Moved Here - Type 547 HV Transformer Repair

[Cubdriver]

<--------Admitted grouchy old bastard. The difference is that I freely share information to anyone who asks. The grouches on that list for some reason tend to be stingy with info and if you're not part of the "click" downright rude.

Mike, I gather you're referring to the Tek group on the Book of Faces? (Haven't visited Zuckerbergland in many years now) It's very frustrating when you run into people in this hobby that try to gatekeep information like that - we should be encouraging and helping others, not shutting them out (as I know you agree by the comment above). Stupid and short sighted in my opinion.

-Pat

[Zenith]

I could never wind a transformer myself due to dexterity issues. I was born with Essential Tremors (Google it) that affects my hands (always) and sometimes my legs. It makes fine detail work difficult and sometimes near impossible. And unfortunately as you get older it tends to get worse. So that's why I work with the "big stuff" and you'll never see me doing surface mount work. I just can't do it with unsteady hands. Winding a transformer and dealing with the fine wire would result in a tangled mess. So my preference if I decide to get these HV transformers re-wound is to find someone who has experience doing it and of course compensate them. I think I'll re-join the Tek group and despite some of the grouchy bastards who don't like to share info ask if someone does provide this service.

The beeswax potting doesn't seem too hard to do, and once the transformer is dried out, you could repot it in beeswax without messing with the original potting (which might itself be beeswax). With the vacuum treatment the beeswax should enter into and fill any fissures in the original potting and form a protective coating on the whole thing.

Transformer winding machines are available on ebay - and probably aliexpress.

This one is fairly cheap at £25 and solves a large part of the problem of making one from scratch, which is the turning mechanism with crank and counter.

https://www.ebay.co.uk/itm/272260176256 ... R6qPztjIYg

You'd still have to make something to do the weave, or do that by hand. It looks as if one turn of the handle may produce several turns of the core, which might be a pain. The gearing could be changed to something more convenient. You'd have to put it on a suitable base and rig up something to hold the spool of wire.

There are more expensive ones starting at about £130 which are motor driven and foot pedal controlled, with an electronic counter. There's still no weaving mechanism. Some of them claim to be computer controlled. I'd imagine that means you can enter a count limit, which with the foot pedal lets you concentrate on feeding and weaving the wire, with no distractions. Maybe the speed can be controlled as well.

Then there are the all singing, all dancing CNC models starting at over £1,500, which look as if you set them up, put in a core, and a minute or two later out pops a wound core. They look quite big. OK for an industrial operation, but out of the question for hobby use.

[MED6753]

<--------Admitted grouchy old bastard. The difference is that I freely share information to anyone who asks. The grouches on that list for some reason tend to be stingy with info and if you're not part of the "click" downright rude.

Mike, I gather you're referring to the Tek group on the Book of Faces? (Haven't visited Zuckerbergland in many years now) It's very frustrating when you run into people in this hobby that try to gatekeep information like that - we should be encouraging and helping others, not shutting them out (as I know you agree by the comment above). Stupid and short sighted in my opinion.

-Pat

No. I'm referring to what was originally the old Yahoo group. Don't know what they are called now. I was a member many years ago and ran into less than positive responses to questions I asked.

I am a member of the Farcebook Old Tek Scopes group and I regularly participate. As I stated previously there is one member in OZ who successfully rewound his HV transformer and sort of rubbed everyone's noses in it by stating he would not do it for other members. And there are several of us in that group with the issues I have. But he did state "send me a pristine 4 channel Type 1A4 plug-in" and I'll wind one for you. Kind of a douche bag move I think. Type 1A4's are rare and expensive. By luck I got one real cheap and I'm not about to give it up.

[mnementh]

I'll play devil's advocate here and suggest that the motivation behind that statement was more of "It was a labor of love and I did it for my machine, but the assache involved means I couldn't charge enough for the actual labor involved to do it for someone else."

The plugin offer sortof supports that... there are very few things that could entice the guy to go through that misery again, but the plugin he desperately wants would be one of them.

Having done a number of custom cars/retro rods, there are a lot of custom jobs I did once on one car and sold that I'd never do again unless it was on a cost-plus basis, as in "hazardous duty pay". And I certainly wouldn't volunteer for the misery of making it a "service".

Same with my modded gamer PCs.

mnem
Good/Quick/Cheap : Pick any two.

[bd139]

Rewinding an HV transformer is something I considered multiple times in the past, particularly with the old TQ scopes. Having done plenty of low voltage ones a long time ago it's quite good fun and I'd probably enjoy doing it. It's not difficult to do really but there's always that hierarchy of requirements it builds which turn into having to have a lot of dedicated equipment to do it as the voltages rise. That turns that £200 scope project into a £2000 scope project or spending hours of time on the matter to put your own equipment together. You could turn it into a business but it's niche and the whole sector is full of cheap arses who aren't going to pay for your services. So it'll be a sunk cost. So no one bothers and scouts around for limping scopes until the entire market of working HV transformers is used up.

Worth noting with the transformer winding for high voltages that it's difficult because of the isolation requirements. You can't just spin on 2000 turns and it'll work. They have to be carefully layered and insulated at intervals or they'll arc over. That makes it quite difficult to work in the constraints of keeping it small enough to fit in the original hole and simultaneously not arc over.

Historically I built a couple of E-core ones to generate +/-2kv with a royer oscillator driving it and while they superficially worked and produced the required voltages they didn't last more than a few minutes before arcing out despite keeping it to 200v/layer with insulation max. This was depressing as hell

[Cubdriver]

No. I'm referring to what was originally the old Yahoo group. Don't know what they are called now. I was a member many years ago and ran into less than positive responses to questions I asked.

