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Philco 42-380 No sound
#1

This radio worked fine after recapping the electrolytics and replacing the 6X5.  Suddenly it got quiet, now no sound other than a very faint speaker hum.  The power transformer is cool, so I do not think there is any short.  Can someone assist me with how to take voltages on this?  I have a multimeter but never measured voltages.  Perhaps the transformer is not putting the voltage out?

Thanks for reading.
#2

You mention recapping the electrolytics, but did you replace the other capacitors and check for out-of-tolerance resistors?

Your location is not listed so I'm not sure if there is a local radio club that could help you out or not. I just hesitate to have someone who has never measured voltages poking around in a live radio chassis. I don't want your first experience using a meter to be your last! What schematic do you have? The one listed on Nostalgia Air is pretty hard to read:

http://www.nostalgiaair.org/PagesByModel...013533.pdf

John KK4ZLF
Lexington, KY
"illegitimis non carborundum"
#3

Hi davidff,
John has some good advice and all in the Phorum will need to have their town and state added by June 1 so please go to the "User CP" then "Edit Profile" and update the information.

If only the electrolytics were recapped, the wax/paper caps could easily have failed.
#4

I replaced most of the paper caps,  I believe only 2 were left which I should replace.  I did not do anything with the resistors, assuming they would only cause distortion, not an "open" situation.
#5

There is a clearer schematic on the audiophool site. Resistors do tend to drift to higher values but can also fail open.
#6

(05-19-2015, 10:52 AM)klondike98 Wrote:  There is a clearer schematic on the audiophool site.........

That is a much, much better schematic, but it requires DjView to open.  davidff, if needed I can convert it to PDF and e-mail you a copy.  With the better schematic you can pull the 6X5 and take some resistance measurements on your power transformer and also check your resistors.

John KK4ZLF
Lexington, KY
"illegitimis non carborundum"
#7

Quote:Elliot Ness wrote: pull the 6X5 and take some resistance measurements on your power transformer and also check your resistors

...that would be with the radio UNPLUGGED Icon_biggrin
#8

David

Do you have a tube tester?
There can be many reasons. Tubes - one of them. It is unlikely your transformer. This is not a typical way they quit (possible but rare).

Do what John suggested. Then test the tubes. Especially you need to test 6X5.

One thing I would suggest myself: (after you do what John said) as you said, the radio does not smoke and the transformer is cool. If this is the case you could try to measure the B+ as it is. Measure it across the 8uF (I think it is 20A cap, the one after the field coil), between its chassis and the positive terminal.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#9

I will do that measurement that you suggest. I re-tested and substituted all the tubes and replaced every bypass cap except one that is in the XX tube area where it is a very tight area to work. The radio makes no sound other than a very quiet hum that you can hear only if you put your ear up to the speaker. It was playing perfectly clear and loud before it just quit on me.
#10

David might I suggest going to Chuck's site for the best and clearest information on Philcos. I never start a Philco without Chuck's information package.
Jerry
http://www.philcorepairbench.com/schematics.htm

A friend in need is a pest!  Bill Slee ca 1970.




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