Killed DK Jr. Machine by bypassing Monitor Isolation Transformer

john2654

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Killed DK Jr. Machine by bypassing Monitor Isolation Transformer

OK, I had a problem with my Donkey Kong Jr. Somehow I ended up unplugging the internal cord that goes straight to the monitor chassis and plugged it into a wall outlet. It blew the 4 Amp fuse on the monitor chassis, replaced it, put the power cord back on the Isolation Transformer, but it does not power up anymore. The monitor nor the DK jr. board power up. Only thing that works still is the marquee light. How did I kill all that stuff? What should I check? (The reason I bypassed the Isolation Transformer was because I thought it was inline. The plug looked like it was just in a standard 2 socket AC splitter, so I didn't think I was bypassing it) UGHHHHHH!!!
 
Well, you won't get sound if the monitor isn't working, so you probably won't know for sure if the game pcb is working or not. You could check the fuses in the bottom of the cab if the outlet in the bottom doesn't measure 100vac.

If you plugged a 100v Nintendo monitor that needs isolation directly into a 120v wall outlet, then you most likely blew some of the rectifying diodes in the power section, and maybe the voltage regulator....
 
I'm not positive about the DK setup, but I fried both the monitor AND the board in a Killer Instinct like this. The monitor is isolated from earth ground... so if you bypass that, you just plugged a/c into ground. What it did on my killer instinct is it sent ac down the VIDEO ground line, and literally burnt up the top part of the board where that pin went in through the jamma harness. I had to pay Chad at arcadecup to repair it all for me, he's the man by the way.

So yeah it's POSSIBLE that you fried the board too... but like said above it's hard to tell on a Nintendo because of the amp on the monitor board.
 
Replaced the big resistor...R609....20W180ohms with no change, still dead. What else should I try to replace? What are the values of the rectifier diodes D601, D602, D603, D604? I heard 3 Amps and I tried looking up the part # and it says 1.2 Amps.
 
I heard 3 Amps and I tried looking up the part # and it says 1.2 Amps.

I forget what's actually in there, they might be 1.5A, I think the last time I replaced them I used 3A diodes... doesn't really matter. Look up the part number on the 'net to figure out what those are, and use something rated the same or higher. You can get them at Radio Shack. But if you plugged it straight into the wall, you almost certainally blew some of them. You can desolder them and check with your meter. They've probably become "reversable diodes" (i.e. shorted) now... :D

-Ian
 
What rectifier diodes do I need for D601, D602, D603, D604. Radio shack has some that are 3 amp 400 volts. Are these correct?
 
Tried replacing rectifier diodes D601, D602, D603, D604 & the big resistor...R609....20W180ohms with no change, still dead.

Gave up, anyone want a parts chassis...make an offer.
Comes with all wiring and the 3 boards and small audio transformer.
Will also include a Bob Roberts Cap Kit- might just have a blown cap, might fix it???
 
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