On/Off Mod Switch/Pot Popping 66 Vibrolux Rev.

Max Collins · 05-13-2009, 04:58 PM

I replaced the tremolo intensity pot on my VR with an on/off pot-switch. This really woke up the old girl but it pops real loud when I click it back and forth. How can I stop this. I am not real technically minded. The way that I was able to do the mods I have to my amp was by very elementary descriptions so if you can dumb it way down for me I would be grateful. I'm looking at the chassis with the back facing me so if you could say solder a so and so resistor from _____ leg of the intensity pot to_____.
The mods I have done are: added midrange knob, soul control (thanks Smitty) and the tremolo bypass.
Thanks!

guitician · 05-13-2009, 05:05 PM

Is the on/off switch wired to the footswitch jack?

Max Collins · 05-13-2009, 05:12 PM

Quote:

Originally Posted by guitician

Is the on/off switch wired to the footswitch jack?

No Sir, I just substituted a pot with a click on/off switch in it. It is the intensity pot for the tremolo.

guitician · 05-13-2009, 06:19 PM

So, is the switch part of the pot being used for anything? If not, I dont see how it could be making a popping sound. That tremolo circuit is on the bias supply, so any breaks in the wipers contact with the resistive element would pop.

Max Collins · 05-13-2009, 09:47 PM

guitician · 05-13-2009, 11:26 PM

I see now. Your opening the line to the pot and putting the switch into it. I thought using the footswitch connection would work better, and accomplish the same thing, without pops. You could try a small ceramic disc cap(~.001uf) from either side of the switch, but if the intensity is left high, it may be audible.

loudthud · 05-14-2009, 05:06 PM

There are three capacitors feeding the node where the pot is connected and one of them probably has a little excess leakage that causes the node to 'float up' when the pot is disconnected. Probably best to have something like a 1Meg resistor to ground at all times on that node and replace all the capacitors. Connect the resistor to the switch terminal that goes back to the eyelet board and groound the other side at the pot.

Max Collins · 05-14-2009, 05:35 PM

Thank you for the replies. Loud thud: Just to confirm....the left lug goes to ground and the middle wire goes to the board so I remove the middle wire and put the resistor there connecting the wire to the other side of the resistor, yes?

05-13-2009, 04:58 PM	#1
Max Collins Junior Member Join Date: Feb 2009 Location: Houston, TX Posts: 7	On/Off Mod Switch/Pot Popping 66 Vibrolux Rev. I replaced the tremolo intensity pot on my VR with an on/off pot-switch. This really woke up the old girl but it pops real loud when I click it back and forth. How can I stop this. I am not real technically minded. The way that I was able to do the mods I have to my amp was by very elementary descriptions so if you can dumb it way down for me I would be grateful. I'm looking at the chassis with the back facing me so if you could say solder a so and so resistor from _____ leg of the intensity pot to_____. The mods I have done are: added midrange knob, soul control (thanks Smitty) and the tremolo bypass. Thanks!

05-14-2009, 05:06 PM	#7
loudthud Supporting Member Join Date: May 2006 Location: Texas USA Posts: 921	There are three capacitors feeding the node where the pot is connected and one of them probably has a little excess leakage that causes the node to 'float up' when the pot is disconnected. Probably best to have something like a 1Meg resistor to ground at all times on that node and replace all the capacitors. Connect the resistor to the switch terminal that goes back to the eyelet board and groound the other side at the pot. __________________ WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personel.

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05-13-2009, 05:05 PM	#2
guitician Senior Member Join Date: Aug 2008 Location: Phoenix Posts: 340	Is the on/off switch wired to the footswitch jack?

05-13-2009, 06:19 PM	#4
guitician Senior Member Join Date: Aug 2008 Location: Phoenix Posts: 340	So, is the switch part of the pot being used for anything? If not, I dont see how it could be making a popping sound. That tremolo circuit is on the bias supply, so any breaks in the wipers contact with the resistive element would pop.

05-13-2009, 09:47 PM	#5
Max Collins Junior Member Join Date: Feb 2009 Location: Houston, TX Posts: 7

05-13-2009, 11:26 PM	#6
guitician Senior Member Join Date: Aug 2008 Location: Phoenix Posts: 340	I see now. Your opening the line to the pot and putting the switch into it. I thought using the footswitch connection would work better, and accomplish the same thing, without pops. You could try a small ceramic disc cap(~.001uf) from either side of the switch, but if the intensity is left high, it may be audible.

05-14-2009, 05:35 PM	#8
Max Collins Junior Member Join Date: Feb 2009 Location: Houston, TX Posts: 7	Thank you for the replies. Loud thud: Just to confirm....the left lug goes to ground and the middle wire goes to the board so I remove the middle wire and put the resistor there connecting the wire to the other side of the resistor, yes?

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