Plate Voltage on a Philco 37-650-6J5 tube - Printable Version

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+--- Thread: Plate Voltage on a Philco 37-650-6J5 tube (/showthread.php?tid=14227)

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Plate Voltage on a Philco 37-650-6J5 tube - onlyrick - 03-15-2016

Hello
I got my Philco 37-650 set up and running,with a lot of time spent on it,I
played it about seven times for about four hours at a time,worked fine
never stopping,I have changed all caps but not the mica caps and about 90% of
the resistors.It stopped playing two nights ago,made me sick,so much
time and effort spent on it,refinished the cabinet and installed new
grill cloth.When it stopped it made a low crackling sound and died,I
left it for a few days had to get away from it,today I started to check
the voltage on all tubes when I got to the 6J5 there was no plate voltage
and when I checked the service data sheet I have it had no voltage for the plate
on the 6J5,is this the way it is no voltage on the plate ?.A strange thing happened the
set started to play again while checking voltage on the 6J5 a little bit of low crackling noise but came to
life,I had given up just too much work and those black tub caps are no fun
at all.I checked the voltage on the 6J5 with the set playing but nothing
on the plate,now as I played it the crackling noise was still there on and
off,so I don,t play very long at all, a minute or two at most,I am afraid it
will quite again and never start ,I used a probe and moved every wire
and joint I could see with no effect,any ideas where I should look,I
would be very thankful for any help at all,all the best Rick

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RE: Plate Voltage on a Philco 37-650-6J5 tube - morzh - 03-15-2016

Try to clean the socket and possibly the tube or clean it's pins. It's a detector, not much voltage there. Rock it, tap on it with pencil....see if there is crackling, try to localize it.

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RE: Plate Voltage on a Philco 37-650-6J5 tube - onlyrick - 03-15-2016

Hello
Thanks for the reply,I did sand the pins and used a very small round file
on the tube base holes and used a tooth pick with some dioxit contact cleaner
on it,but will try again thanks so much Rick

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RE: Plate Voltage on a Philco 37-650-6J5 tube - Kenneth F. Besso Jr. - 03-16-2016

  Try another TUBE   ----6J7

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RE: Plate Voltage on a Philco 37-650-6J5 tube - John Bartley - 03-16-2016

Sometimes, not often, crackling sounds are made by resistors that are on the way out. I have seen this a couple of times in AA5's where the screen resistor on the audio output (50C5) fails and that crackling sound is a warning about that resistor about to fail.

Do you have a scope? If so, start at the speaker and work backwards until your scope shows a "crackle-free" signal. At that point you have just passed by the defective stage. Look for the defective part in that stage.

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RE: Plate Voltage on a Philco 37-650-6J5 tube - onlyrick - 03-16-2016

Hello John
I only have two more resistors left that have not been changed ,I don,t
have a scope so I think I will just go ahead and change them,thanks
for the tip,all the best Rick

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RE: Plate Voltage on a Philco 37-650-6J5 tube - onlyrick - 03-16-2016

Hello Kennith
Did you mean a 6K7 tube this set has no 6J7,if so I did try that,in fact
I tried every tube with another spare,thanks anyway,all the best Rick

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