MV1-1
Back up RAM error. 5555. 0055. Alot of oxidized solder around (a leaking) battery area.
Desoldered battery. Cleaned up and neutralized oxid.
Patched 4 broken traces on upper BRAM.
Booted up to ... Work ram error (both).
Adress ****** (don't remember) Write 0000. Read 1111.
One step back since MVS tests must pass work ram before back-up RAM.
After this a circus followed with me changing RAM-chips and getting various work- and back-up RAM errors. Sometimes all tests did pass with diagrom - but not with stock bios or unibios.
Checked select line and data lines: OK. Nothing made any sense.
Suspected and redid my trace-work. Also found new rotten trace AS04 to LS32 chip. This brought stability and I could boot to a crosshatch with stock bios.
When playing a game all sprites had vertical lines. A quick google revealed that this is caused by problems with the c-rom. Checked traces around connector. Found 3 bad traces. But patching these brought no change.
I made this pin-out to know where to look ...
(CR is on the cart slot, next column is on the board (cap side is the side on the slot module which has a capacitor. Resistor side ... Final column is ZMC2.)
Summer on cartridge slot to ZMC2 chip: CR30 to pin 45 was bad. Patched this and vertical lines were gone.
Final inspection; discovered 6 broken traces from the dip-switches. Fixed these as well. Then had a beer.
Back up RAM error. 5555. 0055. Alot of oxidized solder around (a leaking) battery area.
Desoldered battery. Cleaned up and neutralized oxid.
Patched 4 broken traces on upper BRAM.
Booted up to ... Work ram error (both).
Adress ****** (don't remember) Write 0000. Read 1111.
One step back since MVS tests must pass work ram before back-up RAM.
After this a circus followed with me changing RAM-chips and getting various work- and back-up RAM errors. Sometimes all tests did pass with diagrom - but not with stock bios or unibios.
Checked select line and data lines: OK. Nothing made any sense.
Suspected and redid my trace-work. Also found new rotten trace AS04 to LS32 chip. This brought stability and I could boot to a crosshatch with stock bios.
When playing a game all sprites had vertical lines. A quick google revealed that this is caused by problems with the c-rom. Checked traces around connector. Found 3 bad traces. But patching these brought no change.
I made this pin-out to know where to look ...
(CR is on the cart slot, next column is on the board (cap side is the side on the slot module which has a capacitor. Resistor side ... Final column is ZMC2.)
Summer on cartridge slot to ZMC2 chip: CR30 to pin 45 was bad. Patched this and vertical lines were gone.
Final inspection; discovered 6 broken traces from the dip-switches. Fixed these as well. Then had a beer.
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