sunglasses needed for my IIC+ chassis!***REVISED, FINISHED!!

[hifivic]

I have a friend that's been a high end home audio tech for 40 years that specializes in vintage gear repair and restoration. He did a tube socket pin repair for me and while he was at it he added some elbow grease!

 

[Elpelotero]

****! You weren't kidding!

What the heck did he use??!

P.S. I would suggest putting some shellac on the transformers to protect them from rust. It looks like he stripped off the epoxy?

 

[hifivic]

12 sheets sandpaper....1000,1500 & 2000 grit, a wire wheel brush and assorted small wire brushes. As per your suggestion I realize that I need to shellac on the trannies.....any specific brands or types I should use? He wondered if the pre-amp tube next to the OT came with a shield from the factory since it's so close to the trannie?

 

[Elpelotero]

I just went to Home Depot and picked up the only brand of shellac they had. I'm not a shellac connoisseur though...

 

[CoG]

If that's Zinser Bullseye, which is what Home Depot usually has, I wouldn't use it... I don't think it's intended for more that "hot sun" temperatures and it'll probably smell funny for years once it heats up.

I could be wrong though... I only use it on baseboards and outdoor tent frames

 

[MesieBooga]

Thats one clean machine! 8)

 

[Elpelotero]

If that's Zinser Bullseye, which is what Home Depot usually has, I wouldn't use it... I don't think it's intended for more that "hot sun" temperatures and it'll probably smell funny for years once it heats up.

I could be wrong though... I only use it on baseboards and outdoor tent frames

I think that's the one. It comes in a yellow can, cost me about <$10. I never got around to putting it on, it's just sitting there. But if you can recommend something better, let me know.

 

[CoG]

If that's Zinser Bullseye, which is what Home Depot usually has, I wouldn't use it... I don't think it's intended for more that "hot sun" temperatures and it'll probably smell funny for years once it heats up.

I could be wrong though... I only use it on baseboards and outdoor tent frames

I think that's the one. It comes in a yellow can, cost me about <$10. I never got around to putting it on, it's just sitting there. But if you can recommend something better, let me know.

Sorry man, wish I knew. The trannies in my MkIII don't get nearly as hot as the tubes, but they get pretty warm, and I am not sure that Zinser's stuff, which AFAIK is just meant for wood, wouldn't turn into smelly peeling goo on your C+. That would suck.

 

[srf399]

Looks very clean but, I would have freaked on him for doing this to my amp. Kind of like sanding down a 1955 T-Bird without the owners permission or the milkman taking my wife to a hotel room. Sorry, this is just my opinion.

Also, all things being equal... If I'm looking at two vintage amps, one is original and another is sandpapered and painted with some goo from Home Despot... I'm going with the original... non touched amp every time and would put vintage value on it with the blemished amp selling for something less than full value. This guy depreciated your amp... very unprofessional. If you wanted it cleaned up and not have the value of the amp tainted you should have sent it for reconditioning to Mesa. :roll:

Also.. why would he wonder if the preamp tubes came with shielding covers? You can see the base nub where the covered grips onto it clearly on every socket. If this guy is so experienced I would have expected him to put new ones on long before sanding down your amp. Sorry... maybe I'm over reacting but I'd have been breathing fire if that was my amp.

 

[dancullinane]

OOOOH looks nice...but did he sand off the dates written on the underside?

 

[stokes]

40 years in the business and he didnt know better than to sand the laminates on a tranny?And he did sand off the date/code on the chassis.How many people are going to look inside an amp and see how clean the chassis is?Sorry,but I'm with srf399 on this one,hey,if you like it thats great,but it serves no purpose and if those laminates start shorting it will be detrimental in the long run.

 

[hifivic]

Wow.......chill out everybody 8) . the trannies had rust on them as the protective coating had come off, the only way to save them from eventially being eaten alive was indeed to sand them down. This project is not complete as the 2 final steps are to paint them black again as they were shipped from Mesa but this time with a Rustoleum type paint and then coat them with a polyuerathane. I was in the high end hi-fi business for 35 years and we used to re-store old McIntosh amplifiers and Audio Research amplifiers the same way, it is imperative to get the rust off of non-replaceable trannies, paint them and lastly coat them. We certainly weren't foolish enough to sand off the MB initials and + signage!

