Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: J Rindt on March 27, 2018, 11:45:04 am

Title: fender deluxe 112 popping
Post by: J Rindt on March 27, 2018, 11:45:04 am

This amp makes a Loud pop when you shut it off. Not like the pop from a bad switch (though i did replace the switch). It sounds more like a part...maybe a Cap or Coil that has charged up. Is that possible.? It pops and then sounds like it drains down for a fraction, if you know what i mean.
Is there something i could do to fix this.?
Thank You

Title: Re: fender deluxe 112 popping
Post by: shooter on March 27, 2018, 01:30:00 pm

do you hear the pop from the headphone jack?
how about the preamp out?

got a meter that "stores" min/max values, or scope?  with a meter put the + on the +40, the - on the -40 taps and turn on/off, does the DC spike?
put the amp in a dark room, power up then off and look for sparkies from connectors, especially the transformer/rectifier area

sandbox stuff can be fun, working the gremlins from one now :think1:

Title: Re: fender deluxe 112 popping
Post by: Leevi on March 27, 2018, 02:03:34 pm

I have used in some cases the following component (PMR 209) that has eliminated the pop.
It should be connected across the power switch. Note that there will be a small leaking current through the component.



http://www.farnell.com/datasheets/1244264.pdf


/Leevi

Title: Re: fender deluxe 112 popping
Post by: J Rindt on March 27, 2018, 04:15:10 pm

Quote from: Leevi on March 27, 2018, 02:03:34 pm

I have used in some cases the following component (PMR 209) that has eliminated the pop.
It should be connected across the power switch. Note that there will be a small leaking current through the component.



http://www.farnell.com/datasheets/1244264.pdf (http://www.farnell.com/datasheets/1244264.pdf)


/Leevi

Keeping in mind i have just a basic knowledge of electronics.....this power switch, switches Both the Hot and Neutral. So i am just  2x checking.....This component would go across that.....not from some point to ground.?
Thank You

Title: Re: fender deluxe 112 popping
Post by: Leevi on March 27, 2018, 11:14:38 pm

In case of 1xON-OFF switch the component should be connected as in the picture.
If you are using 2xON-OFF switch you should probably add the component across the both switches or shortcut one of the two switches?
I have not used PMR209 with 2xON-OFF switches so I'm not sure how it would work there.




/Leevi

Title: Re: fender deluxe 112 popping
Post by: Leevi on March 27, 2018, 11:31:17 pm

You can first try the behavior by using a resistor and capacitor across the switch.
See the picture. I think in the final solution is better to use the PMR209 component since it is more robust and tested for that purpose.


/Leevi