Changing a Pot

[Naga]

the knob on my presonus HP4 is getting a bit lose, is there any hope for changing it?

 

[nikongod]

the knob? tighten teh set-screw.

 

[Naga]

nah, the actual mechanism

 

[mono]

Pictures might help for the majority who have no concept of exactly what the board and pot are like, but generically speaking:

Pot on wires- simply snip the wires or desolder them.

Pot on PCB- Use a desolder pump (plus soldering iron) to remove as much solder as possible. Then if there's still some pins held down by remaining solder, take forcepts or good/tiny needle-nose pliers to grasp the pot pin at the tip, and slightly wiggle it while reheating the solder, so that when solder hardens the continually-wiggled pot pin is still free of solder bond. It makes more sense while doing it than to describe and should be done gently but quickly (briefly heated) to minimize chance of pulling up circuitboard pads/tracks.

Then of course you need another pot with similar pin arrangement. In some cases I've successfully opened pots, bent their tension springs out a bit. Other times the spring is the electrical contact itself and can also be carefully bent outward. These are not optimal solutions compared to buying the right pot to replace it, but can work ok.

 

[Naga]

silly question: do pots have ratings, specifications?

 

[nikongod]

Quote:

Originally Posted by Naga silly question: do pots have ratings, specifications?

yes, and yes.

ratings with regards to power handling (1/8W, 1/4W, 1W, etc)

spec with regards to "linearity" (or how truly logarithmic they are for audio...) chanel matching, and the like.

 

[cire]

they also have a rating for the maximum amount of resistance they can give. for example, a 50k pot (also called trimmer) can give 0ohms all the way up to 50k ohms. theres also the amount of times they can be turned rating

 

[Naga]

any brand recommendations?

ill open the thing up and get some pics in the coming week

 

[mono]

Brand may have a lot to do with what you need, and what you can find. Note the pin arrangement and spacing, shaft length, shaft diameter, and mounting diameter. Note also that there is a difference between 6mm and 1/4" shaft, that while they're close, close isn't always enough - it needs to fit the knob else you have to find a different knob too. Essentially, measure every possible parameter including the resistance.