Re: Need to fix old valve radio


"Radiosrfun" <Radiosrfun@xxxxxxxxxxxxxx> wrote in message news:45ed6b96$0$6824$ecde5a14@xxxxxxxxxxxxxxxxxxx
<lafayetteradio@xxxxxxxxxxxxxx> wrote in message news:1173185992.671696.121470@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 4 Mar, 23:28, lafayettera...@xxxxxxxxxxxxxx wrote:
...and lastly, the radio has not been used since the last time I
tested
it about 10 years ago. Then it worked fine, no I tested it again and
suddenly there is this problem. It is entirely possible that it was
knocked (I hope not dropped) while in storage, but there is nothing
visibly broken, and all the valves do glow.
BTW, I tried removing the valves one by one and seeing if one valve
did not "make a difference", but this approach did not work, any valve
removed results in no sound at all.

Schematic now available, at
http://www.geocities.com/lafayetteradio1@xxxxxxxxxxxxxx

I looked at some of the pictures. My guess is that you basically need to measure every resistor and capacitor in this set. You most likely have several resistors that have gone WAY up in value and several capacitors with excessive leakage resistance. Do not be surprised if you have to replace every one of those wax coated capacitors and many of the resistors as well. A usual suspect for your symptom is the resistor that feeds the plate of the audio amplifier (6SQ7) which should be in the 100K to 470K ohm range.

David

.

Relevant Pages

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    ... I tried removing the valves one by one and seeing if one valve ... You most likely have several resistors that have gone WAY up in value and several capacitors with excessive leakage resistance. ... Do not be surprised if you have to replace every one of those wax coated capacitors and many of the resistors as well. ... A usual suspect for your symptom is the resistor that feeds the plate of the audio amplifier which should be in the 100K to 470K ohm range. ...
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