Does leaving the volume pot at ~3 o'clock for years damage it?

[Doodski]

I leave my Schiit Heresy headphone amp behind the monitor to collect dust. I plan on doing this for years. I repaired a large Kenwood integrated with a huge volume potentiometer assembly. The pot had a very tinyyy tiny spot on the dial @ about 1:30 that would cause a snap/crackle and I wondered what would cause this? Is it possible leaving a pot in one position for years can cause wear at the microscopic electronic level?

 

[Zek]

There can be several causes - dust has accumulated over time or the potentiometer has oxidized. Look for some cleaning spray, it might help.

 

[restorer-john]

Any offset from poor upstream components or leaky caps/DC on the wiper will cause that.

I have few pieces of test gear that develop issues like that. My old signal generator set at 1kHz (exactly) needs a new dual gang matched pot every 15 years due to the same issue.

 

[Doodski]

There can be several causes - dust has accumulated over time or the potentiometer has oxidized. Look for some cleaning spray, it might help.

The pot was treated with a strong cleaner lubricant and it still had that very small position where it could pop tweeters.

 

[DVDdoug]

As you probably know, sometimes multiple full-sweeps will "clean-up" a pot, at least temporarily. But years of active operation could do the opposite and wear it out so I'm not sure which is worse...

Is there a difference between 3PM and 3AM?

 

[Doodski]

As you probably know, sometimes multiple full-sweeps will "clean-up" a pot, at least temporarily. But years of active operation could do the opposite and wear it out so I'm not sure which is worse...

Is there a difference between 3PM and 3AM?

Yes, I've attempted wearing through the dirt to a better contact and lots of solvent cleaner/lube and keep going at it but it was pointless. That volume control assembly to replace with a like or better assembly would cost in the multiple hundreds for one if one could even be found. So into the suspect amp category that it might pop tweeters if used around that volume position. Yes, I see it now...LoL.

 

[sam_adams]

DC on a pot is a death sentence over time. Even the legendary Allen-Bradley Type J pots never survived for long.

 

[MaxwellsEq]

If you know it will be in the same position for years, you could swap the pot for a resistor divider network and add the pot back in if you want variable control again.

As others have said, DC will cause a problem. I also imagine that, even without DC, if the period is long enough there may be chemical interaction between the wiper and track leading to something similar to a tiny cold weld.

Mixing desks have hundreds of pots, some of which don't get moved often. They can be crackly as a result and benefit from the occasional sweep or clean.

 

[Chrispy]

Curious, can't you find something more suitable that doesn't have such a pot (or need one)?

 

[Doodski]

Curious, can't you find something more suitable that doesn't have such a pot (or need one)?

I don't want to spend the moola for higher end volume control methods. I'm curious what info would pop up if I posted this thread and I have some info now. Use it and if it develops an arc spot on the pot resistor element then buy a new one.

 

[Chrispy]

I don't want to spend the moola for higher end volume control methods. I'm curious what info would pop up if I posted this thread and I have some info now. Use it and if it develops an arc spot on the pot resistor element then buy a new one.

Just hard for me to imagine a use for this in the first place, so curious.

 

[Doodski]

Just hard for me to imagine a use for this in the first place, so curious.

For a technician or EE it is very good knowledge to understand what causes this major issue in some gear. I never knew about it's cause but I've been aware of the effect for decades and I was never able to 100% determine a cause that could be repaired. I knew something was damaging the pots at a miniscule location at the resistive element but I never had a conclusive hint at the root cause.