Pole Position: I got a heartbeat...but now garbage on the screen

Bullwinkle

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Pole Position: I got a heartbeat...but now garbage on the screen

Hi... I've been working on resurrecting a Pole Position for a bit now. here's what I've done:

collage.jpg


In addition to the above repairs, I've re-seated all eproms/ram/processors and checked for corrosion. All chips look ok. That being said, as soon as I hit the power, I get the following screen:

screen1.jpg


Or if I shut down and restart..maybe this...

screen2.jpg


At one point I had letters repeating horizontally across the screen and scrolling to the left. Anyone have any ideas where I can go from here?

Edit: I've also check voltages on both boards to the +5vdc test points and i have 5.023 to 5.025vdc on all testpoints.

Thanks.

Tom
 
Try one different z80 cpu chip first. Then if you still get the same message I'd try locations 1, 12, 27. Do you get the same error message with a different video board?
 
Yes, I tried 2 video boards, both gave same RAM 127 message then the screen does what's posted in the pics above. I did try a 2nd z80...I think I have a few more.. let me try them..then I'll try the other chips

Thanks Ken
 
Ken, it was indeed a z80 issue, but also had a RAM 3 error. This is what I have now...

poleposition_better.jpg


sorry bout the blurry pic..but if you look at the player's car, it's missing some colors. a few of the other cars are missing some color too. Also, the accelerator seems stuck down, but when the game is over...i can use the steering wheel to select the letters of my name and enter each one using the pedal with no problems... i'm getting close.. anyone have any suggestions?
 
Just the obvious..

check the accelerator pedal pot for the "stuck on".. they get lots of gunk in them.. and also seems to be when putting in your initials... the initials get entered when you let "up" on the pedal... I can check on mine tomorrow if still need to know...

and start adjusting the monitor colors to try to grab your missing ones..



good job on getting it back to life...
 
ok, the pedal issue is corrected, so now I"m just missing a few colors on screen. I also have a bad socket where one of the z8002 40pin chips sit. ..I've made a few jumpers to get around it for now, but I'll need to find a 40pin socket at some point. And, i pulled a ram chip (location 7H on video PCB) off another board and soldered it in place. at some point I'd rather replace the ram and socket it as well.
 
first off clean the tube face and adjust your focus...

then play with the color gains and see if you can get the colors back. ALso wiggle the video input connector where it plugs to the monitors chassis.. if a color comesa and goes youve got cold solder there on the header pins...



Your almost there!!!! BTW- what monitor is in this pp? please tell me its NOT a matsushita aka matSHITuba


You may still have a boarrd issue too causing some colors to be missing because i swear i see blue, green and red , just a little weak there in that pic...
 
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yeah..i have a G07 in there now. The colors missing are ONLY from the vehicles and a few of the signs... Red, Green and Blue are present in other areas so its most likely not a color drive on the monitor, my guess is I still have a slight issue with my video pcb. So i decided to test a few more boards, and about 4 boards into the testing, I lost power to the boards (only getting 1.2v instead of 5v) ... so now i think my ps has an issue. I rebuilt it, but the core ps is still 25+ years old. Any way to use a switcher in these things?
 
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yes.. a switcher upgrade is very common...


there are threads here on doing it....

basically running the +5 and grounds to the test +5 points to make sure the power is being distributed evenly..

do a search for the thread on it...

I have not done it myself...
 
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