Pioneer SX-780 overload problem

drh4683

digital is overrated
Hi,

Ive got an SX-780 with an overload problem. The overload relay clicks out when I change stations on either AM or FM. This is mainly a problem when the volume is advanced higher. I noticed at one time someone replaced the power amplifier module (ECG 1281). Is it most likely the power amp module? If so, I can get 2 new ones for $12 a piece. Just want to be sure.
I dont know my way around HI FI audio too much, as Im mainly a TV tek.
Any info apprciated-Thanks
 
The first thing that I would look for would be an overload of DC. Check Echowars "Sticky" in the vintage section. Another posibility could be "cold" solder joints on the board, thry might have visible rings where the solder joint to the board are o longer connected. if in doubt, give the wiggle test, move the component a little by hand and you will see if the solder joint has broken down, does it happen with other sources, or just the tuning section?
 
It has excessive offset or some leaky caps. Flipping from station to station causes a 'thump', which puts the protection over the edge and releases the relay.

Needs work...possibly more than a simple offset adjustment, although that's where I'd start.
 
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