Hi everyone

I just picked up a Tek AA501A distortion analyzer with the two SG505
oscillators. The AA501A seems to have a problem and I was wondering if
anyone can help. The unit powers up and the volt and db functions seem to
work ok, maybe just slightly out of calibration. When I switch to the
distortion mode (THD+N) it does seem to work but when the any of the output
range percentage buttons are pressed they don't respond. It seems the led
display is locked in 3 digit resolution with no decimal points.

The units are in almost new condition and I would like to get it
working properly. I opened it up and could not find any obvious problems
except a 3 pin jumper with the plug with wires placed only on two of the 3
pins. I plugged it on the 3 pins and it still works the same. I believe this
is a power plug which feed one of the other boards. I am guessing someone
was in there, and intentionally left it this way not sure why.

Thanks
Frank