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Old 24th Jun 2021, 7:35 am   #21
crackle
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

I am surprised you didn't buy one of the many OP transformers on Ebay.
Mike
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Old 25th Jun 2021, 2:19 am   #22
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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
Is there not a crimped on steel band around the whole transformer? The I's are normally held in place by that band.

These pictures show one of my transformers. Its a single ended line output transformer so very similar to what you need. The I's are placed into the top of the crimp band, the E's are placed into the band facing upwards. The whole thing is then crimped. When crimping on this band its essential not to grimp with pliers or similar, but a good quality vise with straight and parallel jaws will do the job OK. If you use pliers they will crimp only the edges of the steel band and will not press the whole thing together. That is guaranteed to cause lamination rattle. When doing this crimping dont be tempted to "squeeze the life out of it", just enough pressure to close down the steel band.

Hope this clarifies

Joe
I know what you are talking about, but this set doesnt mount the transformer in that way, take a look at the photos in post 2 for what it looks like.

Now im running into a spor of bother trying to find the right size bobbin.
The closest one i can find is labelled 3/4 which im assuming is the measurement in inches.

Only problem is these laminations are too tight to fit and there is also about a 3mm gap at the end which I dont know if that will be a problem.

Quote:
Originally Posted by crackle View Post
I am surprised you didn't buy one of the many OP transformers on Ebay.
Mike
Wrong spec for this set that requires the humbuck tap.
Either way, i want to try winding my first transformer with all this gear ive got!
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Old 25th Jun 2021, 5:23 am   #23
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

See - http://www.dissident-audio.com/Trans...ign_Manual.pdf for a good primer on the subject.

Insulating tape can be bought from here - https://brocott.co.uk/enamelled-copper-wire/ or you can use Kapton tape, available off Ebay, but it has a high dialectric value.

Andy.
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Old 25th Jun 2021, 9:56 am   #24
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

You can very easily make a new bobbin!!. That's not a hard part, a piece of red or black fibre like is used on car gaskets is cheap and plentiful. It's available in many thicknesses. If you manage to find some, before you cut it up, post your findings here and I am sure there will be many willing to show you the way.

For your little transformer I think something about .5mm to .75 mm thick will work fine. DONT use too thick a bobbin or you will run out of winding space, otherwise known as window. You will need some sort of winding machine, but an old fashioned "egg beater" hand drill served me well for years before I could afford a winding machine. You need to know EXACTLY the gear ratio of the drilling machine, that way you just count the handle turns, NOT the chuck revolutions.

The same fibre can be used for side cheeks for your first attempt at winding because it's the devils own work to wind a transformer without side cheeks. It also guarantees a very neat and most likely very good transformer for your first effort.

Joe
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Old 26th Jun 2021, 9:36 am   #25
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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
You can very easily make a new bobbin!!. That's not a hard part, a piece of red or black fibre like is used on car gaskets is cheap and plentiful. It's available in many thicknesses. If you manage to find some, before you cut it up, post your findings here and I am sure there will be many willing to show you the way.

For your little transformer I think something about .5mm to .75 mm thick will work fine. DONT use too thick a bobbin or you will run out of winding space, otherwise known as window. You will need some sort of winding machine, but an old fashioned "egg beater" hand drill served me well for years before I could afford a winding machine. You need to know EXACTLY the gear ratio of the drilling machine, that way you just count the handle turns, NOT the chuck revolutions.

The same fibre can be used for side cheeks for your first attempt at winding because it's the devils own work to wind a transformer without side cheeks. It also guarantees a very neat and most likely very good transformer for your first effort.

Joe
Well I have ended up looking at that option as it turns out.
I was going to make a simple cardboard bobbin like it originally had, but its hard to wind without side cheeks, but remembered ive just been given a 3D printer so just decided to draw something up and 3D print it!
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Old 27th Jun 2021, 3:31 am   #26
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

Looks VERY nice to me!!! I would suggest you don't print it with metal flake plastic filament though.
Tongue in cheek of course Joe
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Old 27th Jun 2021, 10:58 am   #27
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

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Looks VERY nice to me!!! I would suggest you don't print it with metal flake plastic filament though.
Tongue in cheek of course Joe
LOL definitely not the metal fibre type!
Its just basic PLA+ filament.

Here are some photos.
Winding it was a challenge, the wire kept twisting and getting very small kinks along the way.

Just got to lacquer it now, I've been told that nitrocellulose works well.
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Old 27th Jun 2021, 11:12 pm   #28
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

When I wind a transformer I put the roll of wire behind the bobbin, mounted on a piece of dowel so it unrolls. The wire should come from the top of the roll. I use my left hand to guide the wire onto the bobbin. You will need some sort of brake on the spool of wire to prevent it unrolling when you stop winding as the inertia will keep the spool spinning. It sounds complex, but it's a very simple way to do one offs without a proper winding machine. I think you understand what I'm talking about, but I can draw a few pics if you need better info.

Joe.
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Old 28th Jun 2021, 8:18 am   #29
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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
When I wind a transformer I put the roll of wire behind the bobbin, mounted on a piece of dowel so it unrolls. The wire should come from the top of the roll. I use my left hand to guide the wire onto the bobbin. You will need some sort of brake on the spool of wire to prevent it unrolling when you stop winding as the inertia will keep the spool spinning. It sounds complex, but it's a very simple way to do one offs without a proper winding machine. I think you understand what I'm talking about, but I can draw a few pics if you need better info.

