Tron repair help needed - ROM errors!

Jconnell

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Donor 2018
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I have a vintage Tron machine and when I fire it up I get multiple RAM and/or ROM errors. Generally, it's D2 and D5 ROM errors but I sometimes get B2 RAM error as well as random D4, D6 and D7 ROM errors. Heres's what I've done:

1) reseated the ROMs and verified that they're all the same version 6-25.
2) checked the voltage at pin one at each of the ROMs and made sure it was 5.0 volts.
3) made sure all the cables were plugged in right. I have SCSI cables.
4) made sure the orange wire voltage is at 12.9 volts.
5) I did the ROM dip switch test on the sound board and got a glowing LED with no flashes.
6) the purple wire voltage is 4.7
7) the gray wire voltage is 4.2
8) the dip switches are correctly set
9) trying to get the board to boot so only the power cable and video out are plugged in along with all the SCSI cables
10) ROMs at G3 and G4 are getting 5.0v at pin 1 as are ROMs on the video generator board
11) there is a Peter Chou switching power supply installed in this game but the original connectors were changed out
12) the game worked when it was shipped from CA.

Any help would be greatly appreciated! Generally the boot is accompanied with a lot of screen garbage as shown in the photos.
 

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Last edited:
You mentioned the game worked when it was shipped... can I assume that the game arrived to your place (new purchase) and it has never worked properly?
 
That is spot on. Worked prior to shipment and has never worked once received. Totally perplexed.

Okay. In a perfect world I would test your board in a friends machine or test another board in that machine. I'm guessing this isn't an option.

Are all the games connectors original? If the game was really working prior to shipment my best guess is that something on the board is loose (like a chip got knocked out slightly) or my more likely guess is that the connectors to the board (all the molex 100 connectors) are old and outdated and need to be replaced. The move just highlighted how bad the connectors are.

I fixed up a beat up Tron and it worked for a year until it stopped. I sent my board out to CDJump to be fixed but board was fine. I replaced every connector in the game and it has worked rock solid for about a year now. Those connectors just loose connectivity over time it seems.

The only thing that throws me off is the ROM errors. Not sure if it would boot that far into it if connectors were your issue... but that is your easiest and cheapest next fix to try unless you want to send your board out for repair/testing first.

Also — you don't have the symptom for this but double check the coin door slam switch is open (put a paper towel in it to be sure). If that switch gets jammed up during moving it causes the board not to boot or to land in a reboot cycle. Not your issue but double check anyway.
 
I agree with brainmegaphone. You aren't showing your location but if you're local to SoCal I'd be happy to help you diagnose using my Tron.
 
Update

Thanks to all who have helped. Looks like this is some sort of PCs issue as putting +5vdc on vbatt still didn't change anything. The original power board was bypassed by the addition of a switching supply except for the reset and vbatt circuitry and when I plugged the original 9 pin cable back in, the 3A suitcase fuse blew. Accordingly, I'm out of my depth since I'm in the Pittsburgh, PA area and don't have a known working set of anything to go off of. As such, I've sent the boards to cdjump for him to work his magic. Keeping my fingers crossed!
 
Thanks to all who have helped. Looks like this is some sort of PCs issue as putting +5vdc on vbatt still didn't change anything. The original power board was bypassed by the addition of a switching supply except for the reset and vbatt circuitry and when I plugged the original 9 pin cable back in, the 3A suitcase fuse blew. Accordingly, I'm out of my depth since I'm in the Pittsburgh, PA area and don't have a known working set of anything to go off of. As such, I've sent the boards to cdjump for him to work his magic. Keeping my fingers crossed!

The hack job on the switcher install isn't going to make your troubleshooting any easier... but verifying the PCB works (or not) is a good first step. No matter what we will help you find the issue.
 
Issue resolved

Thanks to cdjump, the issue has been resolved and I have a working Tron! What happened was that a previously repaired bus bar broke during shipping. It was repaired again and everything works as it should. Thanks again to all who helped.
 
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