standby switch, whats up with the snap, crackle, pop?

jezzzz2003

Member
Messages
2,792
Hi .
I am wondering why my re-issue marshall 1987x pops sometimes when I switch on the standby switch>??
Whats up wid dat?:BITCH
 

number9

Member
Messages
40
I have seen several reasons for this... the main ones are:
Bad ground, or a ground that is faulty or not having a very good connection, really
check around the filter caps.
Bad filter cap, this is kind of rare (not the bad cap, the bad cap making that sound)
Bad power switch (I see this a lot more than I would like to... geez, is a good switch that much more?)
Bad wiring to the first cap... check all of those solder joints!
Arcing somewhere from inrush current... I have sometimes seen these elusive
"wire was slightly crimped/cut/whatever here, and now it starts to pop when cut on"

Most of the time I find the problem is a ground, or the switch.

Hope that helps some.
 

jezzzz2003

Member
Messages
2,792
number9 said:
I have seen several reasons for this... the main ones are:
Bad ground, or a ground that is faulty or not having a very good connection, really
check around the filter caps.
Bad filter cap, this is kind of rare (not the bad cap, the bad cap making that sound)
Bad power switch (I see this a lot more than I would like to... geez, is a good switch that much more?)
Bad wiring to the first cap... check all of those solder joints!
Arcing somewhere from inrush current... I have sometimes seen these elusive
"wire was slightly crimped/cut/whatever here, and now it starts to pop when cut on"

Most of the time I find the problem is a ground, or the switch.

Hope that helps some.
Cool, thanks for writing back!
I also would like to know if any of theser symptoms can hurt my amplifier?
 

Fuchsaudio

Member
Messages
7,755
jezzzz2003 said:
Cool, thanks for writing back!
I also would like to know if any of theser symptoms can hurt my amplifier?
Have your amp tech (or if you DIY) add a .02 @ 600 V cap across the switch terminals. It makes a nice suppressor for sparks and arcs that make noise and kill switches prematurely.

Many, if not all, of these standby switches are rated for a lower voltage and a higher current (old Fender's are really bad culprits for switch under-rating) and the caps make them survive the arc better when used at DC. I guess the Engineer's figured higher voltage and lower current would be okay...
 

jezzzz2003

Member
Messages
2,792
Thanks for your replies guys.
I have had the tubes replaced and thats not the problem,
I checked all earth connections so I think I might go with the cap and see what happens,
Good to know it will be o.k without though.
I have also noticed old fenders with the same problem but even louder than my amp.
Thanks again.
 

Lammy

Member
Messages
480
Just got a traynor yba-1 back from a recap retube, and its doing this also. Its freaking me out! I am about to go on tour for 3 weeks, so I dont have time to drop it back off to have him check it out. It wont cause any damage to speakers or the amp?
 

jezzzz2003

Member
Messages
2,792
It will not cause any damage to your tubes or speakers as the voltage is only very slight as I have learned since.
I just dont worry about this anymore and have never had a problem in a year of fairly heavy usage.
Although I do know how it is to stress night and day over little problems like this.
Try to sleep well at night and dont worry about it.
Cheers!!
 

Lammy

Member
Messages
480
Thanks! Used it on a gig last night, and there actually was no snap crackle or pop.
 

Matt117

Member
Messages
634
Have your amp tech (or if you DIY) add a .02 @ 600 V cap across the switch terminals. It makes a nice suppressor for sparks and arcs that make noise and kill switches prematurely.

Many, if not all, of these standby switches are rated for a lower voltage and a higher current (old Fender's are really bad culprits for switch under-rating) and the caps make them survive the arc better when used at DC. I guess the Engineer's figured higher voltage and lower current would be okay...
Hey I just saw this old post of yours about adding a .02pf? 600v cap across lugs of the power switch on amps that crackle and pop when starting up.

I know its not one of your amps.. but a Mesa boogie lonestar classic that I have.

