Need Help With Erratic Volume Control on Kapa Guitar

[Mike47]

I hope someone in this community can help me figure out what's going on with the volume controls on my electric guitar.

I recently replaced the volume/tone controls in a 60's Kapa Continental guitar. I replaced the volume pot with  a 'B' pot and the tone pots with 'A' pots. The old volume pot seemed to have a bad spot causing the volume to not react in a completely linear fashion. Several months ago I had to replace both pickup switches as they were not making good contact.

So I was surprised to hear the new volume control also not work as I expected. A small turn gives no volume, a slight further increase in the turn brings the volume to near full. Further rotating the pot does nothing to the volume. So most of the pot's resistance has no affect on volume.

Both pickups are working. My pickup test (beyond listening) is to switch the pickup on and touch the pickup adjustment screw with a metalic screwdriver. A loud noticeable 'pop' results when touched and none when the pickup is switched off. Tone controls seem to work but my hearing isn't what is used to be.

So...are the pickups (which are original) just not working well? Any other ideas as to testing or potential problem areas is greatly appreciated.

[mrbrown49]

You want a log taper pot for the volume.

[daddymack]

you may have reverse wired the pot....

[Mr.Grumpy]

On 12/17/2022 at 9:04 AM, Mike47 said:

A small turn gives no volume, a slight further increase in the turn brings the volume to near full. Further rotating the pot does nothing to the volume. So most of the pot's resistance has no affect on volume.

 

Sounds like you may have used the wrong resistance pots. Typically single coil pickups use 250 k Ohm pots, guitars with humbucking pickups use 500 k Ohm pots.  From what you're describing, it sounds like you used a pot with a much lower resistance than normal. 

 

On 12/17/2022 at 9:04 AM, Mike47 said:

Any other ideas as to testing

Buy a multimeter. They are cheap to buy and simple to use. 

Edited December 19, 2022 by Mr.Grumpy

[Mike47]

Thanks for replying. Old pots were 250k which is what the new pots are. I did check with a meter to ensure the replacement was a linear pot. Old pot worked same which is why I thought the pot was bad.  Guitar uses Hofner pickups.

[daddymack]

could you post some close up pics of the control cavity wiring?

[mrbrown49]

15 hours ago, Mike47 said:

Thanks for replying. Old pots were 250k which is what the new pots are. I did check with a meter to ensure the replacement was a linear pot. Old pot worked same which is why I thought the pot was bad.  Guitar uses Hofner pickups.

Linear?

Could be the problem.

[davie]

1 hour ago, mrbrown49 said:

Linear?

Could be the problem.

This.

Guitar pots use "audio" taper (aka log), not linear.

[Mike47]

On 12/20/2022 at 8:44 AM, daddymack said:

could you post some close up pics of the control cavity wiring?

Pics were hard to get a clear shot but I'll upload what I got. Maybe one of them will show you what you might be looking for. Obvious, volume pot is closest to the switches.

 

For those question my choice of a linear pot for volume, yes, it's usual to use a log pot. But a linear pot provides more even volume control. I doubt it has any impact upon the problem I'm experiencing. 

[mrbrown49]

1 hour ago, Mike47 said:

But a linear pot provides more even volume control. I doubt it has any impact upon the problem I'm experiencing