Pole Position I board issues - Ram 8 error

Hemiguy345

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Yet another Pole Position question to add to the forum. Searched the forum on this and other ram errors and I'm stuck. Here's what I've done thus far:

- Cleaned the edge connectors
- Checked all +5v test points to verify getting at least 5 volts
- Replaced 7E with Dallas battery backed chip, still no difference.

One thing to note on the cpu board that the red led is not lit whereas on the video board it is lit up. Any hints as to what might be failing to cause that? I'm guessing it's somehow related to some other component on the board that is shot.

I know these are a pain to work on, but it's getting colder up here anyway so at least I have something to play around with during the winter :)

Thanks
 
Does the screen look all garbled when it powers up? I have had this issue with my PPII boards for a while.. although it is not always ROM error 8, sometimes others. But the fix has always been to remove the main edge connector, and gently blow in it as you would have into an old NES cartridge.
I need to replace the edge connector, and hopefully that will eliminate the need to do this; though I do not have this issue with my PP boards.

I am not sure why you aren't getting the red led to light up, but it could be a connector prob
 
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Did you test each board for good ground input ? There's a diode and a resistor to the right of the LED on the CPU board, check the diode. It sounds alot like you have a power issue.
Is the egde connection good on the board ? Try running seporate grounds and 5+ to the test points on BOTH boards and see if that makes a difference.
 
Did you test each board for good ground input ? There's a diode and a resistor to the right of the LED on the CPU board, check the diode. It sounds alot like you have a power issue.
Is the egde connection good on the board ? Try running seporate grounds and 5+ to the test points on BOTH boards and see if that makes a difference.

This. The diode and resistor he's talking about are fried on ALL of my board sets.

I've since decided to remove the +5 and +sense lines from my machine and I run an ATX power supply to +5 and GND test points on both boards. After doing that, most of my boards fired right up (granted, still with errors... I mean, these ARE PP boards after all) but the LEDs are lit and now I know my boards aren't dead (just broken... difference in my head).

In short, yeah... you're losing that +5V somewhere on the board that doesn't have the LED lit up.
 
Did you test each board for good ground input ? There's a diode and a resistor to the right of the LED on the CPU board, check the diode. It sounds alot like you have a power issue.
Is the egde connection good on the board ? Try running seporate grounds and 5+ to the test points on BOTH boards and see if that makes a difference.
The board comes up with just the ram 8 error right now. The edge connectors have been previously repaired using the copper foil stuff so they look pretty decent, although you can tell in the past there's been some previous burnage.

I'll check the diodes and resistor to see if they are functioning and the ground issue.
 
Check for a low on the cmosramcs, ( pin 18 or 20 on the cmos ram ) if it isn't low that will cause the ram8 error, goes back to the power up circuit of Q2,3 and 4 which is close to the battery and is one of the first to go when the battery leaks.
Dick
 
The board comes up with just the ram 8 error right now. The edge connectors have been previously repaired using the copper foil stuff so they look pretty decent, although you can tell in the past there's been some previous burnage.

I'll check the diodes and resistor to see if they are functioning and the ground issue.
Okay, got some time today to at least check the resistors. I'm not 100% sure how to check the CR2 diode. Anyway, here's what I tested by the LED:

R1 - 217 Ohm, manual says 220 Ohm
R174 - 29 k Ohm, manual says 33 k Ohm
R169 - 104 k Ohm, manual says 220 k Ohm
R170 - 388 k Ohm, manual says 390 k Ohm

So based on the above I would assume I should replace R174 and R169 based on the tolerance for these? For R169 I quadruple checked it since it was such a big difference. Anything for this resistor that would cause a false reading? I tested these all the same way with the power off, and connected to the board.
 
Check for a low on the cmosramcs, ( pin 18 or 20 on the cmos ram ) if it isn't low that will cause the ram8 error, goes back to the power up circuit of Q2,3 and 4 which is close to the battery and is one of the first to go when the battery leaks.
Dick
I'm not sure how to test this. I'm guessing I should check the resistance level versus a high reading? So how would I connect my test probes?

I did take a peek at the Q2 and Q4 connectors. One of them looked like they had been replaced before as the solder joint looked pretty clean. The other looked like it had been exposed to a battery leak as it's joints looked dulled/greenish looking. If I have to order some resistors would it make sense to just replace these at the same time?
 
I'd say you should remove those two with the off readings... if they test good on the board, so be it.

but if they test bad.. de solder and remove them, then test again...
 
Well, I replaced resistors R169 and R170. I also went ahead and replaced the diode.

Checked 7E pins 18 and 20 for less than 1v and verified that was correct.

So I still don't have the led on the CPU board lit yet. I checked the volts at the LED itself and got a reading of .96 Volts.

I did the same check on a pole position II board that I have laying around that at least has the LED lit on both boards , measured in the same spot and got a reading of around 1.60 Volts.

Obviously as it's been already pointed out there's not enough power getting to the LED on the cpu board. If there's anything else I should check let me know.
 
Ok.... granted this may sound a little stupid at first..... but have you tried swapping the LED with the one that comes on ?
 
Yea that's where I'm heading next on this. I'm going to replace the LED and the resistor that feeds power to it since I didn't replace that with the others last time.

Hopefully this week I can get back to it. I'll report back where I'm at next after that.

Thanks,
 
Replaced R1, LED still not lit up. So went ahead and put a new LED in it and bingo it lights up now.

Still get an Ram 8 error though, but at least its encouraging that I'm making some sort of progress fixing something, although at a slow pace it seems.

So I'm going to revisit Dick's suggestions and focus on 7E and Q2,Q3 and Q4 areas. Thinking of reflowing some solder to the socket itself first and go from there.

Anyone know which location on 7E to test for 5v? I want to verify that 5v is getting to the chip.
 
Check the resistors supplying base current to the RAM if you don't have a solid 5v to the chips.
I would also run 5v and grounds to all the test points via hard wire to make sure you have a good connection to all area's of the board.
 
Well finally got back to this after the holidays this week. I ended up fixing the Ram 8 error by doing the following:

- Replaced wiring harness as it was pretty hacked, with a different one.
- Found out the other harness was setup for a switcher, so I figure why not, having power issues anyway.
- Converted to switcher, ran wire to all +5 points, and gnd. Hooked up switching power supply to wires.

Now it comes up with a RAM 6 error. Unfortunately this chip isn't socketed so before I go out and order a replacement 2114, anything I should double check that would cause this new error?

I was thinking of ordering the chip and a socket from coinopchips and seeing where that leads me next. Thanks for all the help so far, I'm getting closer it seems.
 
Well, I spoke too soon. Found I had put in the ram 8 chip in incorrect which was giving me the ram 6 error.

After I sorted that out still getting the error. At this point I think it's time to look into getting the board fixed by a pro.
 
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