Hot Potz II cleaning

[yeeshkul]

Did anyone try to clean the sealed HPII pot? It is a bit scratchy so i was thinking about drilling a hole from the side so i can spray the liquid in the body ... is that a good idea?

[Mark Hammer]

Pry the tabs, lift the back off and really clean the crap out of there with a cotton-tipped applicator.

Keep in mind that all pots, especially if used as much as a wah or volume pedal pot, generate their own dirt.  The wiper makes contact with the resistive strip by having pressure applied, which means friction, which means a very gradual micro-erosion of resistive strip particles and micro-deformation of the surface.  The analogy I like to use is that of a newly paved road that starts out velvety smooth, but over time develops little pot holes and cracks, with the rubble removed from the asphalt paving sitting atop the pavement.  When you drive over it, the "noise" you experience in the ride is a consequence of adapting to both the little dips and the little bumps from the rubble.  Keep in mind that the rubble sitting atop the pavement now also serves as a kind of abrasive material that your car rubs against the rest of the pavement, further damaging the surface.

With the back of the pot removed, you can use a Q-tip or similar, or simply wrap a bit of toilet paper around the end of a toothpick.  Dab it in a bit of the appropriate alcohol and wipe the surface of the strip clean. You should see some blackish gunk on the cotton/paper after you have wiped it.

This clears the "rubble" but does not address the cracks and dips resulting from that erosion.  It can be hard for some folks to get, but I use this wonderful stuff called Stabilant (www.stabilant.com) that provides a viscous, nondegrading conductive-polymer layer on the strip, functioning much like a liquid solder joint.  It is classified as a contact enhancer, not a cleaner. It certainly can't fix wah pots that are past the point of functionality, but can bring pots back from moderate scratchiness very nicely by plugging up those micro-gaps.

Your first productive step, however, is to clear the "rubble".  Spraying in some contact cleaner afterwards will not solve everything, but it won't hurt.

[yeeshkul]

Mark thanks! I was scared i would crack the isolation, but will do it the way you described above.

[Mark Hammer]

You're welcome.  My sense is that what is distinctive about wah pots is that:

a) They have much thicker and wider resistive strips to adapt to the constant wear and tear.  Of course this also means the potential for more "rubble" accumulating.  To the extent that the scraped-off resistive compound can turn around and act like an abrasive compound, I suppose it pays to take the pot apart now and then (every couple of years?) and do preventative cleaning, schpritzing in some contact cleaner in the intervening years.
b) They have broader wipers.  Take apart enough pots and you'll see that wiper can vary in how many "fingers" they have, as well as whether they "push" (like the cowcatcher on old-fashioned trains) or "drag".  The optimal for lowest noise and longest viable life is a wide dragging wiper.  More contact but less abrasive friction.
c) The have sturdier shafts and collets to cope with the pressure being applied via the gear mechanism.
d) They're sealed to restrict the dirt to only internally-generated crap.  As my prior note indicated, that doesn't make them dirt-free or noise free, just dirt-reduced and noise-reduced.

In theory, you could make a wah with a conventional 16mm Alpha pot, but it wouldn't last quite as long.

[Paul Marossy]

It is a bit scratchy so i was thinking about drilling a hole from the side so i can spray the liquid in the body ... is that a good idea?

It might work, but you'd have to spray quite a lot of contact cleaner inside of it, and it still may not do the job (speaking from experience with other pots). You also run the risk of damaging the pot's guts.

Pry the tabs, lift the back off and really clean the crap out of there with a cotton-tipped applicator.

That won't work if you have the newer plastic bodied ones. Taking it apart would pretty much ruin it. See pic:


It does work with a conventional metal bodied pot, though, I've done it before. Here's the process: http://www.diyguitarist.com/DIYStompboxes/CTS-PotRebuild.htm
It helps to use some rubbing alcohol on the Q-tip, you can really get 99.5% of the gunk out of there.

[Mark Hammer]

Duly noted.  I wasn't aware they now came in that form.  I only have a couple of the older metal-backing types.  Yep, no tabs, no pry. 

[Paul Marossy]

Duly noted.  I wasn't aware they now came in that form.  I only have a couple of the older metal-backing types.  Yep, no tabs, no pry. 

No problem. That's how the new ones are manufactured now. IIRC, they are supposed to last for one million operations according to Dunlop.

[Mark Hammer]

No problem. That's how the new ones are manufactured now. IIRC, they are supposed to last for one million operations according to Dunlop.

That's feasible, assuming the resistive strip is made of the "right" material (e.g., conductive plastic) and does not generate particles inside like the more traditional types.

[yeeshkul]

guys did you measure how the resistance runs in Hot Potz and ICAR taper? I made 2 identical wahs, one with the common ICAR taper and the other one with HotzPotz.
The ICAR seems to have shorter middle section - i mean it breaks the sound faster producing more prominent "wah". Hot Potz sounds smoother with warmer treble side. I personally prefer ICAR .

EDIT: Paul, nice photo-essay, thanks!

[Paul Marossy]

EDIT: Paul, nice photo-essay, thanks!

Thanks.