9090DB Bump Into Protection

[ivandezande]

Here’s a new one.
Just fully restored this guy, but:
If you physically bump it, or turn a selector knob etc, the right channel meter will spike and the unit will go into protection for a second.
It’s in the preamp. No such behavior when the jumpers are pulled.
Is a BA312 going bad??? Very confused.

 

[Hyperion]

Is a BA312 going bad??? Very confused.

Dry joint or faulty connection somewhere.

 

[MIJ_Pioneer]

Start nudging components on the tone board. See if any are loose, particularly resistors. Reminds me of my 1250 where I fat fingered a resistor loose from holding the board.

If all else fails recap the power supply with silmic II and FG caps haha jkjk

 

[ivandezande]

The poking will commence tomorrow. Was expecting just channel dropouts, not a big ol surge.

 

[Skywatcher]

The poking will commence tomorrow. Was expecting just channel dropouts, not a big ol surge.

A loose ground, possibly a wire so close to another it only touches when "bumped" and possibly frayed from flexing, or a bad solder joint. Get some extra "eyeballs" and a dental mirror to have a close look before taking anything apart again. Once apart, you might not "notice" something will be close to touching when together. I have confidence you'll find the gremlin...

 

[LBPete]

To keep within the Sansui tradition, use a wooden chop stick to flex each board. Start with the protection board.

- Pete