Marshall amp pot replacement

[smac4th]

So today while I was using my valvesate vs100 the volume pot on the overdrive 2 channel went bad on me. The pot was getting crackely not only by feel but also through the speakers. when I used it and today it came to the point where the pot had to held a certaint way so I still had some use of the volume and to where it would not automaticly go to full volume on its own. The same thing happened with the volume pot on the overdrive 1 channel except the pot didn't get crackely it just wore out. I still have use of all of the pots used for EQ, reverb, FX, and clean channel volume. Since the amp was given to me by a friend for free I don't mind having to fix the amp. Anyway the amp is 16 years old. Is it not uncommon for the volume pots to go bad considering they are the origanals. I ordered the pots from amprepairparts and they should show up Friday or Saturday.

[Chuck H]

Are you just reporting or did you have a question about something? It sounds like you're on track with the diagnosis.

[smac4th]

Are you just reporting or did you have a question about something? It sounds like you're on track with the diagnosis.

Sort of both, I am reporting what I have found and what I am doing to fix it. I'm also asking for is it more common than not for an apm of this age (16 years old) to have the volume pots go bad already?

[The Dude]

If you look at the "quality built pots" Marshall uses when you replace them, it will answer your question.

[Jazz P Bass]

It sounds to me (had to hold the pot in one spot) like the pot 'took a hit'.
That is not how they typically fail.

[smac4th]

When I got the amp they must have alreadybeen damaged because they were fine until today becaause Iput the amp to really good use and I was adjusting the volume quite a bit and that was what caused them to finnaly fail. The volume on buth overdrive channels were starting to get mor crackely as well so either way they were going bad. All other pots though are quiet when in use and operate normal.

[The Dude]

Sometimes on those Marshalls, the wafer gets jarred back of the mechanism. If you look at the back you'll see little tabs that hold the wafer in place. Makes sure those aren't bent back. Many times you can correct the problem by just pressing the tabs back in tight........... They're still crappy pots, though.

[Chuck H]

It may be telling that it's only the volume pots. They would seem to get the most use. Dude alluded to the truth of it. I had a 900 for a time and I had to replace two pots after only one year of gigging with it. My old JMP had no such trouble, but the pots did have plastic shafts. I don't suppose Marshall EVER spent more than they had to on pots

[Enzo]

If holding it a certain way makes it work, then I'd have to agree with the thought it is sprung. Pots are held together by little metal tabs bent over, if those tabs start to bend back up, the thing is not held tight together, and the contact inside can stop working.

[smac4th]

When I took the amp its self out of the wood and tolex housing to make it look pretty I actually made sure to check the backs of each pot. They were clamped down as they should be. The pot on OD2 was crackely not only by sound when turned on but alsso by feel. The volume pot on OD1 was starting to get all crakely but went bad before it was as bad as the pot on OD2.

[smac4th]

It may be telling that it's only the volume pots. They would seem to get the most use. Dude alluded to the truth of it. I had a 900 for a time and I had to replace two pots after only one year of gigging with it. My old JMP had no such trouble, but the pots did have plastic shafts. I don't suppose Marshall EVER spent more than they had to on pots

Wouldn't supprise me, I have had many of the square shaped pots go bad on me with normal use but they were used for different applications.