"Jack Twilley" wrote in message
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I accidentally reversed the polarity of my DC power supply. I blew
the fuse in my TNC, but I can't find a fuse in my TR-7400A and the
only fuse I see in my TS-520 appears to be for the AC power supply.

What sort of damage could these radios have suffered?

Jack.
- --
Jack Twilley
jmt at twilley dot org
http colon slash slash www dot twilley dot org slash tilde jmt slash
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There is a diode on the 7400a that is there to stop damage in such an thing
happens.

It is either in parallel to ground off the 12v lead in in the rig , or it
may be in series. But most likely it will be in parallel.

It will be easy to see as it will be burnt and probably busted open. It is
also shorted. Hopefully it went before the rest of the radio did. But if
it did not stop there, look at the Voltage regulator (s) chip (s) and you
probably blew out the rcve audio stages also.

Why was there no fuse is my question on the 7400A line?

As to the TS-520, it runs on AC. Why is there a DC power supply on it?

Dan/W4NTI