Harmon Kardon HK430


Hello gang,
I am lucky enough to have acquired a HK430 from a very nice former owner. The FM tuning is silent.
I have checked the 3a 250v fuses(all good). 3 fuses on the back panel and 2 inside, I for each board.  I have used deoxit on the selector and or muting dials/buttons. I have made sure the speaker selector and muting switches are in the proper position.
Still no sound. The signal strength meter is moving as I tune up and down the FM dial.
I am a believer in checking the easy stuff for repair first.
Hmmmmmm....still no sound.
Any advice or resources to suggest? 
martygto

Showing 2 responses by atmasphere

Its unlikely that this is an easy thing to fix at home. But any competent technician should be able to sort it out.

There is a lot of variance in demultiplexer designs (this is the circuit that decades the FM stereo signal from the mono) and some of them don't play if the stereo indicator won't light up. In this case, it is common for the demultiplexer chip to fail and kill both the audio and the stereo indicator.

In this receiver the demultiplex is handled by the BA1310 chip; it drives the stereo indicator. If there is audio on pin 2 of the chip, it is likely that has failed. But if there is no audio, then there are only a few parts that can be the culprit. So your technician at least has a place to start...

The good news is that parts to fix this are not expensive. You can easily find the IC on ebay.
Since the meter moves, this means the voltage regulator for the FM is OK, as well as the front end and IF section.

Does the stereo indicator light up?
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