1. Determining the Potentiometer Legs
Potentiometers have 3 main legs, and usually there are 2 additional legs. To make it easier to distinguish the legs, they are marked with the numbers 1, 2, 3 or a, b, c on the symbol.
Potentiometer Architecture
How to determine feet number 1, 2 and 3 is as follows:
- Hold or position the potentiometer in such a way that the legs of the potentiometer are at the top and the axle is 'further' from your eyes.
- Note that the leftmost leg is leg a (1), the middle leg is leg b (2) and the rightmost leg is leg c (3).
- Match it with the symbol. Generally, leg a is ground, while legs b and c just need to be adjusted.
2. Measuring and checking the potentiometer
- When measuring leg a with leg c, the needle moves to show the ohm value as written on the potentiometer body, meaning the potentiometer has the correct ohm value.
- When measuring leg a with leg b while the potentiometer axle is rotated, the needle moves according to the rotation of the axle without stuttering, meaning the potentiometer is good.
- In measurements such as point b, the needle moves jerkily, meaning the potentiometer's carbon layer is dirty.
- If we take measurements and the needle moves fully (does not show the ohm value as written on the potentiometer body), it means the potentiometer is short.
- If the needle doesn't move, it means the potentiometer is broken/damaged.
3. Damage that often occurs to resistors
- The ohm value of the resistor changes
- The charcoal layer on the potentiometer or potentiometer trimer is worn/dirty. The way to overcome this is by spraying 'Contact Cleaner' or by moving the potentiometer contact path.