Im trying to find a replacement potentiometer, part i ordered was RV4NAYSJ103A. thought it was going to be right but i guess not.
original is a CLAROSTAT 368034.
the size is right, i’ll try to explain what i need. the way it is wired in, the two outter tabs are linked together, while the center wiper is by itself. I need it to read 5k ohm in the center (50%) position, then when rotated in either direction drop down to 0ohm. the 10k one i purchased not knowing anything about these things, when wired up sits at 2.5k ohm at home then drops in both directions.
hopefully someone can point me in the right direction, application is on an old YALE orderpicker, stand up forklift.
Hi ghiggins,
Welcome to the Tech Forum.
At first thought, I would have expected that the RV4NAYSJ103A would work exactly as you assumed it would. However, if you look at the actual circuit, you can see that 2.5k Ohms is correct for a 10k potentiometer.
If connected as drawn below:
This produces the following circuit when the wiper is in the center position:
Notice that in the circuit above, you actually have two 5k Ohm resistors in parallel, which equals 2.5k Ohms equivalent resistance.
Therefore, what you need to get a reading of 5k Ohms at the center position is a 20k Ohm potentiometer. It does not look like the RV4 comes in a 20k Ohm value, but it does come in 25k Ohm versions, which would be a max of about 6.25K Ohms when connected as you describe. If that’s not close enough, perhaps one of the other pots from this group might suffice.
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Thanks for the response, unfortunately i think it has to be 5k ohm so I may end up having to go through the dealer which is about 200$, was trying not to go that route.
That’s too bad.
Would none of these physically fit in your device? They would fit in the same hole cut-out size but body shapes vary and the shaft lengths are all significantly shorter.
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shaft length is the big one
One other possible option would be to use the RV4NAYSJ253A 25k pot and solder a pair of 50k Ohm resistors, one between each outside leg of the pot to the center wiper leg, as shown below.
With this configuration, at the wiper center point, it will be right at 5k Ohm equivalent resistance between the wiper and the outer contacts (labeled “A” and “B” in the diagram) tied together. As one turned the knob either way from the center point it would vary similarly to a stand-alone 20k pot, but would change at a somewhat different rate, so the “feel” might not be identical.
However, over a range of 70% left or right from the center point, the difference in resistance between a 20k pot and a 25k pot with the 50k Ohm parallel resistors is less than 11%, so it would be quite similar over that range.
Here is a table showing how the 20k pot compares to a 25k pot with the parallel resistors connected as described above:
| Equivalent Resistance AB to W (Ω) |
|
|
|
|
| Percentage Rotation from Midpoint |
20k Pot Alone |
25k Pot w/50k Ω Resistors in Parallel |
Absolute Difference |
Percentage Difference vs. 20k Pot |
| 0% |
5000 Ω |
5000 Ω |
0 Ω |
0.0% |
| 10% |
4950 Ω |
4960 Ω |
10 Ω |
0.2% |
| 20% |
4800 Ω |
4839 Ω |
39 Ω |
0.8% |
| 30% |
4550 Ω |
4633 Ω |
83 Ω |
1.8% |
| 40% |
4200 Ω |
4339 Ω |
139 Ω |
3.3% |
| 50% |
3750 Ω |
3947 Ω |
197 Ω |
5.3% |
| 60% |
3200 Ω |
3448 Ω |
248 Ω |
7.8% |
| 70% |
2550 Ω |
2827 Ω |
277 Ω |
10.9% |
| 80% |
1800 Ω |
2064 Ω |
264 Ω |
14.7% |
| 90% |
950 Ω |
1134 Ω |
184 Ω |
19.3% |
| 95% |
488 Ω |
595 Ω |
107 Ω |
22.0% |
| 100% |
0 Ω |
0 Ω |
0 Ω |
0.0% |
Looking through the standard resistor offerings, it looks like 51k Ohms is the common nearby value. The tolerance on resistance for the RV4 series pots is +/-10%, so one can use low-cost 5% tolerance 51k Ohm resistors such as the FMP200JR-52-51K and still be well within the overall tolerance of the original 20k pot.
