Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Hi, new so forgive me if I've posted where I should have joined a discussion.

My Marshall VS65R had a problem where the switch [SS 160 3 by rongfeng] wouldn't click when pushed in / unit would power on - red light - then fade.
So I had a look and identified the switch, saw that half of its inner plastic had melted. Not switching correctly.

So I've found a replacement switch [difficult!] which arrived today.

Have taken out the circuit board with a view to installing the replacement and having had a look at it in some decent light can see some discoloured areas [pictures attached].

Nothing that's immediately obviously burned but as a relative newb to electronics I'm wondering if anyone else can have a look and advise if it's fried [probably] or go ahead with the replacement.

As stated it flares on then powers off. Holding the switch in doesn't make a difference.

Any help appreciated / please feel free to point me elsewhere in this forum if I've taken a wrong turn.

Pictures are both sides of the board where it's discoloured + the burnt switch.

Cheers!

Hi donjuames, A big welcome to you.
Yes the switch is obviously history so needs replacement.

Just remember this is Mains voltage ,,make sure the power cord is out of the wall socket before you proceed.

As to the darkened section on the board ,, it's fine.
Those two zener diodes run quite hot and the pcb will darken over time.

I've seen similar setups where the board is almost black but amp still working.
Ideally those zener diodes should be raised a bit higher off the pcb to reduce the heat transfer as it can often crack the solder joint over time.
Phil.