Stanby switch loud "pop"

[Latole]

Hello ,
I put all my vintage amps in order. Replacement of filters caps, bias cap, bypass caps, 3 progs cable, bias  etc.

I finished my Bandmaster AB763, the only thing I block and the very loud "pop" with the Stanby switch. I did all the known mods *; a resistance across the switch, a 0.047 capacitor and even a new switch. No success 

All mods* that works on my other amps .... except the Bandmaster.
Why ? And what to do ?

https://robrobinette.com/Generic_Tube_Amp_Mods.htm#Pop_Reduction   (fixed link... sluckey)

Thank's if you can help me

[pdf64]

What value resistor, ie the 47k suggested by Merlin http://www.valvewizard.co.uk/standby.html
If it's still popping with that, then it's followed by a couple of alternatives.

[Latole]

Thank's. I'll try these from Merlin and report ;

 A 47k 2W device is a reasonable compromise. You can also add a 100nF (or so) capacitor across the switch to reduce arcing inside it. It is hard to find (attractive) switches which are rated for high voltage use, especially DC voltage, so most people just use a suitably heavy-duty mains switch. Since the HT current is quite small (hundreds of milliamps, not amps), this does not seem to be a problem.

_________________________________

I don't want to put a bigger/ most powerful switch which need a bigger hole

[Latole]

I have tried Merin / wizzard's suggestions without success. 47 K  and  0.1 mfd cap. Always the "pop".
These are just about the same suggestions as Robrobinette

[HotBluePlates]

I have tried Merin / wizzard's suggestions without success. ... Always the "pop". ...

On another forum, there are at least 30 threads that are 15 pages long each, bickering about Standby switches.  The best choice is don't use one and if it's already present on your vintage Fender, just leave it in Play mode.

[Latole]

I have tried Merin / wizzard's suggestions without success. ... Always the "pop". ...

On another forum, there are at least 30 threads that are 15 pages long each, bickering about Standby switches.  The best choice is don't use one and if it's already present on your vintage Fender, just leave it in Play mode.

AhAh no, it is too easy to give up

My question was ; All mods* that works on my other amps .... except the Bandmaster.
Why ?

Work on other Fender too.

[sluckey]

Hi-rez pics, especially STBY switch.

[pdf64]

I have tried Merin / wizzard's suggestions without success. 47 K  and  0.1 mfd cap. Always the "pop".

Including the last 2, ie removing dc from the switch?
Does the pop occur when switching from play to standby, from standby to play, or both?

[Latole]

I have tried Merin / wizzard's suggestions without success. 47 K  and  0.1 mfd cap. Always the "pop".

Including the last 2, ie removing dc from the switch?
Does the pop occur when switching from play to standby, from standby to play, or both?

" Including the last 2, ie removing dc from the switch? "

No, I don't want to mod amp wirings
Pop : only from Standby to play , never from Play to Standby

[pdf64]

So it won’t be back emf from the choke, hence the 47k not helping.

How about if the tube in the phase splitter circuit is removed?

[Latole]

With PI tube removed Pop is more quiet

And any more Pop if I switch stanby on/ off fews times..

With PI in, always loud pop

What did it mean ?

[Colas LeGrippa]

Swap the switch it migjt work.

[Latole]

Swap the switch it migjt work.

Read my top message ; ..... even a new switch. No success

[pdf64]

With PI tube removed Pop is more quiet

And any more Pop if I switch stanby on/ off fews times..

With PI in, always loud pop

What did it mean ?

Other than that standby is a stupid concept, I’m not sure 
How about if the power tubes are removed?

[Latole]

How about if the power tubes are removed?

Why not going to the best solution ; unplug speaker

[DummyLoad]

doesn't matter who's method you use: you're kicking in a substantial inductive load that's connected to the speaker, stuff is gonna go pop. maybe not bang pop! but will have at least a low pop or subtle thump - but it's gonna make noise. deal with it! hi-fi stuff has a time delay relay for addressing turn-on thump, but with tube-amps we don't want infinity load.   

if you want something less dramatic, then consider a mute switch on the PI input or if SE, the final preamp? 


