Donkey Kong Repair #2

darthi8nt

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Received 2 boards from member Phetisboy for repair. A 2 board Donkey Kong and a 2 board Donkey Kong Junior.
First board was Donkey Kong Junior:
Problem: Was told board reset after level 1 was played. I cleaned the Z80A and reseated the Eproms Played game for several days and never had the issue of resetting occur. Checked power on the edge connector and all the caps and power to the IC chips everything was in normal specs. Even plugged it back in today after it had been sitting around for a week while I was in Tenn at my mothers funeral. No Charge to the customer for board work.

Second board was regular Donkey Kong:
Problem: Board would not boot up at all even though it had power.
Soultion: Found Broken Transistor leg at Q8 on the CPU Board. Replaced with new transistor still not booting. Checked rest of transistors and diodes and did ESR checks on caps and still nothing. Checking Video board found missing IC chip at location 1E it had been socketed and the socket on one side was broken. Replaced broken socket with a new socket and looking at the schematics found the missing chip to be 10136 replaced chip and turned game back on and now we have video. Coined the game up and the game still had problems this time the game would freeze up after you lost all your lives and sometimes if I shook the pcb board the game would unfreeze. The solution was to start checking the Eprom Chips for corrupt data. The culprits turned out to be 2 bad Eproms on the CPU board. 5C was corrupt and I was able to reprogram that chip by erasing it and reprogramming the chip. Next, 5E was bad I had to replace with a brand new chip which I programmed cause the old Eprom wouldn't allow me to reprogram it. After all that I retested and now the game was playing great through all levels. I even shook the board to see if anything would happen and nothing kept playing normal and I played for hours. I love Donkey Kong its so fun. P.S installed new pots on the video board because the old ones were ready to break off the picture would jump if you barely touched the pot.
 
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Here are some pics of the broken socket and then a pic after I desoldered it.
 

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... sometimes if I shook the pcb board the game would unfreeze. The solution was to start checking the Eprom Chips for corrupt data.
If shaking unfreezes the game, that would imply some sort of mechanical failure. What's the correlation between this and the corrupt EPROM data?

LeChuck
 
I should be more specific. Yes shaking refers to a mechanical failure but the shaking I was doing refers to a pushing of chips and a wiggling motion of the chip back and forth thus causing the reseting of not the entire game but the continuing of the gameplay which told me I had a problem in one of the chips wheather the leg was bad or the socket was bad after pulling all the eproms and reading the data on them the only faulty chips were the 2 mentioned and the sockets tested good I think the 5E chip had a bad leg and when I wiggled or shook it the game chip made its brief electrical contact and continued to play until you changed screens then it locked up again. Replacing with a brand new chip and rewritting the data to those 2 chips resolved this problem.
 
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