Help to identify a potentiometer for replacement

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Help to identify a potentiometer for replacement

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#279958 18-Nov-2020 21:54

Hi all,

I’m trying to help my father in law repair his golf trundler, he seems to think there is an issue with the potentiometer in the speed control circuit, it also has an on/off position before the speed control kicks in.

There’s no part number or anything identifying on it.

I put a meter on the terminals and measured 10k ohms in what would be the fast position, open circuit when off.

There’s a number of pots available on trademe or rscomponents but I’m not sure what this would be called with the on/off switch, it has three terminals on the back of the pot as well as the standard 3 for the variable resistor near the front.

Photo attached if anyone can help ID how I can search a replacement part.

Thanks in advance for any help!

elpenguino

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#2606545 18-Nov-2020 22:41

Will be a bit tricky to find a switched pot as that's a bit unusual these days. Would have been more common with things like switched volume controls for radios 'back in the day'.

It's not clear from post your post. You say :

- I put a meter on the terminals and measured 10k ohms in what would be the fast position, open circuit when off -

Does this mean you measured on the green and blue terminals?

On those you should measure a variable resistance from , say 10 k, down to almost zero, not open, before the switch area, at least. It's possible the switch then does something to the value if you go into the switch's operating area.

Depending on the internal condition, it's not too hard to dismantle and clean a pot like this.

Un bend those tabs holding down the brown circle facing the photographer and away you go.

Other options are to mod the device for a separate switch with a generic pot.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

Technofreak

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#2606546 18-Nov-2020 22:47

Before you go too far.

Does the switch work OK and is there a good connection across the switch contacts (Close to zero ohms) when they're closed?

Measure the resistance between centre terminals and the one with the green wire. You may need to unsolder the green wire to get a valid reading. Do you get a nice smooth change in resistance? Probably easiest seen on an analogue meter.

If these all check out OK then I'd suggest your problem may be else where.

If your testing points towards a faulty switch/pot there are usually some identifying marks on the metal case which may be of use. I would go and look on a site like Element 14 or RS Components for an item like this. Jaycars may have it but the other places have a much wider range of parts.

Edit.

So far as giving it a clean goes, you will probably be just as or probably more successful squirting it with contact cleaner while twisting the knob.

Edit 2

One thing to consider with a replacement pot is to know whether or not it's a logarithmic or linear pot. I'd guess it's linear but you never know.

Edit 3

Something like this https://www.tubesandmore.com/products/potentiometer-alpha-audio-spst-switch

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Ortomator

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Geek

#2606864 19-Nov-2020 12:07

Hi elpenguino & Technofreak,

Thanks for the replies and the suggestions. I've taken the pot and desoldered the wires from the terminals and tested it out some more, its rock solid, smooth increase to 10K ohms and the switch looks fine, so as suggested maybe the problem is elsewhere, I've suggested clean all the connections to the speed controller. Maybe its some sort of overload or over temp cutout happening, I'm not sure, I havent seen the rest of the circuit.

Thanks again for the contributions

elpenguino

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#2606871 19-Nov-2020 12:26

no worries.

whats the bad behaviour the trundler is showing?

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

Ortomator

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#2606997 19-Nov-2020 15:03

elpenguino:

no worries.

whats the bad behaviour the trundler is showing?

From how it was described to me it had been used for a few hours and then began to stop when being used, it had to be turned off using the potentiometer switch and then back on again it would work again briefly before repeating

RunningMan

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#2607001 19-Nov-2020 15:11

More likely the battery is failing.

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SATTV

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#2607013 19-Nov-2020 15:56

RunningMan:

More likely the battery is failing.

I agree.

My father just updated his trundler battery to a Lithium one, same size, 1/4 the weight and same or better capacity, cost was a lot more but he is very happy.

I know enough to be dangerous