--pete

[Latole]

doesn't matter who's method you use: you're kicking in a substantial inductive load that's connected to the speaker, stuff is gonna go pop. maybe not bang pop! but will have at least a low pop or subtle thump - but it's gonna make noise. deal with it! hi-fi stuff has a time delay relay for addressing turn-on thump, but with tube-amps we don't want infinity load.   

if you want something less dramatic, then consider a mute switch on the PI input or if SE, the final preamp? 


--pete

 
All mods* that works on my other amps .... except the Bandmaster.
Why ?

I don't want to mod a vintage amp.

Thank you all, amp will stay like that

[sluckey]

Which switch are you using? Post a pic.

[Leevi]

I have used this component succesfully to remove power switch pops. Standby switch works with DC but try to serial connect cap and resistor across the switch.


https://datasheetspdf.com/mobile-datasheet/PMR209.html



/Leevi

[Latole]

Which switch are you using? Post a pic.

I have a lots of good switches, many brands, some original for Fender. some more powerfull ( too big to fit anyway)  none work.

I often fix this issue on many amps with new switch and / or capacitor only, with success. 

Thank you.

[Latole]

I have used this component succesfully to remove power switch pops. Standby switch works with DC but try to serial connect cap and resistor across the switch.


https://datasheetspdf.com/mobile-datasheet/PMR209.html



/Leevi

Did you test it on a Bandmaster ?

[Leevi]

No, what is special with Bandmaster (what circuit)?
/Leevi

[Latole]

No, what is special with Bandmaster (what circuit)?
/Leevi

I gave all this information when opening the post : AB763

[Latole]

Thanks everyone for trying to help me.
I reassembled the chassis in its case. I leave as is.

[sluckey]

I don't have any objectional pop with my '67 AB763 Bandmaster. I wonder if there's something wrong with the original rectifier board? Maybe try this...

Disconnect HT leads and B+ wire from rectifier board. Connect these three wires to a temporary rectifier that is floating in air. Any joy?

[Leevi]

OK, Bandmaster circuit (AB763) as such is not the root cause for the pop. There must be some other issues causing it.
Have you tried the PMR209?


/Leevi

[Latole]

OK, Bandmaster circuit (AB763) as such is not the root cause for the pop. There must be some other issues causing it.
Have you tried the PMR209?


/Leevi

No.

[Latole]

I don't have any objectional pop with my '67 AB763 Bandmaster. I wonder if there's something wrong with the original rectifier board? Maybe try this...

Disconnect HT leads and B+ wire from rectifier board. Connect these three wires to a temporary rectifier that is floating in air. Any joy?

  I'll try. 

My B+ read at least 425 volts if I remember, with no ripple. If something wrong with rectifier I should read low B+ no ?

[sluckey]

My B+ read at least 425 volts if I remember, with no ripple. If something wrong with rectifier I should read low B+ no ?

It's normal to have about 5 to 10V ripple at the output of the rectifier. My idea is that the original board may be conductive and causing problems. I don't really suspect the diodes, but my suggestion would eliminate the diodes and the board as possible culprits. May be a solution. May be a waste of 5 minutes. But at least you'll know. 

This is just a wild ass guess but it's easy enough to try. Maybe a bit more difficult since you have put the chassis back in the head. I hate putting that last nut on the chassis screw that's behind the PT.

[Leevi]

I hate putting that last nut on the chassis screw that's behind the PT.

Sounds so familiar😁


/Leevi

[AmberB]

That last nut is really fun on a late 60s silverface 50 watt Bassman...

[Latole]

I don't have any objectional pop with my '67 AB763 Bandmaster. I wonder if there's something wrong with the original rectifier board? Maybe try this...

Disconnect HT leads and B+ wire from rectifier board. Connect these three wires to a temporary rectifier that is floating in air. Any joy?

Same loud pop !

Try another switch, I have a lot of them, different brand ; same pop

[kagliostro]

+ 1 for Leevi's suggestion

it is'nt an expensive component

so give a try to a PMR209.pdf

Franco

[Latole]

+ 1 for Leevi's suggestion

it is'nt an expensive component

so give a try to a PMR209.pdf

Franco

 It 's  metallized paper with integrated resistor • 0.047 – 0.47 μF, 22 – 470 Ω,

I built something like that as suggested before with Robrobinette link