Pole Position questions ( so what else is new?)

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Pole Position ram 8 error

I've been working on my Pole Position cockpit after finally acquiring a wiring harness. After successfully repairing the Matsushita monitor I've moved onto the pcb. I won't go beyond what knowledge I have and I know this board can very possibly be a real headache, but I thought I'd try a few things. Initially when powered on, the cpu board wasn't getting 5 volts and the 5 volts was very low as measured at the ARII. Without a load I could get the 5 volts from the ARII and I got the same results when swapping them so I knew it was something on the CPU dragging the 5 volts down from its ARII board. A visual inspection found CR2 to be suspicious looking and after removing it from the board you could see it was physically damaged as well as shorted according to the meter. Definitely bad. After installing a replacement, my 5 volt leds on the cpu came on, but only briefly and the diode crapped out again. I then tested it with a diode leg taken out of circuit and was able to get 5 volts to the cpu, although it was 5.5 with the adjustment down all the way on the ARII. I can tell my edge connectors need to re replaced so that's my next task. Am I correct in thinking the bad edge connector is causing CR2 to die? The boards and harness are from separate machines so no way to really know what killed the pcb before I got it with the bad CR2. I've already rebuilt both ARII's and even replaced both Big Blue caps. I need to also get some copper foil and touch up some of the card edge pins on the cpu pcb as well. If anyone can confirm I'm on the right track or offer any other ideas I'd appreciate it. On a "positive" note, the brief seconds I ran it without the diode, I have a ram 8 error. Joy. :) Thanks!
 
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I've been working on my Pole Position cockpit after finally acquiring a wiring harness. After successfully repairing the Matsushita monitor I've moved onto the pcb. I won't go beyond what knowledge I have and I know this board can very possibly be a real headache, but I thought I'd try a few things. Initially when powered on, the cpu board wasn't getting 5 volts and the 5 volts was very low as measured at the ARII. Without a load I could get the 5 volts from the ARII and I got the same results when swapping them so I knew it was something on the CPU dragging the 5 volts down from its ARII board. A visual inspection found CR2 to be suspicious looking and after removing it from the board you could see it was physically damaged as well as shorted according to the meter. Definitely bad. After installing a replacement, my 5 volt leds on the cpu came on, but only briefly and the diode crapped out again. I then tested it with a diode leg taken out of circuit and was able to get 5 volts to the cpu, although it was 5.5 with the adjustment down all the way on the ARII. I can tell my edge connectors need to re replaced so that's my next task. Am I correct in thinking the bad edge connector is causing CR2 to die? The boards and harness are from separate machines so no way to really know what killed the pcb before I got it with the bad CR2. I've already rebuilt both ARII's and even replaced both Big Blue caps. I need to also get some copper foil and touch up some of the card edge pins on the cpu pcb as well. If anyone can confirm I'm on the right track or offer any other ideas I'd appreciate it. On a "positive" note, the brief seconds I ran it without the diode, I have a ram 8 error. Joy. :) Thanks!

I had issues with voltage on mine because of the 5V sense. It was frieding the resistor and zener diode on the CPU board. Took that out of the picture (removed them from the harness as well as the +5 lines). Put in an ATX power supply and feed +5 and GND directly to all the test points on both boards. Brought my boards (that were close to running) up and let them run long enough to fail burn in (developed random RAM errors, like 23 and 15... crap like that).
 
Yeah I plan to definitely run +5 and ground loops to each of the test points on both boards, but I do plan to keep the AR boards in there. Hopefully with new edge connectors and pins annd jumping the test points I'll get the power situation stabalized.
 
Yeah I plan to definitely run +5 and ground loops to each of the test points on both boards, but I do plan to keep the AR boards in there. Hopefully with new edge connectors and pins annd jumping the test points I'll get the power situation stabalized.

Yeah, I left the AR boards in mine just for the audio, I wasn't having any issues with that part of the supply, but that 5V sense crap was frying the resistor behind the zener diode on every one of my boards... screw that. I figured I'd just take that out of the picture now so I don't have to worry about it re-frying something later.
 
Bumping this one with some updates.

After repairing the pcb's edge connector and replacing the wiring harness housings and pins, I have a solid 5 volts all across the pcb. I still have the ram 8 error and if I reset the board sometimes it will show what looks like bootup garbage before going right back to ram 8. Pin 18 of this ram showed low voltage but not pin 20 and if I'm understanding a previous post from Dick Millikan correctly, that means I need to look at the circuit providing power to this ram 8. I did however see a good 5 volts at the chip as measured on pin 24. I went ahead and purchased some replacement Dallas D1220AD rams and tried one today with no change. Any thoughts (other than I'm crazy for messing with Pole Position boards ;))?
 
No idea if you got it figured out already, but I'm trying to get a ds1220ab working in mine. I get the ram 8 error but if I put the 6116 back in, it boots fine. The dallas part apparently has a much tighter voltage requirement. If you never got this solved and haven't tried dropping a regular 6116 in there, give it a try.
 
The schematic shows pins 18 & 20 tied together, if one is high and the other low you need to run a strap between them, measure on the ckt side, if you have continuity there you probably have a bad socket.
Dick
 
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