Toshiba RTS913 Radio crackling in stereo

S

Sabum

New Member
Hello,



I am currently restoring a Boombeat 40 and am having the problem that when listening to FM radio in stereo mode, there is a crackling sound at high frequencies. I have already replaced all the electrolytic capacitors and the ceramic capacitors responsible for the low-pass filter on the TA7323P IC, which is responsible for FM stereo reception.

This did not remedy the problem. I even replaced the IC itself with an identical model. Then the stereo sound disappeared completely. This means that the new (certainly used) IC could not handle the 19 kHz pilot tone. So I put the old one back in and the distortion is back, but only in stereo mode. There is no distortion in mono.

I'm slowly reaching the end of my tether. Could it be the FM/AM detector chip TA7614AP? Does anyone have any experience with this?

Thanks in advance and best regards,



Michael
 
S

Sabum

New Member
I was able to solve the problem myself.

A pot R203 needed to be readjusted. I had 83.9 kHz instead of 76.0 kHz running on pin 4 of the IC, which meant that the PLL circuit couldn't correctly reproduce the 19 kHz pilot tone in phase.

Now it's been readjusted and the crackling is gone...

Just for your information, in case anyone else has the same problem.
 
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