Trak 10 / Gran Trak 10 PCB Help

GothGirl

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Howdy!
Have this project Trak 10 that has come a long way, yet still isn't working fully and my limited PCB repair skills are maxed out I am afriad. I have gotten it from a state of total garbage on the screen to a track, a timer, and a car. The timer upon start up is scrambled (this is a new issue, so a gate somewhere might have failed)... but the game coins up and tries to start. As you can see on the video, the car just scrolls in its little boxed off area but doesn't move. The logic probe has gotten me to this point, but I wonder if one of the custom security chips are failing here which is my issue. Also there is no sound. Also notice the large amount of traces that are not mine, but I wonder if some mod was done to this PCB at some point... it seems like there were a few common to this board back in the day. Any and all help appreciated!
Cassie


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Your car has a positioning issue. I'd look for anything in the schematics that relates to positioning of the car horizontally and vertically, using a probe to see if anything (like a counter) has floating or stuck outputs. Your sound problem may be to result of a bad amp. I wouldn't touch the mods on your 7410 IC, I'd actually document them in full. Perhaps it's that bonus track mod?
 
Might not help with your issue specifically, but obligatory link to Ed Fries' great Gran Trak 10 repair article. (Which anyone with a GT10 should know about.)

 
Might not help with your issue specifically, but obligatory link to Ed Fries' great Gran Trak 10 repair article. (Which anyone with a GT10 should know about.)

Yeah I looked through it, it's pretty great… it's also what lead me to think my issue is those silly custom security chips 💩 but my hope is someone smarter than I knows some other tid bit
 
Do you know blinddog (Matt) up there? Golden age guru…
 
Hmmm…looks like he was having trouble accessing klov a while back so it's doubtful pinging him would work. @blinddog you there? Maybe check with anyone on SMAC?
 
It does look like the scrolling could be an issue with the vertical motion. I'd start by checking the counters at J7 k7 and L7. Those 9316/74161 are problematic and it wouldn't surprise me. You can test the outputs and see if they are pulsing. The service manual also seems to go over further test procedures for the counters on page 2-19 under TP82.
I do have a parts board with the custom chips, I could part with them If needed, I'd have to check them. They seem pretty reliable in my experience but I'm sure they do fail.
The mod is probably for free play. It looks like the jumpers go to chips dealing with coins and the start signal.
 
I have a board with the same issue, i think it's the right custom (yours haas a black X on it, did some previous owner perhaps already determine that it was bad?)
 
I have a board with the same issue, i think it's the right custom (yours haas a black X on it, did some previous owner perhaps already determine that it was bad?)
that is what i am thinking.... although the ROM has an X and it is fine, maybe someone reburned it tho
 
If you're having custom problems, look at the Lemans schematics -- it does pretty similar stuff but with discrete components instead of the hybrids.
I'm pretty sure I have a Trak 10 somewhere where someone replaced bad hybrids with daugherboards, but I prob haven't seen it in 20 years.

In any case, if the box isn't moving, your issue is likely with what they call the "window" circuit in the manual -- the window isn't moving.
 
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