Pye P224: Advice Please.

[Joe]

Thanks, Rob. I'll check it tomorrow, or rather later as it now is.

[Joe]

OK, this is getting weird.

I couldn't sleep and tested C45 around 0230 and found it does leak a bit, about 12uA at 15V.

This morning I put my AVO on pin 2 of the EL84 as per Rob T's suggestion and all seemed well as the voltage started at -7 and slowly fell to -14. The odd thing was that the radio was performing much better.

I disconnected the AVO and it sounded lousy but picked up as soon as it was reconnected. I tried my digital multimeter and that had the same effect.

I'll get these caps changed as they seem iffy whatever but some sort of explanation, suitable for a bear of very little brain, would be appreciated.

Cheers
Joe

[tiv48]

could be r20 (680k) gone high in value, or open circuit putting a meater pin 2 controle grid to earth alteres grid baising set in part by r20
rob t

[Joe]

You're a wise man, Rob T.

That resistor was up to 850K so I changed that for one I got out a 'bin in a college laboratory twenty-five years since. While I was in the area I also did R22

It now sounds better and connecting a meter doesn't make much odds. However, there's now about seven volts positive on pin 2 of the EL84. I'll leave it now until I get my new capacitors. I've also found another Hunt's thing lurking in an awkward place.

This job was supposed to be a simple confidence builder but I'm learning and am definitely enjoying myself: "The appetite soon sickens of the fruits of any form of self indulgence unless they come as a reward for hard labour and difficulties overcome."

[tiv48]

only thing left is c43 0.01mf its in the feed back loop along with r19 100k
see attached thum nail
rob t

[Joe]

Thanks for that, Rob. C43 is already on my Chop list as it a Hunt's. The resistor seems OK as it's reading 98 while in still in circuit.

I haven't done anything else to it today as I've been working outside while the weather allows. Playing with my chain-saw makes a change and if the wireless doesn't behave itself I'll bring it in and wave it about in a meaningful way and scare it into cooperating.

Cheers

- Joe

[Joe]

Measuring it in the circuit may give an artificially LOW reading if there's something else across it but this is certainly "Close enough for rock 'n' roll." To be truthful I'm loath to do more de-soldering than I have to as it's a PCB not a proper chassis and I don't want the tracks lifting.

I've had it on for the last hour and it's sounding great blasting Classic Rock out on Absolute Radio. I've got some new capacitors on order but temporarily tacked a replacement for C43 in place, it's legs aren't long enough to fit it properly. There's still a stubborn 6V on pin 2 of the EL84 which will hopefully clear off when the other bits have been done.

The background hum also seems to have gone, and it's running on it's original smoothing cans (could they have been reformed by use?) so I'm very happy all told.

Thanks for all the help so far.

- Joe

[Joe]

I've been playing this radio a lot in recent days and it's sounded terrific despite still having 9V on pin 2 of the EL84.

I got the final parts I wanted for it on today's post and got them fitted. This means that C31, C39, C43, C44, C45, C46, C49, R20 and R22 have been re-newed (R19 was bang on so hasn't been). That stray DC is still there but I wasn't bothered as it was working well beyond my satisfaction so I put it back together properly.

[attachment=790]

When I switched it back on it sounded blinking awful, worse than at any time since I started work on it. It sounded more like something vibrating so out came the chassis again but I couldn't see anything and it still sounded lousy.

I then spent an hour or so checking that nothing was shorting and that there were no dry joints.

I still thought it sounded more mechanical than electrical so tried another speaker and it played fine through that. The original sounds ropey when connected to a tranny so what's gone wrong with that I don't know. While working on the set I had a long lead connected to it and all I did today was solder the original wires back. I've never damaged a speaker before by soldering and would like to know just what I have done so I don't do it again.

I'd also like to thank everybody for their help, especially those who have gone above and beyond the call of duty. It would be invidious to name names but you know who you are.

All the best
Joe

[tiv48]

this does not look right the brackets seam to to be touching the loud speaker cone
try pulling the chassis out 1/2 an inchthe noise you hear is eith the voice coil rubbing on the magnet or the cone pushed forward
rob t

[tiv48]

look at the bend in the circuit board its not correct but i cant see how it should be fitted the brackets should shorly rest on the front board not on the speaker?
rob t