"stop" line on sony receiver

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Can someone clue me in on how the stop works? If I disconnect the stop wire from the power control IC I can get the receiver to power up.
Thinking I had a bad control IC, I changed that. When I connect it, the line goes low, and the receiver will not power up. If I remove it, the receiver will power up sort of, but not completely. I really think the digital control board has a fault in it, the ry power voltage (from control board to power supply) reads about 2.5 where it should be 5 or so. Of course, this is only when I have the stop line removed. With the stop line in, =dead.
sony strda30es.
Probably should just punt, it is not worth much these days, but was $600 8 years ago...

Anyone have any helpful hints?

Thanks!
 
you could have a problem in the relay driver as well. i've seen -DE series receivers with bad relays, and that brings the standby voltage down to 6V from 12V and you lose most of the 5V cpu standby voltage. the drop in voltage takes place when the shorted relay coil gets energized. if the relay is ok,you can bypass the CPU PWR_RLY signal by disconnecting it from the cable socket (extract the contact from the plug body or if it's one of those connectors that clamps bare wires, just plug the cable into the connector with that wire sticking out) and tying the power board end of it to the standby +5V through a 1k resistor. you might want to wire a switch into the test rig, so you can turn the relay on and off long enough to take measurements. i would also run the receiver with a 100W light bulb in series with the power line, just in case it's an amp problem. i just helped a co-worker troubleshoot a sony with no display. as it turns out it was a fried amp and a blown fuse to the transformer. somebody had stripped speaker wire over the top of the amp and there were copper strands scattered all over the amp board.
 
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