Rally-X Reset/Boot Up Error - Help Needed...

Alan173

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Wow...this repair has been kicking my butt and I'm looking for a few suggestions to point me in another direction. After everything I have gone through I'm thinking the custom chips are to blame and there are no data sheets for them...but being stubborn...I have tried to fix this boardset inside and out without much luck. Here are some details:

Power board confirmed working fine.
All voltages on all chips confirmed fine (5.1vdc).
No shorts or ground pins reading strange.
New Z80A in place...all signals seem fine...reset toggles from low then goes high when reset button is pressed, etc.
All new 4116 RAM in place...triple checked...sockets fine.
Almost all logic of all chips confirmed good. Gets a little crazy on chips like the 74LS139's but all outputs on all chips show activity where they should.
I have replaced 5A and 5B where I thought for sure I had a problem...no change.
All the 74LS157's seem to be working just fine.
I have been up and down the RAM/ROM circuit with a logic probe and can't seem to find anything wrong.

O.k...now Punt!

And that is about it for a quick summary - here is the sequence I get when I power up and the game appears to be stuck in the ROM/RAM test...it just does this sequence over and over:

http://www.youtube.com/watch?v=tRb9RUxMgbc

Any suggestions...ideas...all are welcome!

Alan
 
Last edited:
Custom Chip..

Looks like the custom chip to me... :cool:

I know the many custom chips on this boardset are often blamed for this game being stuck in the RAM/ROM test...especially the custom chip at 6P. If anyone has pin readings for this chip...please send them my way...
 
All sockets confirmed good at this point. Continuity and signals confirmed....no dead pins.

Still scratching my head on this board-set...

Alan

I have recently confirmed the NVC285 @ 2D was good. So that is one major custom chip out of the way. Been also playing with my newly acquired HP 10529A and all the chips I have been checking seem to be just fine. I still have a few more to go but don't believe I'm going to find anything...

Still trying...

Alan
 
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