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John,

As Albert said there is a lot of good information on the 576 repair in general and the HV transformer in previous posts. As you read through those posts you will learn that the HV transformer in the 576 is unique, the ones potted in the brown epoxy fail often, the ones potted in the later black silicon are still running, the cut off is around 3000000 (not sure if I put enough zeros in the serial number… but starting around the ones that start with a 3 in the first digit was when the black silicone ones started showing up). As far as repair goes… there is some data on the web on how to gently remove the old brown epoxy, however, rewinding is a chore and most on here will tell you "impossible" at worst, and "maybe if I ever finish my home made winder" at best. So I decided to find a company that would make a new one for me. With the help of others on this board, I was able to secure a transformer winding and specification drawing, then I found a company willing to make one for me, if I purchased five of them. It turned out to be a less than optimum economical repair (though still much much less than a working and calibrated one on eBay), however, it was also a really good and rewarding learning experience bringing a 576 that was sold "for parts" back to life.


I was on eBay about a week ago and noticed that someone was selling the entire HV unit with the newer version of the transformer as well as the entire readout display (another part with unobtanium parts (ICs)) for what I thought were very reasonable prices. I was tempted to pick them up… then changed my mind as they would be really helpful for someone else struggling to get their 576 going again. I actually was planning to get on here and let others know about it ... I have not checked if they are still there.


Finally, if the one on eBay is gone… I have a few transformers for sale that were left of the five I bought for the initial run. It does not look like either of the OEM transformers, but it works very well and will fit in the original location easily.


Dave

Dave:

Many thanks: I've sent you an off-list reply.


John

Has anyone ever been able to find the winding specifications for any other HV transformers (specifically the 647)? It seems like it would be good to find and archive as many as possible before they're lost forever.

647 EHT transformer info posted to the group photo section (I hope)
I am pretty sure the transformer is same for 647A scopes
Chris HJ

Thanks, that's exactly what I was looking for.

Andy

John,

I never did get your off list email.


Dave

here it is: sorry Group.

Dave:

Many thanks for your concise summary of the problem. There are so many posts with repeated text and side-issues that it's quite difficult to see the wood for the trees!

The failure in this case has been posted by a guy in Germany on the UK vintage radio forum, and I've been attempting to guide him on fault diagnosis: see

If you have a transformer which would work in his 576, would you mind if I forward him your email address?

Thanks again

John

Hello Dave,

I'm the guy from germany with the HV transformer at fault in an otherwise quite well working 576. If you happen to have one of those rewound transformers left, I'll be interested of course.

cheers
Martin

I just happened to see your post and then eBay item number 121520632728
right after. It is a 576 that is being parted out. Maybe the transformer
is still available.

DaveD

I sent you an email to the email address that you used to register on this group.

Thanks,
Dave