No Luck With Donkey Kong Jr. Sound

paulliadis

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Crap. I replaced the sound transformer on my Donkey Kong Junior tonight with a replacement from cwales hoping that would correct my sound problems. No luck. While I'm sure my sound transformer needed replaced, I still have issues.

Rather than the extremely loud hum type noise I was getting before (think of placing a microphone beside a speaker if you were in a band) now I'm getting a loud bong or dong sound. This is with the sound turned way down. I dare not even try it with the sound pot turned up because I'll wake my kids. I'll try that tomorrow and see what happens.

A bummer for sure. Seems to me I'm looking at either a cap kit for the sound amp or trying to find a replacement amp board (which I haven't been able to do yet).

Frustrating end to the day, for sure. At least I was able to play it a bit.

Paul
 
Welp, time to rebuild the sound board.....
Bob Roberts sells a nice rebuild kit....a few caps, and 2 transistors, easy to do, and that will almost certainly fix your problem....
 
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That little amp board is an ideal starter project actually.

Yeah it IS a good starter! The only issue I ever have is getting the 2 screws on the transistors/heat sinks off . Helps to have a small 90deg phillips head screw driver. Make sure to use a thermal paste when you reattach the new transistor to the heatsinks.......
 
Yeah it IS a good starter! The only issue I ever have is getting the 2 screws on the transistors/heat sinks off . Helps to have a small 90deg phillips head screw driver. Make sure to use a thermal paste when you reattach the new transistor to the heatsinks.......


Simply desolder the heatsink on one side and its easy to get to the screws. The amp board usually has one or two caps with legs rotted off and this is likely your problem.
 
Seems like I'll be asking some questions here. Didn't know I'd need any thermal paste. Figured I'd need to desolder, though. I don't suppose anybody has a step-by-step on doing a cap kit on one of these amps? I figure I can figure it out, but doesn't hurt to ask.

Paul
 
Verified that the sound works but is way too loud when the sound pot is in any position other than all the way down. I thought this but was able to test with the kids awake.
 
No, I replaced the sound transformer but didn't have an exact feel for what the audio sounded after that. I got that feel yesterday.

I have yet to install the cap kit from Bob Roberts. I'll be doing that in the next couple weeks (once I receive the kit).
 
All five of those pots are notorious for failing, Bob has them in a set for $10.

The pot does adjust the sound. It just starts from unbearably loud and goes to make small babies cry loud.

I'm gonna do the cap kit and if that doesn't work, then I'll replace the pots. Does this make sense, keeping in mind that my cap kit order just went in the mail? :)
 
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