VHF90's and me!

[AlanBeckett]

I can see that all of the valves are working.

Tiny Electrons hurling themselves across vast distances attracted to the Anode

Start at the Volume Control Wiper with your Signal Injector or finger.

Alan

[Bushbaby]

Ho Ho - thanks for the jape.

I've put the injector across the wiper and I have a tone through the speaker. Time to use the tracer but first I need to find the valve pin connections.

R

[Bushbaby]

ok further to my last email I've used the tracer on pin2 of valve 4 (UF89) - no signal on mw or vhf. On pin 2 of valve 3(UF89) there is no signal on mw but there is a weak signal on vhf.

Any suggestions at this stage?

Thanks

Rob

[pwdrive]

Have you checked all the wave change switch contacts and the valve voltages Rob?

Lawrence.

[Bushbaby]

Lawrence,
I have just been doing this. I have trying to read the voltages for V3 and in touching pin 5 the radio burst into life on both mw and vhf. Its very clear and has a very good signal even in my garage (which is not the greatest for picking up stations). does this suggest a dry/dirty joint?

All working save that I need a red dial glass.

Regards

Rob

[pwdrive]

Lawrence,
I have just been doing this. I have trying to read the voltages for V3 and in touching pin 5 the radio burst into life on both mw and vhf. Its very clear and has a very good signal even in my garage (which is not the greatest for picking up stations). does this suggest a dry/dirty joint?

All working save that I need a red dial glass.

Regards

Rob

Rob, pin 5 is a heater connection and would not affect the signal if the heaters were previously lit up.
It could the coincidence of mechanical pressure when applying your meter probe to the valve base, with the set switched on give V3 and the other valves a quick wiggle, any cutting out or noise would normally indicate dirty valve pins or valve holder sockets if there are no dry soldered joints.
If the valve pins/sockets are ok then have a tap around with a plastic knitting needle for dry joints/loose connections, poor wave change switch contacts etc.

Lawrence.

[Refugee]

It sounds like a bad valve socket pin.
You can often rob an unused pin from another holder in the set to fix it.
With the set unplugged take the valve out and carefully touch each contact in the valve holder with a cocktail stick and if the ends of the contact move separately the contact is bad and will not make good connect with the valve pin.

[Bushbaby]

Hi all,
Yes I'm still here and after a very long absence I have returned to my white VHF90. I put the chassis in the case etc etc., switched on and........just hum. Thats all I'm getting on VHF and MW. I'm really cross now as its been working well out of the case. I can only think that it must be a poor connection somewhere. Any thoughts?

Thanks as always

Rob

[Bushbaby]

Hi All,
I tried to reproduce what in the steps I did before with pin 5 of valve 3. it crackled and started to work yet again. On closer inspection I found this.
   
Regards

Rob

[pwdrive]

Not doing a lot is it Rob.

Lawrence.