Some odd wires spotten in my SX-3700

Elbowgeek

Active Member
I've finally got round to cleaning and hopefully fixing my Pioneer SX-3700 today. For some reason the protection relays have stopped functioning. I'm suspecting the caps or transistors feeding the relays, but I also noticed a rather odd thing on the same board.

There's two sets of red wires which appear to have been jumpers of some sort over a rectangular hole in the board. However they look as if they've been cut in the middle for some reason :dunno: ??

I don't know what purpose they serve, but I think it very odd that they would be cut like this. It doesn't look like the dust had been disturbed for all it's 25 years of life, but ya never know...

Any help would be much appreciated...

Cheers

Dennis
 
Don’t sweat the jumpers they are suppose
to be that way. As for your relay the first
thing to check would be the ½ amp fuse on
the left side of the receiver and see if its bad.
It sits right beside the 4 amp main power fuse.
Bear in mind if the fuse is bad you could have
a component like a transistor, diode or cap that’s causing
it to blow. If the fuse is good check the voltage
going the relay it should be about 20 volts DC
to the coil. If there is no voltage then you need to
check some of the other components in circuit.
Also check for any cold solder joints on the boards.

This will give you a place to start. I am sure some of
the others will chime in also.

Hope this helps.
 
Many thanks - that gives me a good start. I was thinking of replacing the caps on that board as well, cuz they're around 25 years old and have been sitting in Bermuda's climate for all that time. Accessibility to that board is not going to be easy, but I can reach it from below, so I can desolder components if necessary.

Cheers
 
I have a 3700 that recently came in that’s
going to get the same treatment. All caps
are going to get replaced and rework the
solder joints. Something else you may want
to do while you have it apart is to regrease
the output transistors. After 25 years the heat
sink compound can start to harden and loose
some of its ability to transfer heat which can
lead to…....well you know.
 
Thanks Glen. I'm thinking I'll want to solder those wires bound to posts as I know that corrosion takes it's toll as well.

BTW, if you have a copy of the schematic for the 3700 in electronic format, would it be possible to get a copy from you?

Cheers
 
Back
Top Bottom