Pye P224: Advice Please.

[Steve_P]

Are you sure of the readings. Difference between Pin 2 and Pin 3, 7 Volts. Go across the two, 2 Volts!

This set has feedback - One side of the secondary and speaker is connected to earth. The other side is connected back into the circuit. Disconnect this and see if it helps. Lift R23.

It could be the speaker. Have you tried the bog roll trick? It may be damaged or off centre.

Of course it could be the valve. A tip - this valve is also used in domestic tape recorders, such as the Fidelity Playmaster. These are often got for next to nowt!

Have you checked C49?

Cheers,

Steve P.

[Joe]

Thanks, Steve; I'm starting to feel like cracking myself one with the EHT.

I've re-done those readings with both my AVO and DMM with the following results:

Pin 2 to earth = 6.5v (6.49v)
Pin 3 to earth = 12.5v (12.42v)
Pin 3 to 2 = 2.2v (1.72v)

Disconnecting R23 didn't make much odds, it may have reduced the overall volume a bit but that was all.

I'd already replaced C49 but took it out and tested it and that was OK.

The main problem today has been a loud constant hum which is there no matter what the volume is set to or whether it's on a wave-length or Gram. There was also some distortion but it didn't sound mechanical. However, I've got a spare 3 ohm speaker so tried it with that and it was fine. There's still a background hum but nothing like as bad and no circuit, old or new, is totally silent. The voltages quoted above were the same. Sadly this speaker is a round ten inch one so can't be used as a simple replacement. I'm really not sure what's up with the original as the cone doesn't feel scrunchy and it sounded fine this morning with a transistor playing through it out of the case.

I've got a Grundig reel-to-reel tape recorder in the loft so I'll have a look what valves that's got in it.

If it doesn't behave itself I'll have to start looking up trans-Pennine train services!

Thanks for your help.

All the best
Joe

[tiv48]

try shorting pin 2 to earth if the hum is still there susect smoothing ie a broken track im loathed to suspect the valve could be a heater cathode short but not often intermitent if hum goes its back to checking around the el84

[Joe]

Pin 2 to deck equals stony silence so that's a clue for tomorrow.

While investigating Steve P's idea earlier I found two more Hunt's capacitors. I changed C50 but have left C42 alone as it's 0.04uF and I don't know if it would be best replaced with a 0.033 or a 0.047 as it's bang in the middle.

I had the radio playing for over an hour earlier and it sounded fine. The voltages didn't alter to any notable degree either.

[Steve_P]

0.047 should be fine.

Deck is a term for Earth or Chassis.

Cheers,

Steve P.

[Joe]

Thanks, Steve.

I meant that connecting pin 2 of the EL82 to the chassis, which is connected to mains earth, resulted in silence, no hum or anything.

[tiv48]

still pionts to c43 unfortunetly i only have issue 2 of the circuit there is a difference in the feedback system
rob t

[Joe]

I've now changed C42 as well and, despite the old one leaking like the proverbial sieve, it's made no difference either to the sound or the cock-eyed voltages on the valve.

I've looked at the Grundig tape recorder but that uses an ECL86. It's a TK140 if anybody is interested.

I've now tried three different capacitors in position C43.

I'm leaving it alone now as I'm in danger of loosing my rag with it. It's looking like I'll have to put my hand in my pocket for professional attention.

Any ideas are still welcome.

Thanks all
- Joe

[Joe]

I don't know if this means anything but I've just tried sticking the LT supply through a rectifier with a 2200 uF capacitor on and it greatly reduced, but didn't completely kill, the hum.

I only ran it for a few seconds but would there be any harm in fitting this permanently?

- Joe

[Joe]

This is all very interesting but what about my rectifier (Post 67)?

There's no immediate rush for this info as I'm now going to get my dinner and make a rhubarb crumble.

- Joe