hifi engine

Sx-1250 Protection circuit bypassed.

I just bought this on ebay and was told everything worked fine. I never seen so much filth in anything. The am, and phono don't work and when I pulled the boards found someone had soldered wires across the power relay.
There is also a safty relay for the phono that i'm guessing isn't energizing due to the main power relay being bypassed. It energizes for a second on power up and down.This is my first pioneer and i'm looking for someone who can maybe save me some time. I'm going to finish cleaning the boards and remove the jumpers. Put it all back together and try and figure out why it was bypassed. Any direction here would be great. Thanks Jeff

I guess, you have downloaded

I guess, you have downloaded the repairmanual.
A hint before, at the rear side you can remove the bridges between the pre- and mainamplifier. With a normal cinch cable you can connect the preamplifier ( and everything before , tuner, etc. ) to an external amplifier and check the complete item before the main amplifier.

If the amp. does work, please remove first the relay´s and test the coils. If there is a resistance between the two connector´s , these should be o.k. . Next check the switching contact of the relay`s.

On page 19 you see the shematic of the protection circuit.
The signals are coming from the overload detector and the DC voltage detector. If the amp. does´nt work, I think, one ( or both ) of the main amplifer´s have DC voltage in the output. You can test it with a multimeter. Than fix the main amplifier with DC ( left or right ) and check the main transistor´s. If there are some ( or all ) of them defect, test the transistor´s before and replace all.

... additionell: the relay

... additionell: the relay in the phono preamp is switching only between phono 1 and phono 2.