Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jack_Hester on January 17, 2015, 02:41:20 pm

Title: Transformer rewinding service wanted.......
Post by: Jack_Hester on January 17, 2015, 02:41:20 pm
Just finished up what I thought was an easy repair on another Gibson Thor.  New canned capacitors (two 3 x 20uf) in the PS.  New tubes. 

Originally, one of the canned caps had a blowout, even after the amp had been brought up on a limiter over about an hour (25, 40, 60, and 100 watt bulbs).  Replaced both cans, and brought it up again.  Bias was 37mA for a plate voltage of 470vDC, on the JJ 6CA7's.  And, it sounded really good when tested with the guitar.  Wonderful tonal range. 

After a while of just sitting with full power on, it blew my 3A fuse.  Brought it back up on the limiter, no tubes.  Never went past the 25 watt bulb this time.  Super bright.  I won't fool with it any more today, but next week I plan to lift the PT secondaries and put it on the limiter again.  Got my doubts about the PT, but I'm not ruling out one of my new canned caps being bad. 

I'll have more on that test later. 

But, I got to thinking after I searched the Hammond site for a replacement with the same footprint.  This one has a rather large, as compared to theirs.  I measured 720 to 730vAC across the secondaries, when it was working.  It's basically the same as my other two.  So, I searched for a 720v - CT.  My thinking was to see if anyone knew of a good place to have this one rewound.  Never had one done before, and thought that it would be worthwhile to try. 

I'm hoping that someone here knows a good source for such work, in the event that mine is burned.  Thanks for any info that you can provide.  Have a good one. 

Jack
Title: Re: Transformer rewinding service wanted.......
Post by: kagliostro on January 17, 2015, 05:02:22 pm

Ciao Jack

At DIYItalia we have a pair of friends that wrap transformers for herself barehanded

all begin with a broken transformer to rewind and little money

Franco
Title: Re: Transformer rewinding service wanted.......
Post by: Jack_Hester on January 17, 2015, 06:41:17 pm
Found a service: 

http://members.tripod.com/tubes_tubes_tubes/transformerrewindingservice/ (http://members.tripod.com/tubes_tubes_tubes/transformerrewindingservice/)

And, they have Gibson Thor listed near the bottom of this page: 

http://members.tripod.com/tubes_tubes_tubes/transformerrewindingservice/id69.html (http://members.tripod.com/tubes_tubes_tubes/transformerrewindingservice/id69.html)

I'm going to email them for information.  I'm still going to look for others, but at least they list plenty of instrument amp transformers.

Jack
Title: Re: Transformer rewinding service wanted.......
Post by: Deric on January 18, 2015, 02:06:24 pm
Heyboer have done a couple for me and I've been really happy with the price and service...


http://www.heyboertransformers.com/ (http://www.heyboertransformers.com/)
Title: Re: Transformer rewinding service wanted.......
Post by: Jack_Hester on January 18, 2015, 02:57:49 pm
Quote from: Deric on January 18, 2015, 02:06:24 pm
Heyboer have done a couple for me and I've been really happy with the price and service...


http://www.heyboertransformers.com/ (http://www.heyboertransformers.com/)

Didn't know that they did rewinds.  Good to know.  Thanks. 

Jack