Repair help: Difference between revisions
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(Simple VRAM error troubleshooting) |
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==Video RAM error== | ==Video RAM error== | ||
*Address between $0000 and $7FFF: Check [[CXK58257]] | *Address between $0000 and $7FFF: Check [[CXK58257]] [[VRAM]] chips next to [[GPU]]s. | ||
*Address between $8000 and $86FF: Check [[CXK5814]] | *Address between $8000 and $86FF: Check [[CXK5814]] VRAM chips. | ||
*Read high byte is different: check RAM chip with highest number. | *Read high byte is different: check RAM chip with highest number. | ||
*Read low byte is different: check RAM chip with lowest number. | *Read low byte is different: check RAM chip with lowest number. | ||
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==No sound== | ==No sound== | ||
*Backup RAM corrupt, '''SOUND_STOP''' ($D00046) is non-zero. Clear Backup RAM. | *Backup RAM corrupt, '''SOUND_STOP''' ($D00046) is non-zero. Clear Backup RAM. | ||
*[[Power amp]] is | *[[YM2610]] has no clock, bad control signals (/CS mainly), or dead. | ||
*[[YM3016]] has cut traces to YM2610, or dead. | |||
*Low sound level: recap audio section. | |||
*[[Power amp]] is fried. | |||
*Unplugged or faulty [[NEO-CDD boards|NEO-CDD board]]. | *Unplugged or faulty [[NEO-CDD boards|NEO-CDD board]]. | ||
*Dead op-amps. | |||
==Z80 error== | ==Z80 error== | ||
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[[Category: | [[Category:Repairs]] | ||
Revision as of 02:44, 23 December 2015
MVS
Video RAM error
- Address between $0000 and $7FFF: Check CXK58257 VRAM chips next to GPUs.
- Address between $8000 and $86FF: Check CXK5814 VRAM chips.
- Read high byte is different: check RAM chip with highest number.
- Read low byte is different: check RAM chip with lowest number.
- Read byte stuck to $FF (bad /OE ?), only a few bits different (traces cut ?), random address (floating /OE, /CE ?)
No sound
- Backup RAM corrupt, SOUND_STOP ($D00046) is non-zero. Clear Backup RAM.
- YM2610 has no clock, bad control signals (/CS mainly), or dead.
- YM3016 has cut traces to YM2610, or dead.
- Low sound level: recap audio section.
- Power amp is fried.
- Unplugged or faulty NEO-CDD board.
- Dead op-amps.
Z80 error
Can be caused by bad components / continuity with the following:
- Z80 <-> SM1
- Z80 <-> RAM
Second generation specific (todo: get pin numbers in a nice table)
- Z80 <-> NEO-D0 (NMI,A2-A4,IORQ)
- Z80 <-> NEO-C1 (Z80 D0-D7)
- NEO-D0 <-> NEO-C1 (Z80R,Z80W,Z80CLR,SDW)