Checking DC resistance on your potentiometers
and
How to make your own "No Load" tone pot

by John Spina

Tools needed:
Small diagonal cutting pliers
  Nail polish (optional)
  Razor blade or Exacto knife
  Pliers
  Small slotted screwdriver
  Multimeter to read 250k and above in ohms
 
Purpose of this Tutorial
1 Being able to know the total pot resistance readings prior to installing a new or replacement pot into a circuit... We're talking specifically guitar here.. Higher pot resistance readings allow you to tweak more highs into your guitar and what the pickups see.. A 500k pot is going to make the guitar brighter compared to a 250k... This mod is more noticeable with the 250k pot values than it is with 500k or 1meg but works and achieves the same effect in all cases.. This mod was first seen on the Fender Delta Tone controls on the American Series replacing the TBX Tone control... I personally don't care for the TBX control and favor this mod instead..
 
2 The No Load tone pot when on 10,removes the load of the pot and the cap.. Once you put your tone control on or around the "9" position, you now return to a normal working tone control... This is a cool mod because you not only gain more high end, but you also get a bit more rawness of tone and slightly more perceived output... The guitar circuit absolutely has no negative drawbacks to having this tone pot in place... On a Strat you can use these pots in both positions..
Here's how you hook up your ohmmeter to check the total resistance of your pot.
Here's how to make a No Load Tone Pot
This shows the pot prior to be disassembled...
This shows the 4 little bent over retainers being lifted up so we can get the pot apart.
There are 2 types of pots shown in these pictures...
I'm calling type 1 the pot that has the carbon wafer and all electrical components all together
Type 2 is a CTS pot and the wafer can be totally separated from the other components for ease of the mod
I prefer the CTS pots in all of my guitar projects.. Notice type 1 only has the cover as it's only separated part,yet the CTS has multiple parts.. Be sure you remember how the CTS or this style pot goes back together!
 
Once you get the pot apart,and have the terminals facing up and away from you, notice the 1/8" area at the right terminal carbon area that we remove the carbon.

We are creating an open circuit between that right terminal and the carbon to create an open when your tone pot is on 10... You can either scrape or use nail polish... I always scrape because it's permanent.

I'm using white paint in the pictures to show the removal areas on both pot types.

Use a sharp razor blade,exacto knife etc. and remove the carbon in the areas shown in the pictures.
Optional... Would be to coat that area with nail polish.

Hook up your meter like the picture shows and be sure you have an open or infinite reading between both outside terminals of the pot...

If you do, you've succeeded in getting the No Load Pot created up to this point.

Next... Keep one side of your ohmmeter on the left outside terminal and put the other meter lead just below the area that you scraped... You want the lead actually on the carbon below the scraped area... You now should have a reading close to what the pot is rated at in resistance... A 250k pot can read plus or minus 20% either way... I Like my pots to read at least 250k or above and 500k or above.
Here's another cool trick to bring the resistance values up a bit if you're close.... Carefully take your exacto knife or razor blade and remove some carbon from the inside areas of both the top and bottom areas of the carbon... You aren't scraping the top of the carbon, but the thin sides of the carbon away from the area where the pot connection touches the carbon track...

Put the pot back together....
Take some final readings now with the pot all reassembled...
With the pot shaft facing you and the terminals facing up...
Connect one lead to the center terminal and the other lead to the right terminal...
With the pot turned all the way "clockwise" you should have an open or no readings...

Now if you turn the pot "counterclockwise" to the 9 position or below, the pot works like normal and you should see readings close to the pot values and a decrease now as you roll towards 0.
 
That's it... Pretty easy mod with very cool results....

 

 


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