Post by karl on May 25, 2009 2:34:02 GMT -5
Rebuilding Rotary Potentiometers:
Never been a big fan of contact cleaner that contains lubricant in it. It will eventually gather all kinds of dust and dirt and create a bigger problem. A better solution is to carefully take the potentiometer apart and clean it.
There are usually little metal tabs which can be bent up
(with a needle nose pliers) and the faceplate can be removed.
Inside you will find a circuit board with a resistive coating on it. A potentiometer works by dragging metal contacts along the surface of the coating. There are hundreds of variations on how this is done , but most of the time a ring is secured to the shaft, and it conducts a signal from the resistive element to the third leg of the potentiometer. The other two legs are attached to opposite ends of the resistive element.
The resistive element is the key to this part. It is usually a specific value. If the case or contact rings, shafts . etc.. are damaged, A similar potentiometer can be found and the parts traded.
Remove the insides, tacking careful note of how the parts are oriented. You will usually find a build up of silicone grease on the bottom side of the outer shell, and
on one side of the resistive element. Leave this alone as it is a lubricant for the rotating shaft.
Inspect the resistive element board.
Clean all of the dust off of everything and out of the case.
If it is dirty:
Use alcohol to clean the resistive element. Also clean any metal parts and contact rings. Basically anything that looks like it makes contact. You can tell where things rub by a shiny apperance.
Do not use harsh or abrasive cleaners as this may damage the resistive element or the contact ring.
IMPORTANT!!
When reassembling the potentiometer do not use a pliers to apply pressure to the top and bottom of the potentiometer this will distort the potentiometer case, and it will not turn correctly. Instead place on a flat surface and bend them down with the flat side off a pliers or screwdriver.
Never been a big fan of contact cleaner that contains lubricant in it. It will eventually gather all kinds of dust and dirt and create a bigger problem. A better solution is to carefully take the potentiometer apart and clean it.
There are usually little metal tabs which can be bent up
(with a needle nose pliers) and the faceplate can be removed.
Inside you will find a circuit board with a resistive coating on it. A potentiometer works by dragging metal contacts along the surface of the coating. There are hundreds of variations on how this is done , but most of the time a ring is secured to the shaft, and it conducts a signal from the resistive element to the third leg of the potentiometer. The other two legs are attached to opposite ends of the resistive element.
The resistive element is the key to this part. It is usually a specific value. If the case or contact rings, shafts . etc.. are damaged, A similar potentiometer can be found and the parts traded.
Remove the insides, tacking careful note of how the parts are oriented. You will usually find a build up of silicone grease on the bottom side of the outer shell, and
on one side of the resistive element. Leave this alone as it is a lubricant for the rotating shaft.
Inspect the resistive element board.
Clean all of the dust off of everything and out of the case.
If it is dirty:
Use alcohol to clean the resistive element. Also clean any metal parts and contact rings. Basically anything that looks like it makes contact. You can tell where things rub by a shiny apperance.
Do not use harsh or abrasive cleaners as this may damage the resistive element or the contact ring.
IMPORTANT!!
When reassembling the potentiometer do not use a pliers to apply pressure to the top and bottom of the potentiometer this will distort the potentiometer case, and it will not turn correctly. Instead place on a flat surface and bend them down with the flat side off a pliers or screwdriver.