UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - My first foray into Old model TV repairs. Ferguson 991T.

AdrianH · 24th Sep 2020, 5:23 pm

Thanks for that Graham, Why I did not see the resistance values I do not know? A case of RTFM at this end.

I have basically just been spending time looking things over, checking a few resistances, the mains switch was bad, but has cleaned up with some solvent and contact cleaner, went from 90 Ohms to 0, so that is good.

I cut out the 0.1uF cap across the mains it was in an horrible state, looks like the wax coating had all soaked off the thing and solidified over the chassis and the bottom of the cap. So a couple of Panasonic X2 rated ones will bought for this.

I just placed two PY82 valves in the PL81 and PY81 valve positions to check out the heater continuity and all seems to be fine, the christmas tree dropper is giving me the correct values.

OK John on the tuning control, it is free to turn OK from 1 to 5 so that looks OK the ferrite formers are moving freely.

I did get confused over the fact the V2b cathode has a TV co-axial socket connected to it, but assume that would be from a tuner IF output.

I have an idea. I am still getting hold of the PL81 PY81 valves for the OPT stage so they will be several days to arrive. From what I have read many will bring up the sets on a variac leaving them at low settings for some hours to give capacitors chance to reform, before stepping up a bit etc.

So I was thinking of using one of my 12 Volt Buck power supplies and sticking it across the HT line and starting off at 50 Volts taking it slowly up over hours to 200 Volts. As the heaters are not on and I am missing the LOPT valves there should be no appreciable current draw, but it may give me a chance to check a bit more out before I finally start applying mains power.

Adrian

24th Sep 2020, 5:23 pm	#25
AdrianH Octode Join Date: Mar 2020 Location: Blackburn with Darwen, Lancashire, UK. Posts: 1,572	Re: My first foray into Old model TV repairs. Thanks for that Graham, Why I did not see the resistance values I do not know? A case of RTFM at this end. I have basically just been spending time looking things over, checking a few resistances, the mains switch was bad, but has cleaned up with some solvent and contact cleaner, went from 90 Ohms to 0, so that is good. I cut out the 0.1uF cap across the mains it was in an horrible state, looks like the wax coating had all soaked off the thing and solidified over the chassis and the bottom of the cap. So a couple of Panasonic X2 rated ones will bought for this. I just placed two PY82 valves in the PL81 and PY81 valve positions to check out the heater continuity and all seems to be fine, the christmas tree dropper is giving me the correct values. OK John on the tuning control, it is free to turn OK from 1 to 5 so that looks OK the ferrite formers are moving freely. I did get confused over the fact the V2b cathode has a TV co-axial socket connected to it, but assume that would be from a tuner IF output. I have an idea. I am still getting hold of the PL81 PY81 valves for the OPT stage so they will be several days to arrive. From what I have read many will bring up the sets on a variac leaving them at low settings for some hours to give capacitors chance to reform, before stepping up a bit etc. So I was thinking of using one of my 12 Volt Buck power supplies and sticking it across the HT line and starting off at 50 Volts taking it slowly up over hours to 200 Volts. As the heaters are not on and I am missing the LOPT valves there should be no appreciable current draw, but it may give me a chance to check a bit more out before I finally start applying mains power. Adrian __________________ Asking questions and learning, or trying to! Youtube EF91Valve