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Old 1st Jul 2021, 10:02 pm   #41
nzoomed
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

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Originally Posted by joebog1 View Post
I don't know the brand of those caps, but if they are all the same manufacturer I would change 'em all. The ones in the pic look decidedly nasty and I'm not really sure, but they look like waxies of some form or other. In the radio section I suspect that many of them will be somewhat better quality and be silver mica or ceramic. "SOME" silver micas can get nasty too!! Australian made SM Simplex little square boxes especially, but I wouldn't expect to see them in that radio.

Maybe take a pic of the inside of the whole chassis and post it here.

Joe
Well, ive got some good news, ive been over analysing the whole thing and it turns out it was something simple!

It was just a dirty valve socket (the one of the EABC80) I did the usual tapping around the chassis and found that the sound would come and go, i then moved the valve opposite around and found it would come right.
So i removed the tube and sprayed some contact cleaner in the socket and its been fine ever since!
I was a bit worried that there was still some other fault (other than the "that' capacitors) that could have been the issue, and still potentially cause the newly wound OT to fail.

As far as these capacitros go, they appear to be an early polyester type, I may unwind one and dissolve all the pitch coating to see whats inside.

Before I do that, I have a mate with a leakage tester who can test them to see if they were indeed the cause of the OT failure.

Yes it will be a good idea to replace all the caps anyway, although if these test fine and turn out to be polyester, they are likely not an issue.

Paper caps on the other hand.....

I dont appear to see any silver mica caps in this set, they all appear to be tubular ceramic caps.

I will grab some photos for your reference anyway.

the radio seems to be working very well, just need to sort out those dammed dial cords now!

Quote:
Originally Posted by Nanozeugma View Post
First off, an excellent job rewinding the OPTX.
I have read through the thread in it's entirety, and you do not appear to say that you had the radio working at any point with the original OPTX before it failed (?)
Therefore it begs the question, had the original volume control been replaced at some point with an incorrect type? Have you removed it from cct and metered it against the specified value? It seems to be a tapped one which would be difficult to replace.
The capacitors you illustrate are well known Philips pitch encapsulated specimens and virtually guaranteed to be leaky. Such components do not normally go short, just turn into virtual resistors. I would certainly replace them all. Markings may be ambiguous, go by the cct values. The fact that the sound level "jumps" at a certain point on the volume control is suggestive of two possibilities, a damaged track or an incorrect replacement (linear for log law, for example.) Best of luck in your endeavours.


Yes sorry, I did have the radio working before the transformer failed, i had even started a thread some time back about it which you should be able to find under my profile, i had intended to add to that thread, but its since expired and has been locked.

basically the radio started loosing volume while it ran and i kept turning it up until no more sound could be heard. It turned out the OT had failed on me.

Anyway, its definitely got the original tapped philips double gang pot which would be an impossible part to find a replacement for.

You likely have already read above what the issue was, but as you say, its still a good idea to replace all the caps.

Im unsure if the dirty contacts on that tube socket could have played a part in higher current draw happening on the OT primary or not.

Last edited by nzoomed; 1st Jul 2021 at 10:09 pm.
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Old 3rd Jul 2021, 5:07 pm   #42
Richardgr
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

The failure of the OT was more than likely the sympton of another problem, and replacing all the caps (except ceramic, mica and polyester) will eliminate a lot of uncertainty in the fault finding, and will reward you with a better sounding and more reliable radio. It's about the same bother to measure them for leakage as it is to swap them out.

I've replaced caps a few times, and lessons hard learnt are to use axial caps, and fit them so the values are easily readable afterwards.
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Old 3rd Jul 2021, 10:03 pm   #43
nzoomed
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

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Originally Posted by Richardgr View Post
The failure of the OT was more than likely the sympton of another problem, and replacing all the caps (except ceramic, mica and polyester) will eliminate a lot of uncertainty in the fault finding, and will reward you with a better sounding and more reliable radio. It's about the same bother to measure them for leakage as it is to swap them out.

I've replaced caps a few times, and lessons hard learnt are to use axial caps, and fit them so the values are easily readable afterwards.
Well the radio definitely sounds better than before without a doubt.
I typically just get standard high voltage polyester caps from my hobby store.
The axial type are a bit harder to get and have to buy those from the likes of RS.
Those yellow mallory ones are usually quite suitable, i have quite a good stock of mustard caps here too
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Old 5th Jul 2021, 9:52 pm   #44
AmadeusMozart
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

Great job on the OPT. Make sure to test new capacitors - recently had a new one that was shorted out of the box.

AM
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Old 6th Jul 2021, 6:05 am   #45
nzoomed
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

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Originally Posted by AmadeusMozart View Post
Great job on the OPT. Make sure to test new capacitors - recently had a new one that was shorted out of the box.

AM
Yes sure thing! I may end up keeping this radio since its working so well now.
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