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From: Bob F <bobnospam@gmail.com>
Newsgroups: sci.electronics.repair
Subject: Altec Lansing ATP3 Speaker system transformer failed.
Date: Sun, 28 Apr 2024 16:08:57 -0700
Organization: A noiseless patient Spider
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This speaker system I used on my main computer died yesterday - no power 
at all.

I traced the problem to the transformer, a 12.5V 2.5 A TP57U25F from Ten 
Pad Industrial. Testing the transformer coils, neither the 117V input or 
the 12.5 V secondary show conductivity - they are both open circuit. The 
fuse for the primary circuit was not blown.

My question here is, if both coils are open circuit, does this suggest 
that a major short on the PC board got the transformer too hot so it 
tripped temp circuit cutoffs in both coils, so it is unlikely that 
replacing or fixing the transformer will fix the speaker? Or, is this 
kind of failure common for such transformers?

If I wanted to try a different transformer to test the board, what 
should I want the transformers open circuit voltage to read on my 
Greenlee DM-20 DVM.  Should that be 12.5V? I do have a variable voltage 
variac I could use to adjust a slightly higher voltage transformer down 
to 12.5 or whatever should be needed.