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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 24th Apr 2017, 1:57 pm   #1
telstar
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Default Philips 543A - no F.M

Hi. Just a tip for people that have this radio and are experiencing no F.M symptoms. The ECC85 is not always to blame. In my radio a simple cause, the connecting wire that links the first F.M I.F transformer to the ECH81 proved to be faulty (an internal break in the conductor wire). It may have been a bad batch - all bands now work.
Though that this small observation may help!
Cheers
Mike
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Old 24th Apr 2017, 6:20 pm   #2
vinrads
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Default Re: Philips 543A - no F.M

Nice one Mike , thank's Mick.
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Old 25th Apr 2017, 11:40 am   #3
telstar
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Default Re: Philips 543A - no F.M

Hi Mick. Glad that you appreciate the tip. The wire did not seem to be visually damaged, but by handling the insulation, there were noises of activity on F.M which then returned to normality. It now has excellent reception. Not the obvious thing to look for in radio repairs, but these little things are sometimes the key to repairing these radios. Previously, when touching the oscillator grid with a probe, I noticed that weak tuneable signals were heard in the speaker, so I decided to investigate further. I then replaced the offending wire.
Now, I have the unenviable job of re-stringing the ferrite antenna drive cord on the long and medium wave bands!
Cheers
Mike
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Old 1st May 2017, 12:25 pm   #4
Maarten
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Default Re: Philips 543A - no F.M

Another tip for no FM or partially no FM, is to check the anode resistors for the ECC85. If one or both have gone up, a fresh ECC85 might even get the FM to work again fo a while but at low anode voltage the emission of the valve needs to be really strong to do anything.
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Old 1st May 2017, 7:41 pm   #5
G6Tanuki
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Default Re: Philips 543A - no F.M

Check that the FM local-oscillator is actually oscillating: you can easily use a 'scanner' receiver to do this - listen 10.7MHz away from whatever frequency your radio's tuned to.

[Don't know about this particular set but some FM radios run the local-oscillator 10.7MHz above the reception-frequency, and others 10.7MHz below]

If the LO isn't oscillating then you'll hear very little - perhaps just a bit of shortwave-band breakthrough into the IF stages.
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Old 3rd May 2017, 2:57 pm   #6
telstar
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Default Re: Philips 543A - no F.M

The resistors in the Philips 543A f.m tuner were well in tolerance (thank goodness!). My radio is the moulded cabinet type made for the U.K market and not the 543A "Jupiter" (although I have both models).
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