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xodaraP

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Hi everyone,
I was asked to repair a box full of 4 slot MVS boards by an operator friend.

I pulled the first one out today and decided to start a log as I go and hopefully get at least a couple of these up and running (some are believed to be beyond repair but will be good for parts supply!)

Board 1 Fault: Video RAM Error - In progress

Board 2 Fault: Video RAM Error - Repaired!

Board 3 Fault: Fast Video Ram (8000 region) error - Repaired!

Board 4 Fault: Crosshatch of death - Repaired!

Board 5 Fault: Click of death - Repaired!

Board 6 Fault: Major corrosion. Both top and bottom boards beyond repair

Board 7 Fault: Major corrosion. Both top and bottom boards beyond repair.


Standard upgrades/cleaning for all boards:

- Batteries removed and coin cell holder installed

- Battery area scrubbed clean to remove any previous acid leakage

- Rechargeable CR2032 installed

- Board cleaned using Simple Green

- Flux residue cleaned using isopropyl alcohol

- Cart slots cleaned with isopropyl alcohol
 
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xodaraP

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Board 1

Replaced both 62256 surface mount video RAM (twice, the first replacement set was also faulty!)

Additional Fault: Video RAM Error at $8000

Fix: Replaced both fast video RAM (Sony CXK5814)

Additional Fault: Crosshatch of death

Current Status: Repaired 3 traces that all failed continuity test. Board is currently still not booting on any slot.

Tested top board. Slots 2 and 4 boot with graphics issues, no boot slot 1 and 3. No sound on any slot.
 
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xodaraP

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Board 2

Replaced both 62256 video RAM. Board now boots to crosshatch

Board is now working 100% on all 4 slots
 

xodaraP

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Board 3

Socketed both fast video RAM. Replaced 1x 6116 type RAM to repair

Repair complete. Board booting games on all 4 slots
 

xodaraP

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Board 4

Repaired trace destroyed by battery damage

Video RAM error reported

Replaced 62256 video RAM

Z80 error reported

Replaced Z80

Board still not booting any games

Tried previously tested/known working top board - all 4 slots working

Repair complete!
 

xodaraP

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Board 5

Clicks regularly on startup, does not proceed through boot process

In progress. Board was very dirty and has been properly cleaned before proceeding with repairs.

Click of death

Replaced work RAM - click of death on different colour screen

Replaced BIOS with UniBIOS and boots to crosshatch

Burned factory BIOS to replace dead mask ROM - now reports fast video RAM error

Socketed and replaced fast video RAM

Fast video RAM error expecting AAAA received AAEA

Metered out working board and found bad trace on pin 11 to LSPC custom

Repaired trace on underside of board

Board now booting on all 4 slots, repair complete!
 
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