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Cleaning pots Little Mark II

Hawkbone

Hawkbone

Mar 23, 2009
942
251
Newfoundland
#1
Hi,

Input gain pot on my LMII is scratchy, but I can't see where to spray cleaner. The pots are sealed on the back and I'm reluctant to tug any harder on the knobs to remove them, without being sure that's how they come off.

Anyone know how to go about this?

Thanks

hawk
 
#4
Hawkbone said:
Hi,

Input gain pot on my LMII is scratchy, but I can't see where to spray cleaner. The pots are sealed on the back and I'm reluctant to tug any harder on the knobs to remove them, without being sure that's how they come off.

Anyone know how to go about this?

Thanks

hawk
Click to expand...
I bought a month ago a used LMT800, the Gain 1 was very scratchy and also the Master Volume. Since I know that they are sealed pots I removed the knobs and saw that there was a very small hole at the base of the shafts. So, this morning I sprayed DeoxIt D5 in these small holes and turn the shaft of the pots for about a minute or so and voilà no scratchy noise anymore. Hoping this will help those having this problem.
My first idea was to get the cleaner in the pots by spraying the shaft hoping the cleaner will get in the pots that way. I did that also so not sure if the cleaner got in that way only or both ways (Shaft + the small hole at the base of the shaft). The important thing is it worked.
 
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#7
GUY DES ROSIERS said:
Sorry I had such a hard time to pull out the knobs without damaging them they are back in place and I won't pull them out again to take a picture.
Click to expand...
I happen to have a picture and a few thousand of these pots... and I can guarantee that there is NO hole ANYWHERE on these parts. There are 2 tiny rivets on the diagonal corners, but they are solid. I have extensive experience with this part.

I bring this up because I do not think the "magic cure-all spray" had anything to do with your experience (as others have also suggested by simply rotating the control a few times).

It is impossible for the "magic cure-all spray" to reach the resistive element this way, period. For others reading this, IMO and IME, it's a false conclusion with the potential for causing additional damage to the amp.
 
#8
agedhorse said:
I happen to have a picture and a few thousand of these pots... and I can guarantee that there is NO hole ANYWHERE on these parts. There are 2 tiny rivets on the diagonal corners, but they are solid. I have extensive experience with this part.

I bring this up because I do not think the "magic cure-all spray" had anything to do with your experience (as others have also suggested by simply rotating the control a few times).

It is impossible for the "magic cure-all spray" to reach the resistive element this way, period. For others reading this, IMO and IME, it's a false conclusion with the potential for causing additional damage to the amp.
Click to expand...

What about the aspect of also spraying cleaner down the pot shaft Andy? I know where you stand and what I've been taught by some other very smart and experienced people, but I've also seen persisting contrary advice from various MI industry Interweb sources, even with just a bit of quick Google-Fu this morning. ;)
 
#9
agedhorse said:
I happen to have a picture and a few thousand of these pots... and I can guarantee that there is NO hole ANYWHERE on these parts. There are 2 tiny rivets on the diagonal corners, but they are solid. I have extensive experience with this part.

I bring this up because I do not think the "magic cure-all spray" had anything to do with your experience (as others have also suggested by simply rotating the control a few times).

It is impossible for the "magic cure-all spray" to reach the resistive element this way, period. For others reading this, IMO and IME, it's a false conclusion with the potential for causing additional damage to the amp.
Click to expand...
No doubt about what you are writing but the "magic cure-all spray" worked for me that's why I wanted to share it. I tried the rotating the control a few times (it did'nt work) that's why I decided to give a try to spray directly the shaft and the famous small hole (maybe its'not an hole it may be a grip for the pots to stay in place. If you have an LMT800 on hand remove the gain 1 knob and you will see the famous small hole that I saw at the bottom part of the shaft. My LMT800 is dated 09-2016 maybe the buid changed trhrough the years. The important thing for is that worked for me. What can be said more?
 
#10
Passinwind said:
What about the aspect of also spraying cleaner down the pot shaft Andy? I know where you stand and what I've been taught by some other very smart and experienced people, but I've also seen persisting contrary advice from various MI industry Interweb sources, even with just a bit of quick Google-Fu this morning. ;)
Click to expand...
It's just about the worst thing you can do to a pot, and on this type of pot it's virtually impossible to do this effectively due to the smaller diameter bushing being overlapped by the return on the pot shaft. These pots are assembled in the reverse order of the typical 16mm pots. Regardless, it's a quick way to ruin a pot IME, and when the "magic cure-all spray" gets on other components it can cause additional damage.
 
