Pole Position Bad Large Cars

scotth

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I recently picked up a Pole Position. It's my first real arcade machine. I have a MAME machine, so I'm not totally new...

The car sprites aren't showing up in the bottom 1/3 of the screen. According to the Service manual the "large car pictures" come from Custom ICs at 12J and 13J. The text on the start finish line is missing, and the billboards go blank when you get close to them. I've listed what trouble-shooting steps I've gone through. And would like some ideas to go through before sending the boards out for professional help. Thanks.

  • I ran the self-test, and it says everything is fine.
  • I checked the two chips at 12 and 13J they don't show any visual signs of damage. I removed and reseated them.
  • Someone put a switching power supply in the machine along the way, it powers the boards.
  • I messed around with the adjustment on the power supply, it seems happiest at about 5.1v.
  • When the power at the switcher power supply is 5.1v, I measure 4.5v t the +5 and ground on the side of the board. I can crank the switcher up to 5.5v to get 5v at the board, but still no large sprites.
  • I need to redo the edge connectors. They have some burn marks and solder repairs.

DSC_6203.jpg


There's a sticker with a 1994 date on the board. So it's been worked on at least once. This picture shows some of the newer looking chips on it and what is that blue wire, that is soldered to a few of the chips?
DSC_6206.jpg


Is this the battery I need to remove? Also, is the trace to the left of there bad?
DSC_6208.jpg
 
The burn marks on the edge connector are a result of having to crank the psu up to get 5v at the board. The volt drop in the wiring mean it will all get warm and eventually burn. You need thicker wires between the PSU and the edge connector.
 
I don't know that hardware but I can tell you that trace does look bad. The transistor (I think) above looks like it needs to be re flowed/replaced.

To be sure you can ohm the trace above the suspected break and the resistor r231 in the pic. I think that is where the trace goes but it is hard to see with it going under the other parts.
 
Personally I would start by testing the SRAM chips off the board, thats the most likely candidate.
 
Personally I would start by testing the SRAM chips off the board, thats the most likely candidate.

That burnt trace looks to me like a power rail and I would check/repair that first. If it is a power rail then power is not getting someplace it should.

I could be wrong and womble has more experience than I. I would listen to him closely but I think that trace is bad and a power rail.
 
You can always run auxiliary power & ground lines from the ps to the test points on the boards (I've seen many do this and I've done it as well in the past)... it gets the proper voltage to the different areas of the boards. I can also say from experience that you may want to look at the edge connector on the harness that connects to the boardset (both of them).. they are notorious for being problematic (i'm referring to the connectors themselves on the harness..not the fingerboards on the pcbs).

PP is a tough first game to go with but it's an awesome game once running.
 
I have had the same power issues with my PP. A lot of problems come from the power supply. You need to use a big enough PS as PP is a power hog. I use a PS from computer to provide sufficient power. You also need to deliver +5v and ground through the test points on each board to ensure correct voltages across both boards. Don't worry about the power at the edge connector just use the test points and it will most likely solve your issues.
 
I added a +5 and gnd to test points on both the cpu and video boards, still no large cars. I think I need to either get this test equipment or send the boards out.
 
I added a +5 and gnd to test points on both the cpu and video boards, still no large cars. I think I need to either get this test equipment or send the boards out.

No No NO.

With Pole Position, it is/will always be a problem child. So you are better off to get some test equipment and repair your self. Just do a search on Pole Position on the forums here and you will see for yourself.

start with the basic equipment, multimeter with beeper function, and logic probe with audio so you can hear the signals.

You can send it out and it will be repaired but what have you learned?

What will you do when it acts up again?

It most likely will act up again.

Now it is probably some kind of program/logic problem and if it is a ram chip you can just carefully piggy back one on top of the other to see.

I hope you decide to fix it yourself but the final decision is yours. If you are just going to sell it, maybe having fixed is better. If you are keeping it, I would take my time and post on the forums for help with where and what to probe, measure, poke, prod, wiggle, and slap.
 
No No NO....I hope you decide to fix it yourself but the final decision is yours. If you are just going to sell it, maybe having fixed is better. If you are keeping it, I would take my time and post on the forums for help with where and what to probe, measure, poke, prod, wiggle, and slap.

That's the best motivational speech I've heard in a while :)... I've already got the multimeter. Do they have a logic probe at Rat Shack? Or do I need to mail order one? Are there things in a probe I need to look for, or does anyone have a particular model I should look for.
 
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That's the best motivational speech I've heard in a while :)... I've already got the multimeter. Do they have a logic probe at Rat Shack? Or do I need to mail order one? Are there things in a probe I need to look for, or does anyone have a particular model I should look for.

I built my own at some point but finally got one with audio that is a big help when craning around a cab. I think I paid $23 with free shipping but here is one for $22 including shipping.


http://www.ebay.com/itm/LOGIC-PROBE...482?pt=LH_DefaultDomain_0&hash=item5d30e2fbc2
 
My logic probe arrived. I have the PP manual and Atari's Book. I want to test the Proms, rams and custom ICs in table 2-1 from the manual that are associated with the large cars, large signs and all cars & signs. Where can I find out how to interpret what the probe tells me?
 
Wish I could help, but I'm clueless about this stuff. Bump for ya though and good luck!
 
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