Break out the Simple Green!

I finally managed to trade off the Operation Thunderbolt for a Donkey Kong Jr. This game has been on my short list for a long time. I had seen several for sale, but this was the first non-working one to hit Craig's list. I traded the "100% working" Opt. Thunderbolt for this rather nice, but not working machine, in the hopes of doing a few repairs and cleaning it up. A good working Donkey Kong Jr. is worth about 3 times more than the game I traded, so if I can get it working and looking good, it will have been a pretty sweet deal.

Overall the cabinet is in fair to good condition. Mostly, the usual 28 years of grime, and scrapes and bruises. A half bottle of Simple Green and a ton of paper towels and it's looking even better. The bezel has a few scratches that I plan to buff, and I will need to replace the t-molding and instruction card. Also this machine is lacking a proper back door, which is a serious health hazard should anyone go sticking their little hands back there while the game is running. "Zapp!!!".

There are basically two major problems with this game. The first problem, no sound. The sound effects are one of the best things about the early Nintendo games. So, that will need to be resolved. The second issue is, and it's a big one, after about 3 minutes the screen goes to garbage. That looks to be a potentiometer issue.

The previous owner, thanks again Scott, mentioned that he had done a cap replacement on the Sanyo monitor, but that he was tired of fooling with it, and believed that the problem was somewhere in the monitor adjustment potentiometers.

I adjusted the pots (potentiometers) on the monitor and they seemed fine, it turned out to be a pair of pots located on the PCB. There were two located on the first PCB that controlled horizontal and vertical arrangement of the display. A quick look up on Bob Roberts site, and there they were, he sells them for a dollar a piece.

Next I checked into the sound issue. On Nintendo games, the amplifier for the sound is located on the chassis of the monitor. Bob Roberts also sells a rebuild kit for Nintendo sound boards, I think it was 7 dollars. I ordered that and went the extra mile and ordered the capacitor kit for the Sanyo EZ monitor. All total with shipping and the two pots mentioned earlier, came to 21 dollars.