MK2 - UB11 and UB13 failed, game stops

[xodaraP]

Pin 26 may also not be getting the correct voltage if there is corrosion on the trace leading to the resistor - and given that line is CE (Chip Enable) it could absolutely be the cause of some of your issues

I would suggest checking to see if you are getting correct voltage up to the resistor

 

[mawrick]

Pin 26 may also not be getting the correct voltage if there is corrosion on the trace leading to the resistor - and given that line is CE (Chip Enable) it could absolutely be the cause of some of your issues

I would suggest checking to see if you are getting correct voltage up to the resistor

Will do a check again later after I put back the jumper wire, just to recap how it acts now.


with the jumper wire in place to cmos chip everything checks out in diagnostic, and the game runs attract mode ok (afaik), when trying to play it just doesn't act right.

I removed the jumper again and the game will power up, with everything green but with cmos error when cmos chip is removed - if I put back the cmos chip (without it getting power thru the jumper) the game goes back to the initial error of error on UB11 and UB13 (unsure if this might just indicate there is something wrong with the cmos chip itself or not.


I'v also noticed if I press start at the first graphics that are displayed initially it will trigger some graphical garbage on screen before it resets.


I think anyway I will put back that jumper wire between Max691 and cmos as that is the closest this board has been to a "working state".....before doing adittional troubleshooting.

 

[mawrick]

Tested again with some other cmos chips, which also seem to work ok, but still trouble.

Also the resistance between pin 28 and 26 of UJ11 looks fine, so should be ok.

Can this kind of problem be caused by "rom rot" ?.

I guess it's back to drawing board....(wherever that might be )