Mystery transformers

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johnnyreece
Posts: 1072
Joined: Thu Jan 26, 2012 2:05 am
Location: New Castle, IN

Mystery transformers

Post by johnnyreece »

So, in my accumulation of fine junque, I picked up some mystery transformers. One is cooked for sure, with a short on the primary. Got another PT that turns 120VAC to around 40VAC. Not sure of a plan for that yet, but what I am curious about are this pair:

[IMG:1024:1365]http://i218.photobucket.com/albums/cc165/moto_xxx199/23D97DD0-5C4F-462D-9EB8-A15BF0B623DF_zpspq9m8q0y.jpg[/img]

They both appear to be output transformers, with a primary resistance of 300+ ohms, and negligible resistance on the secondary. So, after juicing the primary, I get, what appears to be, a 3K:1 ohm ratio on one, with a 3K5:1 ratio on the other. Does this sound like something real? One red flag is that one tranny has a bare wire coming out of the secondary side, and it has no continuity with anything. Anyhow, I thought I'd ask here to see if these are anything more than crusty paperweights.
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RWood
Posts: 254
Joined: Sun Jul 07, 2013 7:56 pm

Re: Mystery transformers

Post by RWood »

I used a 120:40 as a 20v bucker using 1/2 secondary to bring 120-125v wall supply down to 100-105v for browning my plexi.
I'm thinking of making it switchable -40 to -20 to bring up caps and break in new builds slower after current limiter.

I had a Fender OT with bare wire out of secondary that was soldered to frame for ground which had come loose. It had only 4/8/16 secondaries with no other ground.
Last edited by RWood on Tue Apr 21, 2015 6:31 pm, edited 1 time in total.
If it don't get hot and glow, I don't want it !
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johnnyreece
Posts: 1072
Joined: Thu Jan 26, 2012 2:05 am
Location: New Castle, IN

Re: Mystery transformers

Post by johnnyreece »

I'd assumed the bare wire was connected to the secondary, but it has no continuity with anything...Could very well be another paperweight. I might give it a shot at some point and see if it explodes.
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Structo
Posts: 15446
Joined: Wed Oct 17, 2007 1:01 am
Location: Oregon

Re: Mystery transformers

Post by Structo »

Sometimes they use a wire from the PT transformer to ground the frame.
Tom

Don't let that smoke out!
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