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ADA Power Amps => Microtube 200 MT-200 => Topic started by: calan on April 10, 2016, 01:57:32 AM

Title: Replacement pots for MT200
Post by: calan on April 10, 2016, 01:57:32 AM
Can someone point me to some replacement pots for the MT200?

Values, part numbers, and a source (preferably Digikey) would be great.   ;)

*****

I may have another issue, but I think I fried the B channel pot while cleaning it. It was a bit scratchy, but working. As I was turning it back and forth to clean it up, it suddenly got very easy to turn, and the amp is now stuck in mono mode. Even when using both input and output jacks, both channels are controlled by channel A's volume pot. Otherwise, the amp still sounds fine.

Title: Re: Replacement pots for MT200
Post by: MarshallJMP on April 10, 2016, 10:14:21 AM
These are A50k pots,so 50k log.Can you post a pic so i can see what model it is?

Now the problem you have doesn't look like a pot problem.Did you clean the jacks too?
Title: Re: Replacement pots for MT200
Post by: calan on April 10, 2016, 01:49:58 PM
A external pic of the amp, or the internals? (It's still in the rack for the moment, but I'll yank it soon).

I didn't clean the jacks. It was hooked up in stereo and working, but with a scratchy B pot. Powered it off, cleaned the pot, felt the pot go really light, and when I turned it back on it was in mono mode. Removing and reinserting the rear plugs a few times doesn't change anything.
Title: Re: Replacement pots for MT200
Post by: MarshallJMP on April 10, 2016, 03:38:28 PM
A pic of the pots.

Again i find it strange.Seems more of a jack problem since these do the switching.
Title: Re: Replacement pots for MT200
Post by: rnolan on April 10, 2016, 10:09:26 PM
Probably a good idea to change the jacks as well while you have it open, and from what MJMP says, as they do the switching (mono to stereo mode), that could well be why it's now stuck in mono.
Title: Re: Replacement pots for MT200
Post by: calan on March 16, 2019, 05:06:25 PM
Only 3 years later, but here are the pics of the pots (put the thing in the closet and forgot about it  :D)

The original problem "fixed itself". Just have a scratchy channel B pot that needs to be replaced.
Title: Re: Replacement pots for MT200
Post by: MarshallJMP on March 19, 2019, 09:32:51 AM
Better late than never hahaha  :thumb-up:

These are 16mm alpha pots pcb mount A50k.
Title: Re: Replacement pots for MT200
Post by: calan on March 23, 2019, 07:06:28 PM
Thanks much. Do you happen to have a source or manufacturer part number?

I can probably browse around on Digikey and find something similar if not.
Title: Re: Replacement pots for MT200
Post by: MarshallJMP on March 26, 2019, 05:40:13 AM
Where are you from?
Title: Re: Replacement pots for MT200
Post by: calan on March 26, 2019, 07:14:50 AM
central Oklahoma
Title: Re: Replacement pots for MT200
Post by: MarshallJMP on March 26, 2019, 10:02:36 AM
https://www.jameco.com/z/RV16AF-20-15K-A50K-Taiwan-Alpha-Electronic-50K-Ohm-60-mW-16-mm-20-0-235-Inch-Knurl-Shaft-PCB-Mount-Audio-Taper-Potentiometer_2269215.html
Title: Re: Replacement pots for MT200
Post by: calan on March 26, 2019, 04:33:23 PM
Awesome!

So that is a direct replacement?

I'll order 6 or 8 at that price.  :)

EDIT:

Couple more questions if you don't mind...

1). Is the presence pot the same?

2). Anything else I should pick up and replace while I'm digging around in it? (I replaced the neon lamp and a couple of resistors a few years ago).

3). Is there a relatively easy way to get a bit more power out of it? I'm flashing the yellow LED's while driving a couple of 8 ohm 1x12 cabs, and it's no where near as loud as my 15 watt 5150 LBX II driving them directly at half volume, with the attenuator on (although to be fair, the LBX II is a tube amp, and is INSANE for 15 watts. :D )
Title: Re: Replacement pots for MT200
Post by: MarshallJMP on March 27, 2019, 03:37:09 AM
That should be a direct replacement from what I can see.

The presence pot is a stereo C10k pot, also 16mm but C types (reversed log) are harder to find.
I found these but it's in the UK
https://www.hificollective.co.uk/catalog/alpha-potentiometer-stereo-c10k.html
Title: Re: Replacement pots for MT200
Post by: calan on March 27, 2019, 09:25:26 AM
Thanks much for all your help!
Title: Re: Replacement pots for MT200
Post by: MarshallJMP on March 27, 2019, 01:37:16 PM
No problem, looked in my own stock but I only have the single version of a C10k
Title: Re: Replacement pots for MT200
Post by: calan on March 31, 2019, 10:25:32 PM
Channel pots arrived in just two days from Jameco, replaced them and it works great.

Thanks again for all your help.  ;)

Title: Re: Replacement pots for MT200
Post by: rnolan on March 31, 2019, 11:45:23 PM
 :whoohoo!: :thumb-up: