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Tektronix high voltage transformer rewind and vertical output for 7104

Jean-Paul
 

Hello all, I have been following this most interesting thread.

As a retired magnetics designer and manufacturer, virtually all commercial firms are fabricating mass production in China. The set-up is costly and runs of less than 1000 difficult to get a quote. Your experience with Sun is typical.

Some HV transformers need special core shapes, custom bobbins, litz or very fine guage wire and/or a special winding machine. So not easy to design, tool or build.

Finally the impregnated secondaires needed a vacuum oven to pull air bubbles out of the epoxy, plastic or varnish liquid before it cures solid. Any voids or air bubbles remaining will eventually ionize and lead to carbon tracking and failures.

In mid 1980s it took us 1 yr to design and to debug the potting process and materials for a 12 kV custom avionics CRT module with transformer and voltage multiplier! We made 1000s but always got some DOA after potting, yields increased from 50% to 98% after the procedure was optimized.

Just the rumblings of an old retired EE!

Bon courage,

Jon in Paris

Mark Vincent
 

I contacted Sun Transformer by email and letter a month ago. Nothing from them. They had my email address, street address and telephone number so contact would be easy. I have contacted other people and places for some time before posting here. No one replied. I can only assume they lie about doing what they say they can do and/or have too much work and money already. Ignoring someone asking questions is sure way to drive that person away and get a well deserved bad reference. No money can be exchanged with this kind of attitude. Maybe someone will eventually say how much and the time frame to do the work. That one will likely get my business. It would be nice to see my 7904, 454 and 647A working. My 7934 is working fine. No need to rewind the transformers in my 7934. If anyone can make new transformers for the ones that commonly go bad (new cores, wire, insulation, etc.), that would be great. The 500 series were known for having breakdown problems.

Mark

Dave Daniel
 

I remember your posts about that, I guess back in 2014. I had just purchased a 7934 that blew fuses and was hoping that the root cause was not the transformer.

It turned out that the PO was using 2 A fuses when the ‘scope needs a 4 A fuse (it’s written right on the rear panel!).

Once I installed the proper fuse it has worked very well.

I haven’t fired it up since moving back to FL. I guess I need to do that.

DaveD

Sent from a small flat thingy

On Aug 1, 2019, at 14:20, Karin Johnson <karinann@...> wrote:

A few years back I did a successful rewind of the HV transformer in my 7934. It is still working to this day. Now I don't really want go get into the transformer rewind business, but I will share a potential resource that might be able to help. I'll warn you up front, it won't be cheap.
The company I found that might be willing to do a rewind for you is Sun Transformer, A division of STC, Inc. Their phone number is 618-643-2555.
The contact I had was a gentleman by the name of Les Vaughn. The time frame was from April of 2014.
Just a quick note here, there have been several other folks on this list that have successfully rewound the 7934/7834 HV transformer. It is not
easy but can be done if, and only if the bobbin and core are still in good shape.
Good Luck,

Karin Anne Johnson K3UU
Palm Harbor, FL


Karin Johnson
 

A few years back I did a successful rewind of the HV transformer in my 7934. It is still working to this day. Now I don't really want go get into the transformer rewind business, but I will share a potential resource that might be able to help. I'll warn you up front, it won't be cheap.
The company I found that might be willing to do a rewind for you is Sun Transformer, A division of STC, Inc. Their phone number is 618-643-2555.
The contact I had was a gentleman by the name of Les Vaughn. The time frame was from April of 2014.
Just a quick note here, there have been several other folks on this list that have successfully rewound the 7934/7834 HV transformer. It is not
easy but can be done if, and only if the bobbin and core are still in good shape.
Good Luck,

Karin Anne Johnson K3UU
Palm Harbor, FL

Kyle Rhodes
 

Unfortunately I'm no help with the rewind -- but I have a 7934 transformer
I'd like rewound as well. If you find someone, sign me up too!


Thanks,
Kyle


--
KSR Amps / Rhodes Amplification, LLC
Kyle Rhodes
(513) 480-2677
kyle@...
http://www.ksramps.com
http://kylerhodesdesigns.com


On Thu, Aug 1, 2019 at 12:48 PM Mark Vincent <orangeglowaudio@...>
wrote:

I have a 454, 647A and 7904 that have bad high voltage transformers that
need rewinding. I am looking for someone that can and will do these with
time frames and prices. I am also looking for the vertical output IC for a
7104. If the transformer for the 7904 cannot be rewound, I will look for
the A version (preferred with options 3 and 78). I have the transformers I
can send off to someone who will rewind them. Thanks.

Mark



Mark Vincent
 

I have a 454, 647A and 7904 that have bad high voltage transformers that need rewinding. I am looking for someone that can and will do these with time frames and prices. I am also looking for the vertical output IC for a 7104. If the transformer for the 7904 cannot be rewound, I will look for the A version (preferred with options 3 and 78). I have the transformers I can send off to someone who will rewind them. Thanks.

Mark