Need help finding POTS for MARSHALL MAJOR BASS amp: 28mm (1.1") body diameter

[kka]

Would anyone please help me locate replacement pots (all of them) for this vintage amp? They are the bigger body size, most likely 2W versions with 28mm bodies (1.1"). I looked all over the Internet and could locate here and there a few pots that fit, but all from different manufacturers and look different. I need a uniform look. I would hate to replace them with the 24mm 1/4W standard pots....

250k L
25k L
1M A
470k A (or 500k)
5k L (or 4.7k)


Thanks !

[Tom Phillips]

May I ask why all of the Pots in the Major need to be replaced?
Maybe they can be restored and maybe we should discuss that first.
Just seems unlikely that they all went bad unless the who amp has had some ext ream abuse.

[kka]

May I ask why all of the Pots in the Major need to be replaced?
Maybe they can be restored and maybe we should discuss that first.
Just seems unlikely that they all went bad unless the who amp has had some ext ream abuse.

This amp was in storage for over 20 years. All pots are stuck and don't move at all. I tried cleaning them without success

[Leo_Gnardo]

This amp was in storage for over 20 years. All pots are stuck and don't move at all. I tried cleaning them without success

With the knobs off & out of the way, try getting some penetrating oil like WD-40 into the gap between shaft and bushing. Just needs a drop in the right place - you don't have to hose 'em down. Point the shafts up & let the oil sit in that gap overnight. Grab the shaft with a big pliers tomorrow & see if you can work 'em loose.

If that doesn't do it, don't worry about the body diameter or power rating for replacements. The power dissipated by pots in a guitar amp is a small fraction of a watt. Pots made currently by Alpha and/or CTS will work just fine, you can get em from Antique, Mojo, Weber and lots of other places.

[mac dillard]

What Leo said, but use Kroil oil. That stuff is magic when it comes to penetrating oil.

[kka]

With the knobs off & out of the way, try getting some penetrating oil like WD-40 into the gap between shaft and bushing. Just needs a drop in the right place - you don't have to hose 'em down. Point the shafts up & let the oil sit in that gap overnight. Grab the shaft with a big pliers tomorrow & see if you can work 'em loose.

If that doesn't do it, don't worry about the body diameter or power rating for replacements. The power dissipated by pots in a guitar amp is a small fraction of a watt. Pots made currently by Alpha and/or CTS will work just fine, you can get em from Antique, Mojo, Weber and lots of other places.

Thanks for the tips. I have tried everything already. I am also aware of the facts you mentioned about the replacement pots. I am getting this amp ready for a customer and he wants it to look as original as possible with the big 28mm pot diameter as this is a vintage amp and a collector's item. So, I'm doing my best to accomodate him. Worst case, I will replace the pots with the standard 1/4W 24mm versions.

[Leo_Gnardo]

he wants it to look as original as possible with the big 28mm pot diameter as this is a vintage amp and a collector's item. So, I'm doing my best to accomodate him.

Maybe PEC pots then. Haven't seen any up close lately but IIRC the ones I find in old Traynors are a little bigger than average diameter. About $10 each.

[J M Fahey]

If he´s such a collector/vintage fan and looks are more important than actual functioning, then just clean the amp and leave it as is.

I wonder if his bandmates will open the amp and point a finger at him because pots are 24mm instead of 28mm .

[Leo_Gnardo]

Another angle of attack in case you haven't yet tried it: pry off the pot cover & get some penetrating oil into that shaft/bushing area from the inside. Ordinarily I wouldn't suggest this but it's do or die.

Juan, some of those collectors can be merciless. We have a couple of impolite terms for them but I'll spare you , could get me in trouble with our moderators.

[kka]

If he´s such a collector/vintage fan and looks are more important than actual functioning, then just clean the amp and leave it as is.

I wonder if his bandmates will open the amp and point a finger at him because pots are 24mm instead of 28mm .

The owner stopped playing and took it out of storage to sell. I had already warned him that it might be hard to get the same kind of pots...

[kka]

Maybe PEC pots then. Haven't seen any up close lately but IIRC the ones I find in old Traynors are a little bigger than average diameter. About $10 each.

Thanks, I had found some PEC pots I could use, but not all of them. That is the problem. I need all pots to be the same.

[kka]

Another angle of attack in case you haven't yet tried it: pry off the pot cover & get some penetrating oil into that shaft/bushing area from the inside. Ordinarily I wouldn't suggest this but it's do or die.

I will try that with 1 of the pots to see if it is possible. Thank you.

[olddawg]

I will try that with 1 of the pots to see if it is possible. Thank you.

If it is a restoration, take a picture before you start. Then remove all the pots completely. Buy a CAN not a spray can of Caig Deoxit. Soak them for a few days. (You might try just one first ) if you have a sonicator it will help. (You can make one with a speaker, amp, and plastic tub. Once they turn, take them apart, retention the whipers, and reassemble with the proper lubricants. There are very few pots that cannot be restored unless the element has cracked or the wiper is worn through. Just take your time and never force anything.

[Enzo]

Put something to protect the panel, but maybe some heat to the shaft will loosed the old hard dried out lube.

[J M Fahey]

Maybe this will be shunned upon in technologically advanced USA but in our little shops in gaucho "rancho" homes in the middle of the Pampas we pull the old kerosene lamp from its nail in the mud wall, pour said kerosene inside a glass or cup and drop offending pots or switches inside for some time, 2 days if necessary.
It sure softens and cleans old gunk.
And it does not attack plastic.
Now I should find what "plastic" means

Here´s a couple customers outside the shop testing their guitars:



They are also consuming an evil green vegetable substance made out of chopped plants with psychotropic properties: