UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

cathoderay57 · 25th Sep 2021, 2:41 pm

Sounds like shorting vanes on C6 tuning gang. Mind you, with C22 in series that would have to be s/c as well. Can you measure the actual anode voltage on V1a with the fault present? A useful check might be with power off and the SW.F2 switch insulated to measure the resistance between V1a anode feed supply and chassis. Then work your way down the anode feed resistor chain. There's always the possibility of a solder blob or stray wire shorting the anode pin to chassis. The other area to look at is that for some reason there only seems to be a grid 2 feed to V4 on FM so check if V4 is drawing excessive grid 2 current on FM. Jerry

25th Sep 2021, 2:41 pm	#3
cathoderay57 Nonode Join Date: Oct 2017 Location: Bristol, UK. Posts: 2,386	Re: Philips 543A Low HT on FM Sounds like shorting vanes on C6 tuning gang. Mind you, with C22 in series that would have to be s/c as well. Can you measure the actual anode voltage on V1a with the fault present? A useful check might be with power off and the SW.F2 switch insulated to measure the resistance between V1a anode feed supply and chassis. Then work your way down the anode feed resistor chain. There's always the possibility of a solder blob or stray wire shorting the anode pin to chassis. The other area to look at is that for some reason there only seems to be a grid 2 feed to V4 on FM so check if V4 is drawing excessive grid 2 current on FM. Jerry Last edited by cathoderay57; 25th Sep 2021 at 3:10 pm.