It crackles and pops like pop corn or fireworks for 30-60seconds after taken off standby and set to run. Nothing plugged in, everything set to 0 or 10 makes no difference.

I've cleaned the tube sockets, tube pins, measured the resistors around the power tubes.

It seems to be once that current it all allowed to flow through the amp it can't handle it or something? Guitar signal is very minimal while popping is happening (its that loud).

I've tried new tubes. Still persists.

I love tinkering, but do not know a lot. I do have a cap draining resistor from weber, so I know how to discharge an amp and check its safe to poke around in. I would take it to a tech, but I do not know of any here in the Dominican Republic (moved here in July -- going to be here for 3 years), so I'd love to figure it out myself.

Wondering if you'd be willing to offer any advice or directions? I emailed mesa and they said it has to be tubes.. but I already tried that a few times.

Thanks
 

zenas

Member
Messages
8,697
@Matt117 since it makes noise that long after the switch is thrown I'm wondering if it's something else? I'd probably hook a volt meter up to the "off" side of the switch and see if there's any fluctuation there, before swapping it out. Could be something else that's unstable till it warms up a little.
 

TimDude88

Member
Messages
191
I have a question about this. My amp makes a pop only when the standby switch is going from on (sound) to off (no sound). It's one single pop. Sweetwater has an article on this, but I figured I would post the question here. They said to simply power down the amp WITHOUT using the standby. They say this is healthy, arguably healthier, but I figured I would ask for people's opinions here too. Is this a healthy thing to do if this is my only issue with the popping standby?
 

zenas

Member
Messages
8,697
No need to use standby mode to shut an amp down. Some folks say it gives the tubes a "cool down period", in standby the tube's heaters are on. Don't know about other folks but normally if you want to cool down anything, you shut off the heater.

Actually the way I fixed the standby pop on one of my Twin Reverbs was easy. I don't use the damned thing! Flip both switches at the same time, off/on on/off. Don't remember which one actually does it now, been using both like that for years. Hasn't hurt a damned thing, and won't.
Why fix something you don't need in the first place?

And please no Gerald Weber book references in the ensuing argument. :)
 

Matt117

Member
Messages
634
@Matt117 since it makes noise that long after the switch is thrown I'm wondering if it's something else? I'd probably hook a volt meter up to the "off" side of the switch and see if there's any fluctuation there, before swapping it out. Could be something else that's unstable till it warms up a little.
Yeah I wondered about tube sockets as if the connects completes better once the amp
Warms up. Visually the filter caps are good. I’ll have to check them out with the meter.
 

teemuk

Member
Messages
3,156
The switch may have simply been worn out and no longer works properly. Wouldn't be the first stand-by switch with that symptom.

Basically, each time you switch a mechanic switch it's contacts will bounce somewhat. When a stand-by switch switches a high tension voltage of power supply it also generates a giant current surge in that high voltage potential. Switch contacts arc and melt, and when "bouncing" they do it repeatedly, and each time the contacts wear out a bit mechanically.

Your switch is also probably rated for 120 volts AC and not even suited to reliably switch about 400 - 500 volts of DC! (Switches actually suited for this are HUGE, you will not find one from amp's front panel largely because it wouldn't even fit there). So failure is evident. It will not fail immediately but will surely wear out much faster than in applications its actually rated for. While wearing out it may switch alright and otherwise seem to function normally, but bouncing gets worse, contact is not as solid, contacts are "pitted" with carbon residue, switching gets noisier, etc.

The capacitor across the contacts can help somewhat but its just a bandaid for a very bad design.

The inrush surge will also stress power supply components, like those capacitors some people claim the stand-by switch protects.

No. Breaking the HT supply protects nothing! It is a poor design for simple muting circuit with lots of undeserved hype. Period.

There are stand-by switching schemes that can actually extend tube life, provide a "soft start" without surge transients and warm up noise, which do not "pop", and which do not stress the switch itself nor other components. Switch that disrupts the HT supply is not one. It's just a poor excuse of a feature.
 
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