Peavey tnt130

[catalin gramada]

Hello. Tested old tnt 130 from Peavey I wanna pick for myself yesterday. It is full functional but when put power switch off after few seconds it emitted a short buzzy whizz. What can be the problem ,please? Thanks

[J M Fahey]

Not a real *problem* , just a small annoyance.

Many Op Amps become stupid when fed very low voltage (me too when I´m hungry) and some oscillate.

When you turn amp off voltages take some seconds to decay and go through that "stupid zone" ; since power amp still works (sort of) with those low (and decaying) rails you can hear the farty whine.

Most modern amps have a mute connected to power rails, so under, say, +/-8V or so amp is muted; if you are VERY annoyed, you can copy some mute circuit and add it there.

Personally, I wouldn´t worry, and call it a "feature"

[Jazz P Bass]

I have seen that issue before and it turned out to be a bad filter capacitor.

With the amp on, monitor the two power rails & look for excess ripple of the voltage.

The one I had was only one of the caps.

I replace them both once I knew there was a bad one.

[catalin gramada]

Thank You very much for your advices. Warm Regards. Catalin