Philips 50IC36 No FM - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Nuvistor · 21st May 2018, 9:54 pm

If the local osc is working you could still get beats but you will be able to tell with the frequency in use.

If you have a SG you could also feed a 10.7Mhz signal into the IF strip to check if that is working, it’s another test.

I will feel bad if after this it is the IC but I always think testing is better than just guessing.

davidgem1406 · 23rd May 2018, 2:01 pm

Hello all,

Thanks to all for your input and help. The problem is solved.
It was to do with the supply for the Varicap tuning. The circuit board is a small board separate too the main PCB.

I lifted the board so that I could get access to measure the voltages on the voltage converter circuit, TC428.
As I lifted the board the FM came to life, just for a moment. As I turned the board over a wire just fell away. This was the wire that goes from the adjustment pot R686 to feed the +4V to the tuning circuitry.
it could never have been making a good connection and must have been a very dry connection for a long time. It was soldered back and all FM channels were working.

Once again, thanks to all.
Regards Dave.

P.S. Frank, no need to feel bad, it wasn't.

Nuvistor · 23rd May 2018, 2:05 pm

Excellent news, well done.

Nuvistor · 23rd May 2018, 2:51 pm

If it’s not all boxed up it would be interesting and educational to see what your scope shows on the tests you did earlier.

21st May 2018, 9:54 pm	#21
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Philips 50IC36 No FM If the local osc is working you could still get beats but you will be able to tell with the frequency in use. If you have a SG you could also feed a 10.7Mhz signal into the IF strip to check if that is working, it’s another test. I will feel bad if after this it is the IC but I always think testing is better than just guessing. __________________ Frank

23rd May 2018, 2:01 pm	#22
davidgem1406 Heptode Join Date: Feb 2011 Location: Sheerness, Kent, UK. Posts: 936	Re: Philips 50IC36 No FM Hello all, Thanks to all for your input and help. The problem is solved. It was to do with the supply for the Varicap tuning. The circuit board is a small board separate too the main PCB. I lifted the board so that I could get access to measure the voltages on the voltage converter circuit, TC428. As I lifted the board the FM came to life, just for a moment. As I turned the board over a wire just fell away. This was the wire that goes from the adjustment pot R686 to feed the +4V to the tuning circuitry. it could never have been making a good connection and must have been a very dry connection for a long time. It was soldered back and all FM channels were working. Once again, thanks to all. Regards Dave. P.S. Frank, no need to feel bad, it wasn't.

23rd May 2018, 2:05 pm	#23
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Philips 50IC36 No FM Excellent news, well done. __________________ Frank

23rd May 2018, 2:51 pm	#24
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Philips 50IC36 No FM If it’s not all boxed up it would be interesting and educational to see what your scope shows on the tests you did earlier. __________________ Frank