round the video encoder, the audio section and the reset circuit.
- Check for shorts between the supply rails.[2]
- Use the RGB output for testing. Composite and RF go through the CXA1145 encoder and its filters, which are the first casualties of capacitor leakage.[2]
- Measure the supply on the machine: +5 V, +12 V and −12 V. The A600 supply is rated 3.0 A on +5 V.[3]
Start-up colours
[edit | edit source]Kickstart changes the screen colour during its self-test. Commodore's own description, in the A500 service manual for Kickstart 1.3, runs dark grey (hardware set up), then red for a bad ROM checksum, yellow for an early exception, green for a memory problem, blue for a custom chip register failure, and light grey when the software is running.[4] Community references for later Kickstarts add light green for a CIA problem, and say a screen that stops at grey can mean a defective CIA.[5] A community troubleshooting list gives bad capacitors or a bad expansion card as common causes of a yellow screen.[6]
Symptoms
[edit | edit source]| Symptom | Cause found | Source |
|---|---|---|
| Black screen with sync, or no boot, on a board that has not been recapped | Leaking C612, the electrolytic in the 555 reset circuit; on the same board C611 was starting to fail and pulled the trigger signal low, and the 555 (U14) was heavily corroded. After replacing them the reset was reliable. | LinuxJedi[2] |
| RGB works, composite and RF are dead | The filter cans for the CXA1145 encoder (U12) destroyed by electrolyte. No replacement cans are made; repairers fit a Sony CXA1645, which has the filter built in, on an adapter. | LinuxJedi[2], Waveguide[7] |
| RGB missing its red component | Track damage from capacitor leakage | robthenerd[8] |
| One audio channel dead or distorted | Amplifier feedback loop on the right channel eaten away by leakage | robthenerd[8] |
| Crackling or distorted audio, bad composite, no boot | Leaking electrolytics; recap and clean | Hertell[9] |
| Hard drive not seen | Kickstart 37.299 has no support for the IDE interface or PCMCIA; fit a later ROM | Wikipedia[10] |
| Large CompactFlash card or drive misbehaves | The original scsi.device is limited to 7.87 GiB by CHS addressing | AmiBay FAQ[11] |
| Some keys or a group of keys dead | The membrane's ZIF contact end; its thin green foil covers fragile silver traces | Retrohax[12] |
Video
[edit | edit source]The CXA1145 at U12 takes the analogue RGB and produces composite video. LinuxJedi notes that it also buffers the audio for the TV output.[2] An exxos forum member warns that on the A600 the RGB output also depends on the CXA1145, so a failed encoder can leave no picture at all.[13] Check the encoder's supply and its RGB inputs and outputs before replacing Denise.
Chips by function
[edit | edit source]| Function | Position |
|---|---|
| Processor | U1 (68000, soldered) |
| Agnus | U2 (8375) |
| Paula (audio, floppy data, serial) | U3 (8364) |
| Denise (video) | U4 (8373) |
| Gayle (memory and I/O card interface, IDE) | U5 |
| Kickstart ROM | U6 |
| CIAs | U7, U8 (8520) |
| Video encoder | U12 (CXA1145) |
| Keyboard controller | U13 (6570-30) |
| Reset timer | U14 (NE555) |
| Audio op-amp | U15 (LF347 or TL084) |
| Chip RAM | U16, U17 (256K × 16) |
| Serial line driver and receiver | U28 (1488), U29 (1489) |
The 68000 is soldered, not socketed.[14]
Related pages
[edit | edit source]- Amiga 600
- Amiga 600 Maintenance Guide
- Amiga 600 Capacitor Replacement Guide
- Amiga 500 Troubleshooting Guide
- Amiga 1200 Troubleshooting Guide
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Commodore Business Machines, A600 System Schematics, PN-400422-02, April 1992, hosted at Amiga 600 System Schematics (400422-02). Specifications, PDF p. 3; board layout and key components, PDF p. 5; main board capacitors, PDF p. 13.
- ↑ 2.0 2.1 2.2 2.3 2.4 LinuxJedi, Reviving an Amiga 600: From Dead Video to a Clean Boot, 7 December 2025—link(accessed 2026-10-01)
- ↑ Amiga 500/600/1200 power supply—link(accessed 2026-10-01)
- ↑ Commodore Business Machines, Service Manual A500, PN-314981-04, October 1990, start-up sequence, PDF p. 33, hosted at Amiga 500 Service Manual (314981-04).
- ↑ Booting problems—link(accessed 2026-10-01)
- ↑ Amiga: Big Book of Trouble (Shooting)—link(accessed 2026-10-01)
- ↑ Amiga 600 video encoder upgrade—link(accessed 2026-10-01) The filters are "called Z221 and Z222" in the A600.
- ↑ 8.0 8.1 Amiga repairs—link(accessed 2026-10-01)
- ↑ John "Chucky" Hertell, Recapping, doing it right. Complete guide how to do it, 2016—link(accessed 2026-10-01)
- ↑ Amiga 600—link(accessed 2026-10-01)
- ↑ CF / SD and large drives FAQ—link(accessed 2026-10-01)
- ↑ Amiga 600 keyboard membrane fixes—link(accessed 2026-10-01)
- ↑ Help needed: A600 with black screen—link(accessed 2026-10-01) "CXA1145 is not for composite/RF only, A600 won't have image if it fails!"
- ↑ Amiga 600—link(accessed 2026-10-01)