Fender Stage 112 SE pops when powering off

[weiss]

The volume is always turned almost down, even then it makes a massive pop when i turn the amp off.
Would there be any solution to this?

thanks!

 

[Bo Deadly]

Maybe an electrolytic capacitor is leaky from being exposed to high heat and one half of the supply is dropping somewhere (like for an op amp). Do a visual inspection of the power amp section and look for areas that are discolored where parts might be a little toasted.

Unfortunately from looking at the Fender Stage 112 SE Schematic, there are quite a few electrolytics in there. You could poke around with a meter first (if you're up to that sort of thing).

It doesn't help that the circuit looks a little odd with some kind of speaker feedback. Not even gonna try.

 

[12afael]

Make an amplifier to turn on and off silently usually require some  special circuit. Capacitors charge and discharge in different times producing the pop noise that is amplified through the circuit.

Sometimes the mute control is used if the power amp have one. Sometimes even the output is disconnected with a relay.

I see a mute circuit in the schematic but it can be just to momentary mute the amp while changing channels. Anyway I would check if that it is working.

 

[Gus]

Before you start changing parts and possibly causing other issues look carefully around the +- 16 VDC circuit.

Check the solder connections for R114 and R115 and the Zeners CR41 and CR42 and caps in that section.

Issues with the lower voltage +- supply and it use in switching and muting would make this something to check.

 

[Bo Deadly]

One thing to try would be to ground TP11 and then see if the pop persists. If it does, the issue is downstream from that point. If it doesn't, it's upstream.

 

[Tubetec]

Ive worked on a few of the Fender transistor amps over the years ,

A fatigued (thermally and physically )solder joint on one of the reservoir caps could be a possibillity , that can be tricky to spot sometimes , a difference in the resistance in series with each  cap on + and - sides could cause enough of an  asymetrical discharge you get a bang when you power down .
in some series of those amps  the legs  of the coupling caps were prone to vibrational fatiguing and failing that way .
also be sure to check the 'coffin' ceramic resistors for physical integrity and continuity.
I dont think I ever saw one of these amps that some young up and coming Jimi Hendrix managed to kill completely , but they do have more than their fair share of niggly oddball  problems ,a lot of which seem to be related to vibrations in the pcb . 
I think at some point in production they started schlonking  the 'usual suspect' components with  adhesive to keep them better stuck down  :-[    maybe a few small blocks of foam between pcb and chassis might help damp things a bit better.