How to repair a tube amp with Scratchy Pots?

oldskoolstreet

New member
Tube Amp with Scratchy pots is a One Trick Pony. Solid-states are quite easy to fix because they do not get very warm or hot like a tube amp. So the tendency for a wear and tear of the Pots are less. Tube Amps get extremely hot, and their circuit boards are just about the same temp as a cooked egg in a pan. Overtime, these Pots have a tendency to wear because High-End Audio Pots are very sensitive. Especially when heat penetrates into its rheostat range and slowly melts away its durability. To make it worse, you don't play that amp very often.

Now here's where Oxidization sets in, corroding, eventually interfering with the smooth operational function.

Just over this weekend, I helped a close friend, who is a hobby rocker, to fix his Marshall JCM 900 and a Mesa Blues Amp that was experiencing scratchy pots. Well let me tell you that it took the whole of my weekend, and I never had the chance to spend the first weekend just after school holidays with my kids and family.

Scratchy pots are a nightmare and if your amp can swell up to its mark, say a max of 100w, then it is a big trouble.

You will need to turn on your amp from standby and wait up to 2 hours for heat to radiate throughout. Remove the thumb-friendly knobs from the Potentiometers affected. Inject a Spray called "Jackie Spray 60" over the affected pot. Your fingers willl have to do the dirty job now. Turn clockwise and anti-clockwise in very swift movements with your greasy fingers. You need to do this when your amp is ON. If the effect from the Amp is extremely loud, you will need to invest in an Attenuator to help you achieve this so that your Neighbour doesn't call the Police for Noise Pollution :)

You have to burn the night and day twisting and turning the scratchy pot with volume to hear every bit of sound that goes. It may snap, crackle or pop loudly... but keep doing that thing (turn left-right-left-right-left......) until the scratchy effect diminishes slowly.

And voila ! You will finally have that "Scratchy Pot" issue resolved at the cost of the Spray. :) Hope this helps. Patience is the word.

I have resolved amplifiers after a week of twisting and turning, smashing my dreams....
 
Some comments & Updates
Okay guys you don't need that so call particular spray "Jackie Spray 60" only to work. Just go to any hardware shops and ask for Contact Cleaners.
And you don't need to turn On the amp to repair that scratchy pot, all you need to do is find an access hole on the pots and spray the contact cleaner in. Like what Oldskoolstreet suggest, turn it clockwise and anti clockwise several times maybe for about 2 to 3 mins. You can use this technic on any pots like guitar pots, your hifi, radios ...etc as long as it's call pots(potentiometers) meaning adjustable variable resistor. It can be in linear form too meaning a Slider like in your PA system or recording equipments.
 
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