Q*bert background jumbled

nutballchamp

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I'm stuck on fixing the jumbled background on my Qbert. Game plays find otherwise (except sound). Here's what I have done.

-Rebuilt power supply. I'm getting all correct voltages.

-Reflowed solder to filter board.

-Took out Clay Cowgill's Multi Qbert. I thought this might fix it with a new set of background roms. It still has a jumbled background.

-Cleaned, swapped and reseated srams e7 and e10-11. No change.

-As a test, I moved jumper Jp21 to Jp22. Background completely disappeared and foreground looked fine. See pics below.

Anything else to check? Thanks!

Jumbled background
IMG_0023-1.jpg


Jumper moved from Jp21 to Jp22
IMG_0021-1.jpg
 
Last edited:
Bump. I tested sram e10-11 and e7 in my Mad Planets and they are fine. How likley could it be a bad 74ls ram? Anyway to find out without a probe? I tried going into test mode and I get nothing.

Who fixes these boards?

Thanks.
 
74LS is not ram, they are TTL logic chips. Your problem could be low voltage, bad/dirty connections at sockets, bad ram, lots of things.
Its normal for the pyramid to dissapear when those jumpers are changed. You shouldnt be messing with the jumpers on the board. Post a good clear picture of your board so I can see if you are missing any jumpers or if maybe some are in the wrong place.
 
Did the game work correctly and then ended up in this state?

Or did you receive the game in this state?

Just trying to figure out whether something failed/changed vs. you received it in a bad/unknown state.
 
Thanks for the reply Riptor.

Below is a pic of my board. You can see hi-res pics here.

http://bpulliam.smugmug.com/gallery/9321739_6J2Wx/1/623293795_Mb3Ue#623293051_oMQun

Click on any pic on the right side and select the res size.

I checked the voltage on the board and I'm getting 4.9v on the 74ls logic chips. I'm getting 5.1v at the power supply. I cleaned the legs on the background roms, e10-11 and e7. Also checked continutity from the legs to the back of the board and they are all good. Wondering if I should still replace the sockets. Is there other socketed ram that could affect this problem?

IMG_0002-1.jpg


Thanks again.
 
The 4 chips in Row C 5-8 are also ram chips. I have seen this screen appear when you have a bad ram chip in E10-11. I think its a 4801 type RAM. As Riptor said I have also seen this happen when the voltage to the logic board is low, but you seem to have checked that already.

Luke
 
Did the game work correctly and then ended up in this state?

Or did you receive the game in this state?

Just trying to figure out whether something failed/changed vs. you received it in a bad/unknown state.

Yea, I have had this game for about 10 years and this problem happened a few years ago. Haven't touched it until recently.
 
The 4 chips in Row C 5-8 are also ram chips. I have seen this screen appear when you have a bad ram chip in E10-11. I think its a 4801 type RAM. As Riptor said I have also seen this happen when the voltage to the logic board is low, but you seem to have checked that already.

Luke


I swapped out e10-11 ram with my Mad Planets so I don't think it's the chip. Maybe the socket? I'll try cleaning the row c 5-8 rams. Thanks.

Is it possible it could be a logic chip?
 
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