Re: Need help troubleshooting Robotron Board

If I were looking I'd be checking a few things:

- voltage levels (mainly +5V, at proc Vcc, other areas of the board)
- frequency of clock (at proc pin, video dividers)
- various reset signals
- chip select activity (both at proc and at eproms)
- r/w line activity (throughout)
- databus activity

I'd concentrate on the clock though -- you'd expect "garbage" on the screen
if things were "working" (but the proc wasn't coming up). So take a scope
and look at the clock freq/levels at the various points (also poke around
in the video chain).

Just some random guesses. The above is basically my "start of debugging"
for dead boards (since you've already looked at the watchdog). It is worth
poking around with the scope probe looking to see that all the sections
are alive.

Good luck! (post some more info based on the above)

Kurt

On Thu, Jul 14, 2005 at 03:14:50PM -0700, Matt Rossiter wrote:
> I haven't spent alot of time troubleshooting Williams boards, so I'm hoping someone might be able to help me.
>
> The game won't boot up. It just comes up with a Green screen. No rug pattern or anything. Here are the tests I've done so far.
>
> 1) Ram test with Fluke 9010a - passed
> 2) E and Q circuit - looks good
> 3) Watchdog is stuck low - disabled the watchdog circuit, Same Problem.
> 4) Tried Swapping rom board. Same problem.
> 5) Tried swapping video decoder roms, Same Problem.
> 6) All voltages are good.
>
> This board was working perfectly for weeks, then suddenly died. So I don't believe there are any bad traces or connectors.
>
> Can someone give me some suggestions?
>
> Thanks
>
> Matt

-- 
/**
 * Kurt Mahan   kmahan@xmission.com
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 * "Did I say that out loud?"
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