[SOLVED] Identifying this potentiometer

[seamrog]

Hi Folks,
I'm a newbie here, long time lurker first time poster.. and am repairing an intercom with a probable faulty potentiometer that is used to adjust the speaker volume.

The potentiometer I'm replacing is a Piher horizontally mounted one with the number 5K529M written on the side of it. This leads me to think that it is a 5K ohm potentiometer. Does anybody know what the 529M part is about? I've googled the number of course but no joy. I'm concerned that because these potentiometers come with different numbers on them that they may be different specs.

 

[tpetar]

Piher Trimmers.


http://www.piher-nacesa.com/pdf/14-PT15v03.pdf

 

[FvM]

I presume, the potemtiometers are operated by put-on knobs not shown in the photo? In this case, you should check (by intelligent use of a multimeter) if the potentiomters have possibly a log characteristic. But standard linear PT-15 would be my first guess.

What makes you think the potentiomters are defective?

 

[seamrog]

Piher Trimmers.


http://www.piher-nacesa.com/pdf/14-PT15v03.pdf

Cheers for that tpestar, sure are a lot of variations! Now I'll try and figure out how those numbers I have relate to the part number for ordering.

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I presume, the potemtiometers are operated by put-on knobs not shown in the photo? In this case, you should check (by intelligent use of a multimeter) if the potentiomters have possibly a log characteristic. But standard linear PT-15 would be my first guess.

What makes you think the potentiomters are defective?

Yes there are put on knobs. I think it may be defective as when the knob is turned the speaker often crackles. I figured it would be a good place to start looking at the pot.

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There's also a "Y" on the pot between the 2 pins on the top side, just about visible in pic. On the pot for the microphone there is a "N".

 

[seamrog]

I've found that the 5K8 means 5800 ohms, kind of hard to source that spec though. Anyone know what the rest of 5K829M could be?

 

[FvM]

Yes there are put on knobs. I think it may be defective as when the knob is turned the speaker often crackles. I figured it would be a good place to start looking at the pot.

Might be if the device is old or the potentiometer has reached end of life in terms of operation cycles. Unwanted DC across the potentiometer due to a defective capacitor or other component fault can have the same effect, however.

I've found that the 5K8 means 5800 ohms

I'd bet against it. 5k is a Piher catalog value, 5k8 not even a resistor standard value and within 20% tolerance of the 5k standard value, the difference won't matter in a usual potentiomter circuit. You're definitely on a wrong track.

I already suggested how to proceed, nothing to add presently.

 

[betwixt]

It's 5K and I think the rest of the digits are a manufacturing date code, it seems to tie in with the other component dates around it.

Just about any potentiometer will work as an electrical replacement but you will have to be careful about the shape of the center hole if a shaft fits through it.

Brian.

 

[BradtheRad]

The circular resistive surface inside could be dirty. Especially if it has been in a smoky or greasy atmosphere.

See if you can take apart the scratchy potentiometer to get at the innards.

Clean them with a cloth moistened with electrical contact cleaner (or solvent that leaves no residue).

The contact area on the brass wiper arm can accumulate dirt or grease.
To clean it, slide a bit of paper under it. Moisten the paper with solvent. Move the parts around.
Careful, you don't want to break anything.

 

[betwixt]

I don't think you can open this type of potentiometer. The black body is placed over the back plate then welded around the edges. They are difficult to dismantle without damaging the plastic body and if they don't go back together fully, the wiper and ring spring tensions inside may be wrong. They were manufactured down to a cost rather than up to a specification.

Brian.

 

[BradtheRad]

Yes, it may not be able to be disassembled.

----------------------------------------------------

Here is another possibility:

A hairline ***** in a solder connection. Excess flexing on the knob might do this.

 

[betwixt]

It's good job there isn't an illegal substance called 'fracture' isn't it!

Brian.

 

[FvM]

As far as see from the photo, the potentiometer is PT15NV02 type variant. It's basically available from Mouser, but unfortunately they don't stock the removable shaft "N" variant. https://de.mouser.com/ProductDetail...=sGAEpiMZZMtC25l1F4XBU6ha6eQlhgy7840csJV2lT0=



The closed design doesn't pick up dirt, but unless it's the optional long-life type, it's designed for 500 cycles only.

 

[seamrog]

I've gone for these parts:

Potentiometer: https://www.tme.eu/en/details/pt15nv-5k/single-turn-tht-trimmers/piher/pt15nv-5k-a2020/#
Trimmer knob https://www.tme.eu/en/details/pt15gw-12b/trimmers-knobs/piher/
Adjustment knob https://www.tme.eu/en/details/17_6alu/shaft-resistors-knobs/mentor/506611/#

The knobs aren't exactly what I want but look close enough I guess.

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I've gone for tme.eu for the purchaae. I could maybe have chosen any place really. Who do you guys find good i.e. well stocked, priced. delivery charges etc. ?

 

[tpetar]

829M is manufacturing date.

I just received that info from Piher.


Best regards,
Peter

 

[seamrog]

829M is manufacturing date.

I just received that info from Piher.


Best regards,
Peter

Thanks for the info there Peter.

I ordered the pot about 0.5 euro. Works a treat Some super tech info posted here, thanks for the help folks!