I am a member of the Farcebook Old Tek Scopes group and I regularly participate. As I stated previously there is one member in OZ who successfully rewound his HV transformer and sort of rubbed everyone's noses in it by stating he would not do it for other members. And there are several of us in that group with the issues I have. But he did state "send me a pristine 4 channel Type 1A4 plug-in" and I'll wind one for you. Kind of a douche bag move I think. Type 1A4's are rare and expensive. By luck I got one real cheap and I'm not about to give it up.

Ahh - gotcha. It’s now moved to groups.io. I think I’m a member, but was never particularly active on it. I do recall that the founder or one of those in charge was rather difficult and pissed a bunch of people off by being heavy handed, thus was born Tek Scopes 2, also now on Groups.io (as is the current iteration of the HP-A-K mailing list - hope they don’t spin off again, the name is already too damned long).

As for the HV transformer, it’s great that he rewound it, but much less so if he’s basically flaunting that then borderline being extortionate about winding one for someone else. An “it was a royal PITA that I choose not to do again” might be how he feels and should be enough of an answer if conveyed, but then again knowing how some people can be super persistent despite being told “No” repeatedly might also have resulted in the plug-in “offer” - kind of like a tradesman offering a _go away_ price on something they really don’t want to do - I don’t want to do this job, but if you pay me 25x the going rate, I will. Not having been involved I can’t say for sure, and the dude may just be a butthole. Either is possible, and that doesn’t make it any less aggravating when you have a sick transformer and lack the means to repair it.

At some point I’d like to give it a shot, just don’t know when that point will be.

-Pat

[mnementh]

I figure if it's not something that is important enough for the bucket list, it's not important enough to worry aboot.

mnem
OTOH, that also appears to apply to "hoeing out my music collection"...

[25 CPS]

<--------Admitted grouchy old bastard. The difference is that I freely share information to anyone who asks. The grouches on that list for some reason tend to be stingy with info and if you're not part of the "click" downright rude.

Mike, I gather you're referring to the Tek group on the Book of Faces? (Haven't visited Zuckerbergland in many years now) It's very frustrating when you run into people in this hobby that try to gatekeep information like that - we should be encouraging and helping others, not shutting them out (as I know you agree by the comment above). Stupid and short sighted in my opinion.

-Pat

I'll play devil's advocate here and suggest that the motivation behind that statement was more of "It was a labor of love and I did it for my machine, but the assache involved means I couldn't charge enough for the actual labor involved to do it for someone else."

The plugin offer sortof supports that... there are very few things that could entice the guy to go through that misery again, but the plugin he desperately wants would be one of them.

Having done a number of custom cars/retro rods, there are a lot of custom jobs I did once on one car and sold that I'd never do again unless it was on a cost-plus basis, as in "hazardous duty pay". And I certainly wouldn't volunteer for the misery of making it a "service".

Same with my modded gamer PCs.

mnem
Good/Quick/Cheap : Pick any two.

I've been waffling between these two points of view as I've read the more recent posts in this thread. On one hand, having gone through a few miserable projects, I can totally understand why the guy who successfully rewound his high voltage transformer wouldn't want to do that again if the experience was that gruelling. That's fine but if that is the case, why wouldn't he flat out say so, that he was able to do a one-off successfully but it was such a pain he doesn't want to do it again? At least that way it's clear why he doesn't want to take on anybody else's high voltage transformers that need to be rewound. Bartering for a 1A4 plugin looks like an example of "no-thank-you pricing". The price is set so high that it scares potential customers off but if someone does stump up for it, the cash windfall or the 1A4 in this case makes it worthwhile.

Then there's the gatekeeping. Maybe that's what's going on here with an "I/we get to have it. Nobody else gets to have it" attitude. The local railway museum is a prime example of that. It's a gentleman's club that the public's allowed in during operating hours only because they pay admission and spend money in the gift shop. The members? They're tolerated because they pay a steep annual membership fee, quite often donate money and materials on top of that, and do the work. The in-crowd gets to play with the 1:1 scale model train set and shit all over anyone they feel isn't chipping in enough to keep their toy running at the same time as they make a big show of conspicuously enjoying it but won't let anyone else have any fun. They have this ex-Chicago car they let everyone else operate and completely ignored one of my best friends and I but they sure remembered we were there when it was time to pass around the hat to pay for it all. We each chipped in $20 to keep the peace but in hindsight, we should've handed the hat back and said no, the people who got to run it should be the ones who pay for it. The 547 transformer guy could very well be another one of these nasty pieces of work, and honestly, there's no shortage of them out there.

[Specmaster]

Just a thought, but are there any transformer manufacturers locally that you could at least approach, eg, a tool transformer or power transformers? I used to work with a subsidiary company of transformer maker that specialised in making power tool transformers and temporary site trannies but also took on small one off and other low volume work for loads of people, some of them only about 1" cubes or smaller?

[Cubdriver]

Just a thought, but are there any transformer manufacturers locally that you could at least approach, eg, a tool transformer or power transformers? I used to work with a subsidiary company of transformer maker that specialised in making power tool transformers and temporary site trannies but also took on small one off and other low volume work for loads of people, some of them only about 1" cubes or smaller?

The thing is that the Tek HV transformer is a small, high voltage, high frequency device with special winding and insulation needs - far different construction-wise from a relatively run-of-the-mill line frequency power transformer. Compared to those, like audio output transformers there’s some black magic in there, so pretty far out of the wheelhouse of a 50 or 60 Hz device manufacturer.

-Pat

[Specmaster]

True, but some might be have the knowledge and the ability to wind them, never know until the question has been asked. The one where I worked also did a lot of neon sign trannies, and they were pretty high voltage IIRC.