Sorry: Pole Position Reset

rcranetx

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First, I've searched high and low and have seen the many different posts on PP and what a difficult game it is to work on. I didn't listen and am already at wits end and don't even have self test up.

Here's what I have done:
1. Sense mod
2. Both boards read 5.1v
3. Power and grounds tied together from test points
4. Replaced Z80 (sound) and socket
5. Replace 7H (105) and 7F (116) Roms
6. Replaced 6161 RAM at 7E
7. cleaned pins and Re-seated all chips
8. replaced chips in WDR and POR circuit (161, 259, 138
9. Checked to insure all Customs are in the right spot
10. cleaned edge and connector

I have not replaced the big blue caps yet due to the fact that my 5V is stable (and is not moving at all / via scope).

WDR looks to be doing what is is supposed to be doing but RESET is toggling low in a repeatable fashion. I've tried tying WDR LOW as well as RESET high but nothing, nada, zilch. I expect even more difficulty once I do get to a test screen but can someone spin me around a few times and point me in direction to get me out of my RESET LOOP?

Cheers everyone!
 
pole position reset

Morning,
Have you looked at the reset button on the board? They are notorious for going bad.
Also check the Crystal oscilator circuit. I would also go ahead and replacw the Big Blue(s) given the age of the game and all of the posted problems that it causes. And Cap the AR boards.

RJ
 
did you test the voltage at one of the ROM's or other chips? I have seen one post where someone said they worked hours on a machine just to find that the psu was outputting the correct voltage but it was low at the ROM's.
 
Thanks RJ. No reset button populated.

Voltages good at ROMs too.
 
How fast does it reset? I had one once that had a faulty zener diode and it would switch on and off about once a second.
 
I can't recall. I'll have to take a look at a board. It's been a while. I do not believe it was in the battery circuit.
 
Thanks! I only spot two Zeners. The before mentioned CR6 and one in the Video PCB Power Input diagram. CR6 appears to be bad as it reading small resistance in both directions.
 
Pole board reset

I would also go ahead and replacw the Big Blue(s) given the age of the game and all of the posted problems that it causes. And Cap the AR boards.

RJ[/QUOTE]

Over time the caps fail(dry out) to properly filter the DC and basically pick away at the IC chips.
Spikes, ripples,drops in voltage on the AR boards will chip away at the TTL IC's.I have checked the caps with a cap checker after removing them and a fair amount showed bad.

Unless you have a logging scope you can miss some of the ripples and dips. Or you can stare at the trace for sometime. The Big Blues had a tendence to loosen up if they were banged around.

Dose the board reset happen after a few minutes? Check for componets heating up. Freeze mist is a good tool to help in Isolate a part going bad.

I also wear a ground strap when handling the boards.



RJ
 
Check the service switch. My Pole Position failed to work until I removed the service switch. I'm not certain if the switch itself was bad, or if someone had hacked it. Either way, unhooking it seems to have cleared up my problems.
 
Thanks for the tips everyone. I'll keep plugging along. Zener didn't do it. Will look at the switch as well as look at removing everything except the 5V to the board to see if it is resetting by itself or if there is something else (cabinet/harness) causing it too. Will also start replacing sockets...
 
After many starts, stops, and cursing, I found that the ROMs didn't match. The culprits were actually the PROMs from the factory. After replacing those with 2764s, I can now get to the test screen. ROMs OK, RAMs OK, everything OK. Accel is moving and game will not boot to game mode; just blank screen.

I think the accel is causing some issues as its never quite still in test mode.

Thanks,
Russell
 
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