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#11
GUY DES ROSIERS said:
No doubt about what you are writing but the "magic cure-all spray" worked for me that's why I wanted to share it. I tried the rotating the control a few times (it did'nt work) that's why I decided to give a try to spray directly the shaft and the famous small hole (maybe its'not an hole it may be a grip for the pots to stay in place. If you have an LMT800 on hand remove the gain 1 knob and you will see the famous small hole that I saw at the bottom part of the shaft. My LMT800 is dated 09-2016 maybe the buid changed trhrough the years. The important thing for is that worked for me. What can be said more?
Click to expand...
There is an anti-rotation pin on the pots that some manufacturers break off, if this results in a "famous hole" then the pot was ruined before it was installed (and it's VERY hard to break it in a way that creates a hole).

My point is that this is bad advice in general, though it may have APPEARED to work for you. For others, it may create bigger and more serious damage, hence the warning... I see gear that's damaged by exactly what you did all too often. I get it that you are giddy with "success", my experience suggests that it's coincidence.
 
#12
agedhorse said:
There is an anti-rotation pin on the pots that some manufacturers break off, if this results in a "famous hole" then the pot was ruined before it was installed (and it's VERY hard to break it in a way that creates a hole).

My point is that this is bad advice in general, though it may have APPEARED to work for you. For others, it may create bigger and more serious damage, hence the warning... I see gear that's damaged by exactly what you did all too often. I get it that you are giddy with "success", my experience suggests that it's coincidence.
Click to expand...
With what I read from you be sure that I'll "never again" post anything on Talkbass.
 
#13
GUY DES ROSIERS said:
With what I read from you be sure that I'll "never again" post anything on Talkbass.
Click to expand...
Don't be silly, petty or juvenile. Just post things that are truthful and do not pose the risk of damage to the equipment others who may read what you post. My objection is that what you posted is not correct or accurate, and could cause additional damage from somebody who follows your advice.
 
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#14
For the record, as the OP, I haven't tried to clean the pots and the amp works just fine so I'm not inclined to mess with it.
Thanks for the post, Guy, but please just take agedhorse's advice for what it is - good advice from a well respected member with piles of experience.

hawk
 
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#15
As it happens I had a knob pulled off my LMII last night just for this reason: scratchy pots. The “hole” that seems to be there is just a notch in the sheet metal face plate, at the 6:00 position. It is not a hole in the pot itself.
 
#16
Hawkbone said:
For the record, as the OP, I haven't tried to clean the pots and the amp works just fine so I'm not inclined to mess with it.
Thanks for the post, Guy, but please just take agedhorse's advice for what it is - good advice from a well respected member with piles of experience.

hawk
Click to expand...
Piles of experience does not allow "a pseudo expert" to destroy my experience. With that number of members having this problem for many years I was so happy to share what occur with me cleaning my posts on my LMT800. Be sure it works what ever this expert that has been suspended in 2019 said about me. How can I be so stupid to take members to try something that may cause them to have problem. What would be my goal to do that???
 
#18
Hawkbone said:
Hi,

Input gain pot on my LMII is scratchy, but I can't see where to spray cleaner. The pots are sealed on the back and I'm reluctant to tug any harder on the knobs to remove them, without being sure that's how they come off.

Anyone know how to go about this?

Thanks

hawk
Click to expand...

Is the pot/part still available new? If so, I would just have the pot replaced by a service tech. New part, no more issues.
 
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#19
From back when I signed up here, people have been recommending Deoxit for "scratchy" pots, and I'm glad I took that advice. None of my gear is expensive stuff - so if the cleaner doesn't work - then it's time for some new gear. Also, there aren't any techs (that I know of) that I can send gear to for repairs, and if I did - it would probably cost less to just replace it.

It's worked fabulous for me on several used basses, and a couple pedals.
 
#20
boing said:
As it happens I had a knob pulled off my LMII last night just for this reason: scratchy pots. The “hole” that seems to be there is just a notch in the sheet metal face plate, at the 6:00 position. It is not a hole in the pot itself.
Click to expand...
The notch in the sheet metal is a clearance hole for the anti-rotation tab on the pot. You are correct that it is not a hole in the pot itself.

The factory pots are available, they are not expensive, and is the proper way to repair the amp properly. Otherwise, IMO, you are better off leaving things alone than attempt the Mickey Mouse repair that was suggested. Right now, you have a working amp. I see the results of Mickey Mouse repairs (often suggested by those who simply don’t understand, even if they mean well) and many times it results in a simple, inexpensive repair becoming more expensive.
 
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