On Jun 5, 11:36*am, sorry-spammers ""w9wi\"@(sorry-spammers)" wrote:
I suppose this is more repair than homebrew, but since at least it's in the right spirit I hope you'll indulge me...

Took a lightning hit on the power line about a week ago. *The ham antennas were disconnected so the ham gear survived, but some of my computer &
consumer gear wasn't so lucky.

In particular, a Sony XDR-F1HD HD Radio tuner.

It actually works fine. *However, there's about 600mV of AC between ground and the shield sides of the audio output and antenna input jacks. *As you
might guess, this leads to a bit of a hum problem!

Suspected leakage across the power transformer (between primary & secondary) but I'm not finding any with an ohmmeter. *There's absolutely *nothing*
on the primary side of the transformer except the power cord -- no capacitors to ground, nothing like that. *Silk-screen on the power supply board
does say there's a fuse *inside* the transformer but obviously that's not going to be a source of a ground fault.

I'm confident the fault is in the Sony (and not the audio amplifier or a damaged antenna cable) since if I connect the same audio cables and antenna
to the old analog tuner it works fine.

Anyone have any good ideas where to look?

I guess I could:

- Come up with an isolation transformer & just run it that way. *(it only draws 13 watts)
- Build up an external power supply. *It only needs +5.2 and +10.5V unregulated, and the connection points are silk-screened on the board.
- Live with it & just kick in the high-pass filter. *(and use the analog tuner if I want to listen to a program -- the Sony is for DXing..)

--

Doug Smith W9WI
Pleasant View, TN *EM66

First thing I would do is check my cables, sounds like you have an
open ground or a ground loop among other possible problems listed. Why
do this first? Its EZ.

Jimmie