Murphy U502 voltage readings

[colebrooker]

I think this fault may date back a good few years. It is only recently that I have been tackling it. There are still some wax capacitors left in, would it be worth replacing these?
David

[Nuvistor]

Originally Posted by colebrooker

There are still some wax capacitors left in, would it be worth replacing these?

Probably but which are they?

Frank

[ukcol]

Originally Posted by colebrooker

Now I have replaced the Hunts.......

Originally Posted by colebrooker

There are still some wax capacitors left in.....

Replace all the paper capacitors David; I think we had all assumed that from your first post.

These are the ones to change if you haven't already done so:

C44 0.01uF This component won't be responsible for your symptom but it must be changed to avoid damage to the output stage.

C21 0.003uF

C24 0.01uF

C25 0.01uF

C28 0.003uF

C31 0.01uF

C37 0.01uF

C42 0.01uF

C46 0.02uF

Check the component list in the service data and use capacitors of the same or higher working voltage for replacements.

Check all your work and make sure you haven't made any wiring errors.


C22 and C29 (both 1800pF) are also vital to the stability of the I.F. amplifier but they are ceramic types and unlikely to be faulty; only investigate them if you still have the symptom after changing the paper capacitors.

[colebrooker]

Colin, thanks for the list. Yes I still have some to do and it's going to take a while.
Regards, David

[ukcol]

Good luck.

[colebrooker]

Well, all capacitors on the list now replaced and it's a success. The little Murphy VHF set is now back together and working. Thanks for the help I have received. This has been my first vintage set recovery. The next one is a Marconiphone.
David.