On 1 Nov 2005 08:14:11 -0800, wrote:

Thank you all so much for the excellent information.

Last night I had the unit on my bench, multimeter in hand. The first
thing I did was to check the grounds. One on the main board showed
signficantly higher resistance than the others so I re-tightened all of
them and cleaned all the ones on th main PCB. I re-checked resistance
to ground from all those points again and got a consistent 0.3 to 0.4
ohms (not accounting for test cable loss).

I plugged the unit back in and voila, no more "PROTECT" fault. My jaw
was agape! I was thinking I needed to go out and buy a Powerball
ticket. This NEVER happens. I was convinced that one of the output
transistors had failed but lo, twas no more than a poor ground.
Amazing.

I'll go back and put a heat sink onthe upc2581. This receiver runs
fairly warm generally and that is good counsel.

re5513


I'm glad it was something simple. Those Sonys are tough to repair and
are often unreliable after they've blown the outputs. Never use NTE,
or other subs. I didn't think the grounds were a problem on the newer
receivers; I'll keep that in mind next time I work on one. I like to
solder a wire from the board to the chassis in cases like this. At
least put a star washer under the screw to make a better connection.

If you heat sink the IC, be sure to use an insulator between the IC
and heat sink. There's B+ on the IC case.
Andy Cuffe

-- Use this address until 12/31/2005

-- Use this address after 12/31/2005