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 Post subject: Building the Stancor Williamson Amp: 807 PP
PostPosted: Mar Fri 16, 2018 4:36 am 
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Joined: Dec Wed 18, 2013 6:03 am
Posts: 284
Location: Inver Grove Heights, MN 55076
Hello All,

A local Craigslist ad had a pair of power supply and amp chassis as well as what appears to be the proper transformers to build the Stancor Williamson amplifier. The price was too good to pass up, so now I have a new adventure - and questions for the community.

1. One of the output transformers has an open winding. Where is a good place to get it rewound? I believe Heyboer can do it, but perhaps there are other recommendations out there.

2. For the resistors in the amp, should I stick with carbon comp or go with metal film? The power supply resistors will be the ceramic or sand type I suppose.

This should be lots of fun and I plan on keeping the parts 'industrial' as there is no paint on the transformer bells and the chassis are copper plated with patina from years of storage. No rust or gross corrosion seen. My plan would be to just use a clear coat for long-term protection, hopefully not too glossy.

For reference, I will be using the ultralinear circuit found here: http://www.tubebooks.org/file_downloads ... matics.pdf

Wish me luck!

Best Regards,

Greenhorn


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 Post subject: Re: Building the Stancor Williamson Amp: 807 PP
PostPosted: Mar Fri 16, 2018 4:54 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 26448
Location: Detroit, MI USA
Heyboer makes very good quality transformers, I have used them on several occasions and been pleased with the results and the turnaround time. They will wind you a brand new one to the exact specs of the original part, or to any specs you give them.

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Dennis

Experience is what you gain when the results aren't what you were expecting.


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 Post subject: Re: Building the Stancor Williamson Amp: 807 PP
PostPosted: Mar Fri 16, 2018 7:31 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3461
I've fixed a few, very few, open transformers by peeling back the insulation and resoldering the lead to the terminal. It might be worth checking out.


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 Post subject: Re: Building the Stancor Williamson Amp: 807 PP
PostPosted: Mar Sat 17, 2018 2:08 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2172
Location: Saskatoon
I know that Williamson OPT's have an interesting interleaved winding arrangement, but if the output winding is still on the outside as it is with most OPT's, then it may be an easy fix, as Macrohenry suggests, without having to resort to a complete rewind.


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 Post subject: Re: Building the Stancor Williamson Amp: 807 PP
PostPosted: Mar Tue 27, 2018 11:54 pm 
Member

Joined: Dec Wed 18, 2013 6:03 am
Posts: 284
Location: Inver Grove Heights, MN 55076
Update:

I was referred to a place in Maine (TRS in Orono) that can repair/rewind transformers.

Both output transformers were shipped today, with the goal of confirming the 'good' one is truly good and to test/repair the one with the open leads. The testing charge is waived if I use them for the repair.

Budget is kinda tight for this project so I may need to pinch some pennies elsewhere. I will also keep my eyes open for a Stancor A-8072 output transformer for sale somewhere. I did find one on Canuck Audio Mart for a price much lower than the rewind cost, but the ad was from November, 2017, and I doubt it's still available.

Stay tuned!

Best Regards,

Greenhorn


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