Burgertime graphics and sound problem

skforty

New member
Joined
Feb 7, 2010
Messages
99
Reaction score
0
Location
redmond, Washington
I previously had a sound corruption issue with my burgertime. The main problem in the sound was caused by the sram @ 10H. The manual calls for the ancient Mostek 4118, I socketed and replaced with a 6116. I also had 2 eproms with corrupted data. This restored my audio.

Now the problem is that my sound works perfect if I boot the game cold, after about 3 minutes, the sound corrupts and then disappears. I have to let it sit for a bit to get the sound back, so it sounds like something is overheating? Maybe the audio amp?

---------------------------------------------------------
Graphical Issue:
Now the board is only showing half of the score and high score list, also anything green half red.

It seems voltage related because i can get it to appear normal if i leave the board on for a bit, then play wit the voltage. As i adjust the voltage within the 5.01-5.10 range you can see it having a direct effect on the issue. But if i let the board go cold, the graphical issue returns on the next boot.

I have a 2nd burgertime board that is working perfectly, I've swapped the sound cpu and sram etc, no change.

Maybe a flaky transistor?

Regarding both issues, I've done the following:

-Reseated the roms
-Recapped the audio section
-Cleaned the sockets
-Replaced the volume pot
-Verified the data on eproms
-Set my voltage (tested at the PCB).
-Replaced the 50pin IDC cables.


Any suggestions/help is greatly appreciated, thanks!



 
Come on guys! Help SK with his problem if you can! Free bump for a good guy. Hes always willing to help me when he can!

~Chris
 
Just shooting off the hip off the top of my head..
Something is crashing...

Have you measured the voltages when the sound crashes?
Is there a sip resistor tied to data lines close by?
Maybe a cab of freeze spray can isolate your problem or a can of air upside down..

Is the audio amp to hot to touch?
 
If I had to take a guess:
For the display issue of half the high score, it either sounds like a bad socket on the ROM's or Processors, or a bad line buffer (74LS245 or 74LS244) somewhere. I know the buffer for the main ROM's is 11A and maybe a couple of the data lines are flaking out after it warms up.
For the sound, it could be in a number of spots, the 8910's in 9F and 10F look like a posiblity. But so does the rest of the amplifier circuit. You could replace the 4558 or what I think is the 1181 (H3?) and see if that stops your audio from cutting out.
 
I was just thinking, if the audio amp was crashing due to over heating, I really do not think the sound would garble up before going quiet.

I could be a cap issues on the power supply..
A drying cap might give you the garble effect before the sound goes quiet..
 
Back
Top Bottom