Qbert blank vertical strips

FedExin

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Hi, I've done some initial diagnosis on my qbert on a problem that arose after a cap kit for the CPU and sound board, SRAM upgrade, and installing a new switching PS. After all that work I let it run for a while. I came back to it with missing large strips of the pyramid missing, but not the q*bert logo. I narrowed it down to the socketed e10-11 and the perm mount e16. After removing and cleaning e10-11, I had the same result.

My question is, has anyone had the same problem and replacing e16 did the trick, and what chip should I order to replace it and from where?ImageUploadedByTapatalk1355683882.532232.jpgImageUploadedByTapatalk1355683895.082965.jpg
 
I ordered a couple 74LS273's from digikey. I'll post the results after I pop a new one in. I seem to be up a creek if the issue is with any of the surrounding IC's, I can't find them anywhere online:

74LS520 (E17)
74S161 (D17, F16)
 
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I seem to be up a creek if the issue is with any of the surrounding IC's, I can't find them anywhere online:

74LS520 (E17)
74S161 (D17, F16)

E17 is 74LS20 (very common), not 74LS520. Maybe you were seeing the S double... the 2nd time as a 5.

As fas the the 74S161, I'd put in a 74LS161. It's not quite as fast, but those look like they're just being being clocked by the H-blank... not particularly fast (so the extra speed of the S isn't needed, by my estimation).
 
Thanks for the heads up. I was reading from the schematic in the manual, it looked like a "5". Here's hoping the 20 pin E16 does the trick.
 
GAH. I got my package from digi-key yesterday..... I ordered surface mount chips!

Placed an order for some through-hole IC's..... Gah, humbug! :)

/nerdproblems
 
Replaced E15 as well. No dice. Anyone have an idea?

Here's a picture of the surrounding area. The only chips that look to have any visible affliction are g16 and g17. ImageUploadedByTapatalk1356560648.612857.jpg
ImageUploadedByTapatalk1356560669.548766.jpg
 
Experts; I'm willing to work toward a solution, but do you have any hints? I'm just replacing IC's at this point, based on fancy language in the schematics...
 
Here's a question, how can you test an SRAM (like the 4118's in E7 and E10-11) to see if they're working correctly?
 
Have a look at this thread it may help you and it may not. Worth a shot though.....\

It does have some links to helpful manuals.

http://forums.arcade-museum.com/showthread.php?t=249722

Thanks! I've been reviewing the troubleshooting and original manual, and I just found qbert.me as well.

On a lark, I swapped the two 4118's and lo and behold, I got a garbled but complete pyramid. So it appears that E7 is an issue. I'll be ordering some new SRAMs to replace them now.
 
Be sure to check those blue Lego block-like jumpers which set the foreground and background sprites. I've chased IC's around the board only to discover it was one of those damn shorting blocks not making a good connection.

FWIW I like to remove the originals and replace them with gold plated square post and new gold plated shorting blocks, end of problem forever.
 
That's a good point, I'll check the jumpers next. My new (old) mostek 4118A's came in the mail. I swapped out the two I thought to be a problem, and got a new problem, the game doesn't boot and just shows blocks of garbage.

It's been cold here lately and it was around 40F here when I swapped the chips. I swapped the old srams back in and got the same issue. I'll look at it some more when I get my workshop heated again, the propane heater I was using is kaput. Plus, I'm looking for one actually rated for indoor use.
 
Cold in California? Let me guess, 40's? LOL@! We're not going to break out of the 20's all week and we've got a good cover of snow and ice right now.

After handling the board swapping chips and you've got more graphics issues; that sounds much more like a jumper and/or socket issue. Logic faults usually aren't going to change with mere handling.

Keep us posted, it'll help someone else in the future.
 
That's the intent, Mike, to document this for future trouble shooters.

Yep, 40's are cold here in mid-state California. I grew up in the mid Atlantic area so I know about some cold, and I'm glad to be living in a more temperate area. :)
 
I finally got around to swapping the rams, but before I did I now have a new issue (of course) after having not touched a thing. It boots to gibberish blocks. I tested the fuses on the power block, they're fine. If I turn up the power on the PS the gibberish moves a bit.

I'm thinking it may not be getting enough 12v but how can I confirm?
 
Here's a pic of the garbage I'm getting now. This thing is whupping my tail.

2013-01-11-15.15.04.jpg
 
Do you want me to give you a hand in fixing this?
Do you have a logic probe?
I am current fixing my corrosion Qbert PCB. the machine is currently running on a spare PCB.
 
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