Pioneer A400 Volume Control

[robshebob]

My trusty old A400 has a noticeable crackle when you turn the volume knob up or down. Is this a fixable fault or is it Just old age?

Cheers

Rob

 

[cheechy]

Lol mine does the same. I think it is just old age.

It may be dust but I've never been brave enough to open her up and stick a dust spray in there.

 

[clockworks]

Switch the amp off, and turn the knob rapidly from one extreme to the other, several times.
The cause of the crackling is debris on the tracks of the potentiometer. Rapid, repeated, movement usually cleans it off.

If this fails, you can try spraying a small amount of isopropyl alcohol into the potentiometer, and repeating the knob-twirling.

If it still doesn't work, you need a new pot.

 

[cheechy]

Nice one I knew someone would know how these things worked

 

[robshebob]

Cheers Clockwork, do you need top open the amp up to do this or can you do it from the front panel (with the isopropyl alcohol)?

Cheers

Rob

 

[clockworks]

I suppose that you could do it from the front, but you'd need to be careful. Isopropyl alcohol can soften paint, so it might damage the fascia or the lettering.
If you want to try it, stand the amp on it's back, remove the knob, and trickle some isopropyl down the shaft. With a bit of luck, some will find its way inside. If the pot is a dual gang jobbie, getting isopropyl into the rearmost can might be tricky.

I'd remove the cover, and give the pot a good soaking.