odd turn off noise - Fender Princeton Chorus - links to Youtube

[Kenrod]

What might I look into for correcting this issue?

[Jazz P Bass]

It sounds like the power supply winding down.
Possibly a bad power supply ripple filter capacitor.
You can check the ripple of each supply with a meter set to read volts/ac.

Does it make that noise with the guitar volume turned all the way down?
With nothing plugged into the input jack?

[Kenrod]

There was nothing plugged in when I turned it off, cable was just hanging halfway out of the input jack, nothing connected to the other end.

[Kenrod]

It sounds like the power supply winding down.
Possibly a bad power supply ripple filter capacitor.
You can check the ripple of each supply with a meter set to read volts/ac.

and this is because i should only find DC (rectified AC) under normal conditions, correct?

[Jazz P Bass]

There was nothing plugged in when I turned it off, cable was just hanging halfway out of the input jack, nothing connected to the other end.

Well that's not fair.
Unplug it.

[Jazz P Bass]

and this is because i should only find DC (rectified AC) under normal conditions, correct?

The filter caps remove the ripple from the rectifiers, as much as they can.
Figure roughly 30 mv's ripple is good.

[J M Fahey]

That's normal.

You do not have a problem.

Many amps do that, including many respected Gallien Krueger.

[Jazz P Bass]

Well, the audio shows a click (switch action) & a dropping bzzzz.
I have seen that bzzzz caused by failing power supply caps.
Usually just one rail.
Can't hurt to test the supply.

[überfuzz]

Does it 'act out' anything while you use it, play it? It seems very nice and quite. I wouldn't worry about it, if you do worry, check the filter voltages, i.e. AC ripple.

[g1]

Try it with the cord unplugged from the amp to see if it is still there.

[Kenrod]

That's normal.

You do not have a problem.

Many amps do that, including many respected Gallien Krueger.

It may be common, but i find it hard to believe it's normal.

Well, the audio shows a click (switch action) & a dropping bzzzz.
I have seen that bzzzz caused by failing power supply caps.
Usually just one rail.
Can't hurt to test the supply.

I'll crack it open and test when I have a chance. The start of this week has been busy. I hope to get into it Wed or Thur.

[g1]

It may be common, but i find it hard to believe it's normal.

It's normal if you have a cord plugged in with nothing connected at the other end. People don't normally do that.
Or if it is doing it with nothing plugged in to the amp input, please let us know that.

[Kenrod]

The cable was barely hanging in the jack, wasn't inserted.

[Kenrod]

I haven't gotten into this one yet(my sons spare amp) as I've been tinkering on other amps, but I did notice this. The turn off noise is louder with something inserted in the input jack versus nothing inserted. It still there with nothing inserted, just only about as half as loud.

[52 Bill]

I haven't gotten into this one yet(my sons spare amp) as I've been tinkering on other amps, but I did notice this. The turn off noise is louder with something inserted in the input jack versus nothing inserted. It still there with nothing inserted, just only about as half as loud.

If that's the case, it may have something to do with the turn on mute not working correctly. Check to see if there is an fet mute at the power amp input.