problem with my donkey kong

feynman

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my game has only been running a couple of weeks, it has doveloped a glitch...it flickers and resets itself, sometimes displaying garbage for a second, sometimes the picture flips upside down then freezes, sometimes it flips then back again...

it only ever happens in the first few minutes after turning on, never had it happen mid game, and it seem worse from a cold start...

http://www.youtube.com/watch?v=NRLt8ZKZJGM&feature=youtu.be

can anyone diagnose?

am running it in the uk from a step down transformer, using a new chassis via mikesarcade inverter board...

cheers
 
I've seen that happen with a power supply going bad. You will have to meter out the voltages of the power supply on the board to see if you are getting intermittent voltage drops or spikes.Dk chips measure out will be at 4.8 to 5.0 v dc across the chip. You may have faling caps on the board or in the power supply. Check the pots on the DK board for cracked or broken pots reflow the solder to them. A broken pot will cause that issue too along with a few IC chips.
 
thanks darthi8nt,

yesterday i removed all the socketed chips and cleaned the legs, so far that seems to have solved the graphical glitches, had no garbage, wrong colours or screen flipping...but the resetting problem is still happening, again its only shortly after power up...

i measured the voltages at the pcb end of the 9pin cord, the 5vs all looked good but the one that should be 24v was only 12v and the 12v ones were 10.x...

can you advise me what chips and how to measure, and how to identify the pots? i am new to this...

only obvious sign of damage i can see is one of the 103z caps is broken, a leg is detached with part of the ceramic attached, could that be the problem? can i repair it with solder or should i replace?

hope its not the PS cost me a fortune to get that over to the uk...

cheers
 
ok so while the game was running i was able to read drops in voltage on the 5v line that coinsided with the game resetting. reading was taken from the PS output before it reached the board, so i guess that means the PS is the culprit as there would be no feedback from the board??

also the coin counter is not working, probably because its not getting 24v...

can anyone advise on how i might repair this, i really dont want to get a new PS...

cheers
 
ok so while the game was running i was able to read drops in voltage on the 5v line that coinsided with the game resetting. reading was taken from the PS output before it reached the board, so i guess that means the PS is the culprit as there would be no feedback from the board??

also the coin counter is not working, probably because its not getting 24v...

can anyone advise on how i might repair this, i really dont want to get a new PS...

cheers

You probably just need to cap the power supply.

See here:

http://forums.arcade-museum.com/showthread.php?t=187033
 
its a pp-7b, pin 9 on the 9p reads 11.8v, pins 4 and 5 are 10.45v...according to the manual they should be 24v and 12v respectively, i understand 24 is just for the counter...

i will look into getting some caps, i have never changed caps before...is it best to snip off the old ones and solder to their legs or remove them properly?

cheers
 
its a pp-7b, pin 9 on the 9p reads 11.8v, pins 4 and 5 are 10.45v...according to the manual they should be 24v and 12v respectively, i understand 24 is just for the counter...

i will look into getting some caps, i have never changed caps before...is it best to snip off the old ones and solder to their legs or remove them properly?

cheers

Desolder them, and then replace them. Do one at a time to make sure you get the right ones in the right spots.

Make sure the polarization is correct on them as well. Putting a Cap in backwards could cause the cap to explode.
 
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