!!Hum from Tone Pot 5e3 Build!!

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Stovemananon
Posts: 27
Joined: Sat Apr 09, 2022 12:51 am
Location: Greenville SC

!!Hum from Tone Pot 5e3 Build!!

Post by Stovemananon »

Hello all! I just completed my first 5e3 and it sounds tremendous. However, I have some hum and have isolated it down to the tone pot.

As you know, the only connection to ground through the ground lug of the tone pot is through the 472j cap. When I put an alligator clip on this lug and put it directly to ground, the hum stops. of course, this turns my tone pot into a volume pot which is not desirable :).

However, the amp still sounds great (minimal hum) and all volume controls work and the guitar comes through fine.

Any ideas on how I would get rid of this hum? Could it be the cap or the pot itself?

Note: I have checked to ensure the solder joint of the tone cap to ground is not cold. I did this by connecting an grounded alligator clip to the right side of the cap (the leg of the cap soldered to the back of the tone pot). There is no change in hum.

Thanks for any input you can provide!
Stevem
Posts: 5144
Joined: Fri Jan 24, 2014 3:01 pm
Location: 1/3rd the way out one of the arms of the Milkyway.

Re: !!Hum from Tone Pot 5e3 Build!!

Post by Stevem »

Try landing that needed ground back at the input jack, or maybe better yet to where that first 12ay7s cathode cap and resistor grabs there ground.

Trying them both is what I would do.

Also does the body of that pot test shorted to the chassis as it should?

Also make sure that tone cap is no where near any heater wires!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Stovemananon
Posts: 27
Joined: Sat Apr 09, 2022 12:51 am
Location: Greenville SC

Re: !!Hum from Tone Pot 5e3 Build!!

Post by Stovemananon »

I really appreciate the advice, I'll give that a try and will post back

One note about the ground to bypass cap and cathode resistor: this will be the chassis frame. So I would be grounding to the frame which will kill the hum, but not allow the tone capacitor to work (tone knob becomes a volume knob essentially).

Now to think of it, the jack is too, so this will cause my tone knob to act as a volume knob as the ground pot on the tone knob is now connected to the frame instead of the tone cap. Am I thinking right?

I will def check on the heater wires,

Again thanks for the input. I will try all this just in case I am missing something!
Stevem
Posts: 5144
Joined: Fri Jan 24, 2014 3:01 pm
Location: 1/3rd the way out one of the arms of the Milkyway.

Re: !!Hum from Tone Pot 5e3 Build!!

Post by Stevem »

Ground the end of the tone cap to either of those two locations.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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