toasted V72A input transformer - any ideas on who to fix it?

so ive got a V72A with an open winding in the secondary here, and I need to get it fixed. I emailed Oliver over at TAB but haven't heard back from him yet, so I was wondering if anyone here can give me some reccomendations for people to talk to about rewinding.


thanks!

-Bryan Sours

SEND to CJ for dissection!!! I know he did the V72 input before, but there are many versions out there.

try calling him. he picked up first ring when i tried a while back. he's a really nice guy.

http://www.tab-funkenwerk.com/

Oliver can wind you a new one or repair the old one. He has the tools and the recipes. He might be on vacation...

Good luck.

mike

You could also try haufe http://www.haufe-uebertrager.de/, I believe they originally built a lot of these transformers those days.

Michael

I've heard of these transformers going bad. But for the life of me I can't see anything in the circuit that could cause trouble. Especially in the secondary. It must be insulation breaking down or something.

Anybody have a clue?

Yeah, something about the enamel breaking down.

Here we go:

http://www.groupdiy.com/index.php?topic=4392

Halfway down.

Be careful with that mercury/lead stuff around the primaries.
Nasty.

I am working on some blown iron for Jens right now, and a trans for Larry, so kind of busy right now.

You can slap a Jensen (Ollie is gonna kill me!) on the front of that thing and I bet it will sound the same.

You can dis assemble that input, as it is disk type. Pull off the disks and ohm them out. Could be just the splices. The hookup wire on some V modules will vaporize if you touch it, so use new wire for the breakout.

Hey CJ (and all),

I've too have a V72a here with an open secondary winding. I found the thread in which you mention "mercury/lead" around the primaries. What is that about? The solder used in this old German stuff always has a different smell to it when reflowed - any idea about that?

Best,

Tim

The V76 had a mecury/lead tape covering one or more coils, that stuff would obviously not exactly be healthy. Dunno how bad it might be though if you touched it. The V74 has a bad habit of leads braking in the coils as far as I remember due to some foam used in the original construction which falls apart and releases some acid (?). Since the V72a is out of the same family, I could imagine the same thing happening there. I've never opened the can to examine the transformer but I have several V74 with funky or broken input irons. I don't know whether the V72a really has the same mercury issue as the V76, but if you carefully opened it, maybe with a lot of fresh air and wearing gloves, you should be able to see the foil if it was there. It looks like aluminium foil, kindof like chewing gum paper, wrappped around a coil. My guess is that the V72a doesn't have that foil.

If I recommend something dangerous someone please correct me!

Maybe it's worth opening the can to see if the wire broke at the soldering joint and could relatively easy be fixed.

Michael

Wear rubber gloves and dust mask.

Dismantle everything onto a piece of polythene (like plastic dust sheet), leave the mercury/lead tape and other sh*t on the polythene, drop your gloves and dust mask in, wrap it up and take it to your local civic amenity (aka - dump) to be disposed off. Don't forget to wash your hands afterwards.