Kill popping during shutoff of SS Marshall 5010

[aaron]

Hi everyone, I went to this page https://www.ssguitar.com/index.php?topic=2439.msg19970#quickreply_anchor
It's the same problem as mine.

and, based on the advice there, I installed this:


Here's the schematic:


So, the only thing that happened was that the "fix" gave me a on/off switch bypass....now the amp is always on....(double pole switch).

Any solutions?

thanks!

[Helmholtz]

The snubber schematic looks ok (you need the snubber twice).

You must have made a wiring mistake.
Best post a picture of the switch showing the snubbers.

[The Dude]

Yes, snubber twice. Or, you could bypass the neutral switching and switch only the hot side. It's not really necessary to switch both hot and neutral. Then, only one snubber circuit would be necessary.

[Helmholtz]

Yes, snubber twice. Or, you could bypass the neutral switching and switch only the hot side. It's not really necessary to switch both hot and neutral. Then, only one snubber circuit would be necessary.

Switching both sides might be a safety requirement in countries where the mains plug is reversible.

[aaron]

It's a very tight spot, I'll try to get a pic.
Yes, I put the exact same snubber on both sides.
Does the order of the resistor-capacitor make a difference?
thanks!

P.S. Could there be another cause for the pop at shutdown of the amp?

[Mick Bailey]

A different amp, but here's another take on the subject; https://music-electronics-forum.com/...ump#post787111

[Helmholtz]

....now the amp is always on...

Does that mean you can't switch off the amp now?
If so you've shorted something meaning a safety issue.
The order of resistor-cap doesn't matter.

I would try the method proposed by Mick Bailey.

[aaron]

This is how I wired it, and got the problem from the first post.

Here's a pic to demonstrate what I've done, taken out of the amp for clarity.
"Up" in the pic refers to how the switch would sit in the amp, and the off position.
"From Mains" refers to the Line and Neutral wires directly from the wall. They connect to the terminals on the bottom of the switch.
The wires to the PT reside on the top two terminals.
For no reason, the resistors connect to the terminals to the PT, and one of the cap leads connect to the mains terminals.

So, if you were to split the switch vertically, you would have the same cap/resitor on the Neutral line side of the switch.
Again, I left off the Neutral side wiring and the LIne side wire to the PT for clarity.

thanks!

[aaron]

Does that mean you can't switch off the amp now? Correct
If so you've shorted something meaning a safety issue.
The order of resistor-cap doesn't matter. OK

I would try the method proposed by Mick Bailey. Would I wire it as I photographed above?

Thanks!

[aaron]

Another view:

[Helmholtz]

First of all make sure the switch is still good.

If you're not a trained technician better take the amp to a pro.
Otherwise be extremely careful with any wiring on the mains side.

According to Mick Bailey's method the X2 cap is to be wired across the PT primary.
Looking at the schematic this means wired like the circle symbol (maybe a pilot lamp?) after the switch.

[g1]

Remove what you did and rewire as it was, see if the switch still works. Or check with a meter. I would guess the switch has arced closed and no longer works right.

[Tassieviking]

These switches can get stuck if you put too much heat into the terminals with a soldering iron.
if you had the switch in the closed position when you were soldering and applied too much heat or heated for too long the plastic could melt inside the switch and fuse it in the on position.
I learnt that lesson the hard way many decades ago, I always use crimp lugs on my projects because of this.

I am wondering if this is something new that this amp is making a popping noise, or has it always done this ?
Some amps just pop even when they were new back in the 80's, it might just be a common problem with this model.
If it has just started lately then why try to make modifications to fix it ?
The best way would be to find the fault that is making this happen, it might be a capacitor that is on its way out, or something else.
Does your amp have JMP27A written on the PCB ? There were several different circuits and different PCB's for the 5010 amp.

Here is the Marshall 5010 schematic with 78-2 marked on the PCB that I helped PinkJimiPhoton trace for his amp.
Marshall 5010 78-2 PCB Schematic Complete .pdf

[Jazz P Bass]

Yup.
I have had them melt myself.

[aaron]

Hi, so I removed my anti-popping caps/resistors, returned the switch to the amp in it's original configuration, and the switch works fine.
The popping is still there..... I can't speak about the amp's history, b/c when I got it, it came with a bad Bass pot that I had to fix.
So, after the fix, I was able to play the amp, and then noticed the pop when turned off.

BTW, if this is a clue, the pop occurs a second AFTER I turn off the amp.

Thanks, Tassieviking for the schematic!
Yes, mine is the 798-2 PCB.
My circuit board is not exactly as your schematic (my board doesn't have the 2 fuses after the transfomer), but other values of some resistors and caps match better with your schematic.

At this point, I don't know what to do.

From a theoretical POV, I'm very curious as to why my snubber circuit that I added not only didn't work, but also served to bypass the on/off switch...

I'll probably start a new thread, but when the presence, and preamp are turned up all the way, I get a high pitched squeal....If you happen to know why, let me know!
Thanks!