Joe.
I had looked at doing it that way, but with the weight of the spool and the thinness of the wire, i thought doing that would snap, I know with the conical shaped spools it seems to be wound in such a way that its not a problem as it unwinds, as my other winding machine places the rolls into it in that manner with the wire being drawn from above.
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Old 28th Jun 2021, 9:39 am   #30
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

I only have tapered spools in larger guages, and they come in 30 KG when new. They do unwind from the top. Your 2nd pic shows I think a 500 gram roll. Its a bit of a knack to start slowely, so you dont break the wire, likewise, when you stop you slow down first and dont jerk to a stop.

I did state that after more than 50 years Im still learning to wind.
If you want to try something difficult, try winding a guitar pickup with 44 guage !!!.

Joe
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Old 28th Jun 2021, 11:04 pm   #31
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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 only have tapered spools in larger guages, and they come in 30 KG when new. They do unwind from the top. Your 2nd pic shows I think a 500 gram roll. Its a bit of a knack to start slowely, so you dont break the wire, likewise, when you stop you slow down first and dont jerk to a stop.

I did state that after more than 50 years Im still learning to wind.
If you want to try something difficult, try winding a guitar pickup with 44 guage !!!.

Joe
Yeah I think this is a 500 gram roll. I think with these types of rolls they have to unwind on the side while turning.

Ive got conical rolls that are pretty huge and easily weigh about 3-4KG or more.

I only set this basic unit up because it was the easiest to get to and everything is all stashed away until I get it all sorted out.

I think one of my other machines has a bar of some sort to slip the roll onto and tighten the tension to suit. But most of it looks like its set up to unspool from the conical rolls.

Ive got some heavy rolls with 2-3mm sized wire too, I expect you literally have to wind that stuff by hand. I doubt I will ever need to use those gauges unless im building some beefy high current power transformer.
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Old 29th Jun 2021, 11:56 am   #32
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

The bobbin looks superb.

Even fine copper wire is stronger than you might imagine, I have rewound a fair few headphones and intervalve transformers using the hand-drill and spool on a dowel method and never had a break.
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Old 29th Jun 2021, 10:58 pm   #33
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

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The bobbin looks superb.

Even fine copper wire is stronger than you might imagine, I have rewound a fair few headphones and intervalve transformers using the hand-drill and spool on a dowel method and never had a break.
Thats good to know.
I guess ive been taking it easy as ive never done this before.
I have one machine that has an automatic feeder and has these arms at the top with micro switches, im assuming its a safety cutoff that stops the machine if it jams?
This machine also would make a nicer job at winding, since it moves the bobbins side to side to wind evenly.
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Old 30th Jun 2021, 8:21 am   #34
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

Well Ive got some good news, the radio is working and sounding a million dollars now.
Ive got a new issue however, and thats that the volume control is not really working, I can only turn the volume down slightly, and not to zero, and the volume just jumps up real loud when you turn the volume up about 3/4 of the way.

Not sure if it has anything to do with it, but i did replace both of the "that" caps and another coupling cap that connects to the transformer
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Old 30th Jun 2021, 10:25 am   #35
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

Sounds like a "dead" volume pot!!.
Its most likely hard to replace if it also has the on/off switch.
BUT some pots are easy and cheap!!

cheers
Joe
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Old 30th Jun 2021, 11:38 am   #36
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

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Sounds like a "dead" volume pot!!.
Its most likely hard to replace if it also has the on/off switch.
BUT some pots are easy and cheap!!

cheers
Joe
I dont think its the pot, it was working perfect when the radio last was going.
something has changed since ive replaced the transformer and caps.

Could it be that the phasing is out on the negative feedback loop from the speaker?
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Old 30th Jun 2021, 10:48 pm   #37
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

Just reverse the two output wires and you will soon find out!!.

Joe
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Old 1st Jul 2021, 1:06 am   #38
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

Ive reversed the phasing on the OT secondary but its not made any difference.

Looks like some components values are different on this radio than whats specified on the radio.

Ive replaced caps C59, C60 ("that" capacitors 0.015uf) and C66

C66 is specified as 0.001uf but the cap i removed appears to be a higher value than that specified. I cant make out the code on the cap either as its not very readable

Ive attached a photo of the caps for reference, the 0.015uF cap is marked "15KP" and has 3.6 stamped on the bottom, but im not sure what the bottom code means.

however, the 0.001uF cap appears to be marked either 61KA or 51KA
That would quite likely make it much higher if thats the case.

Or could it be reading S1KA?

Its honestly so hard to tell, but i have no idea if the value would affect my volume control issues or not, perhaps there is another cap at fault somewhere?
I dont think the caps were to blame for the OT blowing up, as they dont appear to be shorting on my multimeter like you would expect with a leaky cap.

Anyway, its probably ideal to recap the whole radio, but that will be a fair bit of work.

Any other caps that could be causing the issue that you can think of on this schematic?

Perhaps this volume issue is the result of another cap altogether thats leaky?
Perhaps there is something else thats failed that could still potentially blow up the OT
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Old 1st Jul 2021, 2:52 am   #39
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

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
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Old 1st Jul 2021, 8:17 pm   #40
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Default Re: Winding a new output transformer for a Philips B5G64A Radio

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.
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