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Hoffman Amps Forum image Author Topic: OT wire colors            (Read 3010 times)

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Offline Geezer

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OT wire colors          
« on: June 18, 2005, 05:18:09 am »

  Hoffman Amplifiers
    > Tube Amp Building - Tweaks - Repairs
        > OT wire colors      
 
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Leevi
Junior tube assistant
Posts: 115
(3/12/04 9:23 am)
 OT wire colors
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 Are there any standards for the wire colors used in OT:s
I own an OT (a brand new AC30 OT clone) made by Dagnall Electronics (UK?). There are red, white and red wires on the primary side and black, blue and green on the secondary side. I think I'm quite sure of the primary wiring but how to determine the secondary side? So far I have not get any answer from the manufacturer.
/Leevi
 
Tiny Daddy
I will work on all amps
Posts: 547
(3/12/04 10:00 am)
 Re: OT wire colors
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 Those wires can be any color.
 
gammelnalle
Junior tube assistant
Posts: 21
(3/12/04 12:31 pm)
 Re: OT wire colors
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 what is the problem ? you seem to be a VERY good amp-builder so I guess you have some meters.

The seconddary should be 4 AND 8 ohm so the lowest reading ought to be the 4ohm...
 
Tiny Daddy
I will work on all amps
Posts: 550
(3/12/04 12:40 pm)
 Re: OT wire colors
--------------------------------------------------------------------------------
 You could put a few volts AC on the secondary and measure voltage on the other leads to determine turns ratio.
 
6G6
Junior tube assistant
Posts: 120
(3/12/04 12:51 pm)
 Re: OT wire colors
--------------------------------------------------------------------------------
 What Tiny Daddy said.
The 6.3V heater taps work well for that.
 
Leevi
Junior tube assistant
Posts: 116
(3/12/04 1:51 pm)
 OT colors
--------------------------------------------------------------------------------
 Thank you for the tips. The problem with measuring the DC resistance on the secondary is that my voltage meter doesn't show any difference between the black, blue and green wires. I think the only way to solve that is to put AC on the primary and measure the ratio as you proposed.
/Leevi
 
Rotting27
Posts: 126
(3/14/04 10:12 pm)
 Re:
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 Of course some transformer widners can get nuts, but it seems evident that on the primary side that the reds go to the plates, and white is the CT.

On the secondaries, measure the DC resistance between all the leads two at a time. You will notice that there is a larger resistance between a certain two than any other two. One of those goes to ground, the other is your higher impedence tap. It doesn't matter which you use for ground and which is used for the high impedence tap. I'm guessing that you could go black to ground green to the jack or the other way around. Like I said, either way will be work just the same in an AC30 circuit.
 
 
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