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Old 22nd Jan 2009, 7:11 pm   #1
dsergeant
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Default Old Windsor radio

A chap brought in a very old radio yesterday for me to look at. It seem he inherited it and it has probably not been used for many years. The back is missing and the only identification is 'Windsor' on a label stuck to the very dirty dial glass.

A search through Paul's CDs and a Google search got me nowhere so I did a search on this forum and came across a thread at https://www.vintage-radio.net/forum/...ad.php?t=26554 Lo and behold the photos there proved that I have the exact same radio (not checked the valve types yet). It is quite dusty but the dial, what I can see of it, looks in good condition. I shall be digging deeper into it next week, but in the meantime did anybody find an circuits etc for them? Not sure though how much time it is worth spending on it.

Dave
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Old 22nd Jan 2009, 7:51 pm   #2
Paul_RK
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Default Re: Old Windsor radio

Afraid mine's just been gathering dust again. It's odd the way these, obscure as they are, seem to outnumber many readily identifiable models from major manufacturers: I've noticed some few examples down the years in photos at swapmeets etc. since acquiring my set.

Regards,
Paul
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Old 2nd Apr 2009, 2:02 pm   #3
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Default Re: Old Windsor radio

Well 'next week' turned out to be 3 months later but today I got round to looking at this oddball set again. I checked the electrolytics which seemed mostly OK, fitted a new mains cable, then found the on/off switch (part of volume control) was open circuit... so bypassed that. It powers up and the heaters light but that is about it - low but rising HT on the first section of the mains filter cap but only a few volts on the second section and no sign of anything coming out of the speaker.

Since circuits seem unavailable I think I shall have to ask the chap what he wants to do with it - freecycle or the next collection by www.weeecollect.it perhaps? Has anybody managed to get any further with these beasts, it does seem rather a shame just to scrap it.

Dave

Last edited by dsergeant; 2nd Apr 2009 at 2:03 pm. Reason: typo
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Old 2nd Apr 2009, 2:08 pm   #4
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Default Re: Old Windsor radio

What valves are in it and have you taken any pictures we can see. Has it got a Transformer or a Dropper Resistor. Mains filter cap across mains or elsewhere in the set?

If we haven't got a manual, we have to work without, don't we.

Cheers,

Steve P.
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Old 2nd Apr 2009, 2:11 pm   #5
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Default Re: Old Windsor radio

It appears to be a fairly standard circuit for the period, and they were far from complicated.
It should be possible to get further towards a working set without too much trouble.

As you didnt mention smoke, that (probably) rules out the likelyhood of a short on the HT line.
Many of the sets of the same era will be similar, so pick one that you have, or can get, the circuit for.
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Old 2nd Apr 2009, 2:14 pm   #6
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Default Re: Old Windsor radio

I agree, it seems a shame to scrap it.

This kind of fault shouldn't be too taxing for someone as experienced as you to sort out, even with no diagram.

Either something's loading the HT excessively, or maybe the rectifier's faulty.

Have you tried temporarily connecting modern electrolytics in place of the original reservoir/smoothing caps?

Does the audio OP transformer check-out OK with an ohmeter?

Nick.
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Old 2nd Apr 2009, 3:26 pm   #7
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Default Re: Old Windsor radio

Where's the fun in always having a schematic on hand ??
This one sounds all the more interesting for lack of data !
Sounds like the speaker field coil could be open ( if fitted ) or other smoothing component. ( is that a choke visible bottom right on the pic from the other thread ? )
You should have this up and running within the hour, albeit with a few temporary 'plasters' to fix the broken bits.

Andy
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Old 2nd Apr 2009, 4:22 pm   #8
Darren-UK
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Default Re: Old Windsor radio

Windsor was a brandname used by Taylor (of test equipment fame), so could this radio be from the same origin? Did Taylor make anything other than test gear?
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Old 2nd Apr 2009, 4:38 pm   #9
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Default Re: Old Windsor radio

I tend to agree with the other posters -- dive in and have a go!

Judging by the picture, it's a superhet (from the tuning capacitor) meant for AC mains (from the transformer with the voltage selector deeley on top). So that will be ..... triode-hexode frequency changer, pentode IF amp, double diode-triode detector/AF preamp, pentode AF power amp, full-wave rectifier. There are hundreds of similar receivers and once you've seen one, you've pretty much seen them all.

If there's no HT, try pulling out every valve except the rectifier and measuring again. If the speaker has an energised field coil, this will be part of the PSU smoothing network: test it for continuity. Is there AC on both anodes of the rectifier? Is it getting hot? (Sometimes, rectifiers have their own heater supply winding on the transformer.)

While the valves are out, check the speaker and its transformer for continuity, and replace the grid coupling capacitor on the audio amp.
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Old 2nd Apr 2009, 5:00 pm   #10
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Default Re: Old Windsor radio

OK chaps, I have just spent another 15 minutes looking at it. It is a pretty standard full wave rectifier supply from the transformer. I was a bit confused in that they have used all the NC pins of the UU6 rectifier as tag stips, but having traced that wiring that much is clear. If I disconnect the filter resistor between the two smoothing caps I get 400V on the cap, so that side is OK.

I then found the fault. There is around 300ohms from the filter side cap down to deck - this is an internal short in the audio output transformer (the small transformer you see on the photos)! So at least I now know what is loading the psu (that series filter R gets damned hot!). I will have to have a think as to whether it is worth trying to find a replacement transformer (not the sort of thing I have in my very modern junk box...).

Thanks chaps for the suggestions.

Dave
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Old 2nd Apr 2009, 5:05 pm   #11
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Default Re: Old Windsor radio

No problem. You can fit nearly any O/P transformer in place of this and it'll work.

Cheers,

Steve P.
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Old 7th Apr 2009, 4:43 pm   #12
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Default Re: Old Windsor radio

Many thanks to Alan Stepney who kindly sent me a suitable audio output transformer. I fitted it this afternoon and was greeted with the pleasant sound of stations. Initially it was only working on MW so out came the switch cleaner (my tin of Philips switch cleaner is nearly empty...) but in fact the problem was broken wires on three of the coils. Having repaired that it is now working fully on all bands - LW, MW, SW1 and SW2. Only tested with a bit of wire stuck in the socket, guess with a decent aerial it will be quite good.

New dial lights fitted so all I have to do now is to put the chassis back in the box and tidy it up. A good job done...

Dave
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Old 7th Apr 2009, 7:16 pm   #13
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Default Re: Old Windsor radio

Well done Dave, another interesting old radio saved

Have you changed the grid coupling cap (as AJS_Derby suggested above)? It would be a shame to damage the "new" transformer.

Nick.
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Old 8th Apr 2009, 2:36 pm   #14
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Default Re: Old Windsor radio

Attaboy Dave ! Knew you'd get it sorted ! Andy
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Old 8th Apr 2009, 5:46 pm   #15
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Default Re: Old Windsor radio

Just to be sure I did change the output valve grid coupling cap - a 10nF 1kV - even though the original measured OK. Now back in its case and working fine.

Thanks all for your help.

Dave
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