Qbert alien language and double screen!

jonathan1138

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Hi. Got a nice Qbert in lately. After a few days, the game started exhibiting this behavior - seems like some alien language and double screen.

I switched the game on / off, only to lose the bridge rectifier on the power brick. Thanks to Riptor for the quick delivery - thats been replaced and the cab is no longer blowing fuses.

But i am left with this. I checked 5 volts (5.10 so thats good) and reseated chips. I notice that chips F 1-5 and H 1-5 (or around there) on the PCB are running a little hot to the touch compared to the others.

Any suggestions on how to fix this? Help would be appreciated - any lead please!

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Thanks.
 
Could be one of several issues. But to start, have you removed, cleaned the legs of, and reseated all socketed IC's, especially the ones that get really tarnished in the middle of the board if you have the board oriented horizontally? Reseating them alone may not be enough. Alien language and double image together is a clue - might be a bad decoder IC like a 74LS138/9.

Some of those chips do get awfully hot.

Bill
 
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I will pull ALL chips tomorrow and pray that has an impact. I removed some / ran sandpaper on them today, but it was maybe 4 or 5, not all.

If that doesnt work, i an not sure how to track it down. I am going to check with Riptor to see if he can take this one on.

Thanks!
 
probably a bad vram, or control logic to the vram. Do you know that the monitor is good in this game?
 
Is bad vram, or control logic to the vram, something on the main PCB?

As for the monitor - its quite possible its a monitor issue too - i mean, its dual overlay it seems - the alien language seems to be caused by the overlay.

I do have a Tron with a WG4900 chassis - i can swap them to see if the issue is still there - is that a good approach?
 
Is bad vram, or control logic to the vram, something on the main PCB?

I don't have a Qbert, but most likely (not sure how many boards it has....). I think Mr. Bill probably has it if it is a board problem - LS138 and LS139 is part of the control logic to ROMs and other chips. Could also be a dataline output stuck high on vram or other.

I do have a Tron with a WG4900 chassis - i can swap them to see if the issue is still there - is that a good approach?
If you've never tested anything else on the Qbert monitor, then yes, absolutely. Test tron on this display, and Qbert on that display. Seems a logical thing to do before hitting up Riptor. Do you have a nice long video extension where you can just swap the RGBSync cables between monitors, or do you have to physically move the beasts?
 
Lol. Yes i have to move the beasts. Less so the Qbert - it is accessible. The Tron on the other hand is in between and i will need to ease it out to get back there.

The Qbert PCB is fortunately just a single board by the way.

Guess i will swap the chassis tomorrow to see if the issue persists. Then, we can narrow it down to the PCB.
 
Do you happen to have a pattern generator? Last ditch effort to try and prevent you from doing all that work!
 
I will pull ALL chips tomorrow and pray that has an impact. I removed some / ran sandpaper on them today, but it was maybe 4 or 5, not all.

If that doesnt work, i an not sure how to track it down. I am going to check with Riptor to see if he can take this one on.

Thanks!

It does sound like you will need "professional help" from Riptor. :)

Bill
 
Swapped Chassis between the Tron and Qbert. The problem remains the same.

Still have to pull chips, but i am doubtful that will result in improvement. I think one of the boards chips is effed.

I have a message into Riptor requesting his aide! Thanks.
 
Hi, to post a followup.

Sent the main board to MrBill08 - he did an excellent job repairing this.

Enjoy playing it now, but sadly, the game is for sale! I ran out of room!
 
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