PYE 15A volume
 

Hi there many thanks for your help on my valve question. I have replaced the AZ31 and the EBL31 valves and also the 0.1uf wax cap on the top of the chassis. My problem now is this I can tune in a sports program on MW but volume only kicks in when the pot is about 3/4 volume and at max you can only just hear it I have sprayed the vol control but no different. Can any one out there help this newby. Best regards Ron H.

Re: PYE 15A volume
 

Ron,
Need a bit more information here please.
If you tune away from the programme into the 'noise' between stations, do you get anything in the speaker at a lower volume setting? Or do you have to have the volume at 3/4 before you get any sound from the set?

Edit: Try touching the top socket marked 'PU', with no station tuned in - you should get a buzz from the speaker that gets louder as you increase the volume.

Alan

Re: PYE 15A volume
 

Have you checked the resistance of the potentiometer, should be around 470k test meter on resistance 2m with probe on wiper and one end of the pot it should vary 0 -470k if all OK, I would be looking at replacing all of the wax capacitors as this radio is 73 years old they will be pretty well be past there sale by date.
John

Re: PYE 15A volume
 

This set has a slightly more complicated than usual output stage due to the tone control.

Has the capacitor c22 on trader sheet been changed ?

If not there is a path if it's leaking to put + the on the grid.

Try changing the tone control see if it has any affect.

There are a few capacitors around the output stage that would be prime candidates for replacement.

Cheers

Mike T

Re: PYE 15A volume
 

Hi Ron, if you haven't got it already then I strongly recommend you purchase the Trader Sheet here https://www.service-data.com/product...42/6409/t15342 There are 2 other service sheets available for this radio but more people have access to the Trader Sheets than the others so it helps if we all have a common numbering system reference when identifying the components. The best start for diagnosis of your fault is to measure the anode and screen (grid 2) voltages and compare with those on the Trader Sheet. Often that will give a clue where the fault lies. Good luck, Cheers, Jerry

Re: PYE 15A volume
 

many thanks for your replies chaps I have put wire to the pu socket but all I get is a scratching sound no hum i have I will try the resistance check suggested by Johnny thanks for the diagrams I need these as I am new to this hobby. Best regards Ron h.

Re: PYE 15A volume
 

We were all new to it at one time!

Lets go back a step.
Have you plugged at least a 6 or 10 foot length of wire into the Aerial socket?
Do you get any other stations on MW and do you get stations on the other 2 bands?

Re: PYE 15A volume
 

These sets are short superhets so do typically need the volume control at a higher position than a standard 4 valve superhet. A lot will depend on the signal strength and aerial arrangements.

Re: PYE 15A volume
 

OK i have changed 7 caps no difference extended the Ariel no difference only getting interference on LW and SW Meter readings on pot two outer lugs 0 on wiper to outer lug 60ish but bouncing all over on rotation. Best regards Ron H.

Re: PYE 15A volume
 

Still have to replace C19 (on order).

Re: PYE 15A volume
 

errrgh, very possibly more than one fault then.
You should be receiving Radio 4 on long wave and lots of stations on short wave, even in the day time.

Using the Trader Sheet numbers, can you tell us which capacitors you have changed?

Then do some voltage checks on each valve in turn.
V1 the ECH35. Measure the voltages on pin 3 (anode h), pin 4 (grids 2/4) and pin 6 (anode t).
V2 EF39. Pin 3 (anode) and pin 4 (grid 2).
V3 EBL31. Pin 3 (anode), pin 6 (screen grid) and pin 8 (cathode).

Remember you are counting clockwise from under the chassis as described before. Clip the negative lead to the chassis and take care, you will have up to 300 volts HT on the anodes.

Alan.

Re: PYE 15A volume
 

Thanks for your Help Alan the caps I have replaced are 6-7-12-21-22-23 and the one fixed to chassis next to PU sockets can't see a number on my service sheet. I have ordered the C19 25 uf and will change that when it arrives. Hopefully I can get back to it tomorrow and do the checks on the valves once again thank you for the time trouble and patience. Best regards Ron H.

Re: PYE 15A volume
 

I would replace the audio grid coupling capacitor (C20) as well if you haven't already done so.

Lawrence.

Re: PYE 15A volume
 

Thanks Lawrence will do.

Re: PYE 15A volume
 

We've been here before. I'll see if I can get one of mine from the loft.

The voltages Alan suggests are important. I don't have the trader sheet but if you post the values I am sure someone will let you know if they are OK.

Another simple fault on these sets is not an easy one to repair though! Tune in a station, turn the set upside down and give it a shake or tap on the two round I.F. transformers. If the volume increases the slugs inside the transformers are broken.

Re: PYE 15A volume
 

Check these resistors. The values aren't too critical, 20% is OK

Re: PYE 15A volume
 

Once again thank you all I have just been struck down with a stinker of a cold and the heating in my man cave is struggling with the temp so low so it may be a couple of days before I get back to it. Best regards Ron H.

Re: PYE 15A volume
 

With the set off, I have put a low impedance signal on the primary of the IF transformer and looked at the voltage on the secondary with an old scope. The resonant frequency will be low due to the capacitance of the scope leads.
Then put a signal on the secondary and look at the primary. The resonant frequency should be about the same. Do the same thing on the second IF transformer. Five minutes finding some crock clip leads is all that is necessary, no dismantling.

A bodge would be to connect a variable capacitor external to the can to bring the resonant frequency of the faulty circuit down to the correct value.

Re: PYE 15A volume
 

As See_Mos says these sets do have an inherent fault the ferrite slugs on the end of the brass threaded rods in the IF cans do come apart. Switch the set on upside down and give the cans a flick with your finger, you will soon see if this is the problem, I have stripped and repaired many of these in the past, bit tricky but do able.
John

Re: PYE 15A volume
 

I've encountered this problem with several McMichael sets. Side fitting slugs.
Vaseline (petrolium jelly) or very thin teflon in the hole and then superglue gell. Insert while wet so that the slug won't catch and break off.