 

[Boogiebabies]

I'm sorry, but I don't recall everyone pitching in to buy this amp for Vic.
We have no right to even imply what someone should or should not do with their property. It's just a few markings from a marker. The laminates do not look sanded to me, so no foul their either. It's not like the guy went Rhino Bucket on the amp.

 

[Elpelotero]

When you're done repairing it, a short tutorial on this very page about the process you went through restoring the transformers would be appreciated!

 

[bpm91]

I think you guys missed a few spots.

 

[MesarockerMk2]

Hey Thought I would offer my technical expertise. I have an extensive background in DC & AC machines (ie) motors, actuators, armature & field coil assemblies etc. Any time you wrap copper wire around a lamination stack, insulation is critical. Any short between the stack and the conductor results in a catistrophic failure. Part of the manufacturing process is to test for shorts between the coil windings and the lamination stack or core using a hypotential tester. The hypot tester puts a high voltage, low current signal between the coils, and the stack. Typically in the manufacturing process the transformers are vacuum impregnated with a insulating varnish, baked in a oven to cure the varnish, and tested again before being installed into the circuit. If the insulation is damaged by sanding off the varnish the rusults would be evident by a failure and you would see more than smoke. Note: The hypot testing is done with the transformer out of the circuit to avoid damage to the other components. Leave this to the experts! If all that has happened is some of the varnish has been removed from the laminations you can get some red Glyptol insulating varnish from a electronics supply, or a clear insulating epoxy to coat the laminations. This would protect the iron from rusting, and help prevent shorts. I agree with the others. Don't use laquor or varnish that is designed for use on wood unless smoke and smell is part of your pyro effects. Regards, Billy

 

[Elpelotero]

sounds like some sound advice right there.

 

[Dan__O]

to short the windings out to the stack, you would need to remove the laminations from the transformer (easier said than done believe me :lol: ) and damage the bobbin / mylar cheeks somehow.
The varnish (usually polyurethane off the top of my head, but could be wrong) is predominantly there to stop hum / buzz from the laminations, to protect the laminations from rust, and to further separate the laminations to stop eddy currents (heat generating recirculating magnetic current). Unless you soaked the transformers in acetone, I think it should be fine. just get a can of polyurethane, and spray the outside of the stack lightly, do a few coats, letting it dry fully between coats. - avoid spraying the windings as MesarockerMk2 pointed out. - better to be safe.

Be prepared for your transformer to stink for a month or 4 though.

 

[stokes]

I aint no engineer,but since I started learning about repairs and such back in the '60's everyone I have learned from,including one old timer who was a design engr for RCA since the 1930's,always recommended leaving the rust on a tranny alone,sanding would accelerate any shorting between the laminates,causing the aforementioned "eddy currents".I have a couple amps I built a long time ago with trannies from the '50's and have had rust on them since I got them used and are still working fine.Old habits die hard,and I wouldnt sand or recommend to anyone to sand a tranny.

 

[hifivic]

to short the windings out to the stack, you would need to remove the laminations from the transformer (easier said than done believe me :lol: ) and damage the bobbin / mylar cheeks somehow.
The varnish (usually polyurethane off the top of my head, but could be wrong) is predominantly there to stop hum / buzz from the laminations, to protect the laminations from rust, and to further separate the laminations to stop eddy currents (heat generating recirculating magnetic current). Unless you soaked the transformers in acetone, I think it should be fine. just get a can of polyurethane, and spray the outside of the stack lightly, do a few coats, letting it dry fully between coats. - avoid spraying the windings as MesarockerMk2 pointed out. - better to be safe.

Be prepared for your transformer to stink for a month or 4 though.

You are 100% correct concerning shorting the windings, **** near impossible as you would indeed need to disect the transformer and strip the coating from the bobbin.........some of the comments in this thread are downright comical and way off base........the most important part was to eliminate the rust....period. My former business had re-stored dozens of high power McIntosh, Audio Research and Dynaco amps the very same way. I watched McIntosh Labs service techs perform the same task the very same way when I toured their facility. They used a Rustoleum black paint and applied it with 1" wide foam brushes which prevented any future rust as long as the original rust was indeed sanded off first.