Markbass LMIII tiny, tiny, tiny scratchy pots.

The pots are basically sealed - it’s unlikely IMHO that they are contaminated by dust. Scratchy pots are also caused by DC leaking into their circuits. You should take the amp into a MB service place and get it diagnosed properly. Many, many pots have been ruined by the application of so called contact cleaner.

 

Don't do it. You'll trash the pots. They'll still work, but they'll be super loose and able to be moved even by vibration.

 

Do what I did. I sat in my living room and turned the knobs back and forth for about an hour. Scratchiness went away. I bought a LMIII a couple months ago. The volume knob was scratchy. I just turned the knob back and forth for about an hour.

 

+1000 this has worked for me many times.

PSA when cleaning pots always use Lubricated Contact Cleaner.

 

Turn them til they quit scratching, 10 minutes tops.

 

Well maybe not an hour but I was watching TV and I just turned the knobs while watching. I didn't have any cleaner/lube and according to a post above, the pots are sealed or not easily accessible anyway. Doesn't matter. My knobs are noise free.

 

I bought a month ago a used LMT800, the Gain 1 was very scratchy and also the Master Vollume. 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.

 

Yesterday I forgot to mentioned that 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 theb ase of the shaft). The important thing is it worked.

 

What ever said agedhorse my positive experience with DeoxIt D5 with my LMT800 is now and for two weeks today positive my pots are scracth free and works just fine.