Besides replacing all the electrolytic capacitors, two revisions were done on this radio. A heat sink was added to the audio chip, and my usual Din to 4 pin mic jack conversion. Initially the audio IC (uPC1224H) was fried. Fortunately I found another one in my audio IC bin. I believe it was scavenged from a few stereo boom boxes that I did in the past. The new chip sounded great, but it was getting too hot. That’s probably why the original IC was toast in the first place. There’s possible circuit mods that may have helped, but a simple added heat sink solved the overheating issue. The IC now remains lukewarm at high volume levels. Boom boxes and other amplifier applications that use this type of high power IC ordinarily provide an adequate heat sink.
I immediately noted a wider Rx audio response, more bass in particular. Along with my Bearcat external speaker it’s been my main listening pleasure for the past two weeks. I provided a data sheet for those that may want additional info on this IC.
The second photo shows the top side and circuit board pinout for the Din jack connections. Actually I cut off the protruding end of this board to make room for the new jack, but the piece was still used as a reference for mic wire attachments to other corresponding areas of the print.
I immediately noted a wider Rx audio response, more bass in particular. Along with my Bearcat external speaker it’s been my main listening pleasure for the past two weeks. I provided a data sheet for those that may want additional info on this IC.
The second photo shows the top side and circuit board pinout for the Din jack connections. Actually I cut off the protruding end of this board to make room for the new jack, but the piece was still used as a reference for mic wire attachments to other corresponding areas of the print.
