which wire is pos/neg


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Old 11-11-20, 02:41 PM
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which wire is pos/neg

I'm trying to connect a power cable to a turntable pre amplifier ( solder) and I need to know which wire is positive and which is neg going to the transformer, here is a picture. it is a radio shack made in the 70s or 80s. The pic will not upload, is there a DIY for that?
 
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Old 11-11-20, 02:59 PM
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Instructions for posting pictures are at the top of every forum section.

If the transformer on the AC part of the circuit there is no positive or negative since it's alternating current. If it's DC then you can check it's polarity with a multi meter.
 
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Old 11-11-20, 03:57 PM
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42-2930 was the little preamp.
42-2109 was the better preamp.

I have the schematic for both of them. Neither shows power cord to transformer polarity.

 
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Old 11-12-20, 12:42 AM
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It is 42-2101a

It is a 42-2101a looks just like the one in your pic. I can't mine to upload.
and the only difference is the ground wire post is on the test, opposite of yours.
 

Last edited by 412know1seeks; 11-12-20 at 12:46 AM. Reason: additional info
 

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