Replacement Output Jacks for MT-200

[Dante]

I have a small crackle in Channel B of my MicroTube 200 that comes & goes....so, I took the cover off the amp and was about to unscrew all the jacks to reflow the solder on that little PCB that they're all mounted to (I/O Jack board)....when i see that several of my 'plastic barrel' jacks are cracked, one is broken. I need to replace those plastic ones. The two metal ones are fine of course.

I found this thread about someone else describing a similar crackle, here's what they did:

My MT200 is alive again.  Not sure which task actually repaired the problem, but I went through all the suggestions posted in this thread.


1.  Replaced the CD4053 IC.  Picked up 5 locally for .35 cents a piece. 
2.  Removed the I/O jack board, and sprayed all the jacks down with Caig Deoxit 100% Cleaner
3.  Used a can of compressed air, clean out the inside, with particular focus on the fan area.
4.  Reflowed the solder on every visible joint that I could reach, with dissasembling.
5.  Put the original Svetlana 12AX7s back in the amp.

Anybody know what jack replaces those? Pics below for posterity

[Harley Hexxe]

Dante,

   I think those might be one of the proprietary parts used by ADA only and may not even be in production anymore. The only one I can think of who might possibly know would be MJMP. Or at the very least, what type of jack might be a suitable replacement.

[Dante]

I'm going to yank one out, see if I can spot a part number or a suitable replacement. Worst case scenario, I'll wire some regular jacks and run wires to the little board, just have it tucked inside somewhere.

I found this (below), but again, I don't have one out to compare (yet). It's a mono plug from MojoTone, they also have a stereo version

[Dante]

UPDATE:
Okay, I pulled one out (desoldered it) - the one with the broken plastic barrel. Turns out, I only have one that's broken, the others have a split in them & it appears they're supposed to have that.

These are not normal jacks, there is a contact inside that gets pulled apart when you insert a cable (see pic below). I guess that's the 'switch' part of the jacks. I was unable to find anything like that online.

However, I did reflow all the solder points on that little I/O board and it seems to have resolved my crackling issue! Yay! I very carefully put that broken plastic piece back in place and gently screwed the nut back on....don't bump in to it! haha

It tested good, then I let it sit for a few minutes and tried it again....NOISE. dammit...I'm not done

[Dante]

Aaannnndddd.....I've turned on the beast and rocked out accordingly several times now. Haven't heard the noise since that first one

That first time; it made it's customary crackly pop sound but this time it had a fffffffFFFFF behind it. Went away after a few seconds....hasn't come back. I hate that

It's only been a day - lemme run it through the ringer for a few days and see if it's actually okay

[Harley Hexxe]

Dante,

That sound you described after the pop, makes me think of a capacitor, like it's not getting full voltage. Maybe look for any dull or cracked solder joints in the circuit path that might need a refresh? Caps make funny hissing noises like that when voltage fluctuates.

[Dante]

It's been over a week, not a peep of noise outta that MT-200 (crossing fingers) since the first time. Been using it exclusively to test it out. I'd say it's fixed, except for that first noisy experience that has me suspicious.

I did a quick visual inspection, didn't disassemble anything while I was in there reflowing the the I/O board. Nothing looked 'cooked' or discolored. All the caps look fresh, it was recapped when i bought it and I haven't used it all that much since then...it's been a backup rig.

I plan on getting a can of air today and blowing that thing out...poking around in there. I really wanna blow out that fan & the surrounding areas...it's been years since that was done

[Harley Hexxe]

Fingers crossed.

[rnolan]

Blow by Blow

[Harley Hexxe]

Blow by Blow

Good Album 

[MarshallJMP]

So I see it's the bridged output that is busted? That's a very special jack and I was never able to find one.
I have all the input and output jacks but not this one. It's actually a mono jack but it has an isolated contact that tells the MT200 switching circuit that a jack is plugged into the bridged out so it will phase shift one output 180°. It also has to have a plastic nose, it can't be connected to ground so a metal nose is a big no no. If it makes contact with ground it will blow up your B channel.

[Harley Hexxe]

Well that's good to know,...sort of.

It's one of those proprietary parts ADA was notorious for.

[Dante]

So I see it's the bridged output that is busted? That's a very special jack and I was never able to find one.
I have all the input and output jacks but not this one. It's actually a mono jack but it has an isolated contact that tells the MT200 switching circuit that a jack is plugged into the bridged out so it will phase shift one output 180°. It also has to have a plastic nose, it can't be connected to ground so a metal nose is a big no no. If it makes contact with ground it will blow up your B channel.

Yup, the bridged Mono output jack. That's why it's not a big problem, I'm running stereo. Not using that jack.

You're correct about that jack - I saw the little contact piece that gets separated as you insert the plug....could not find anything like that online.

Reflowing the solder seems to have helped tho! That amp is now paired with my MP1 Classic, which pretty much stays at home for my personal use....which ain't much. Still, she's been quiet (except for that internal fan )

[MarshallJMP]

I don't think it was a proprietary part back in the day, they just don't make them anymore I guess.

[rnolan]

Hey MJMP, would it be possible to make a "substitute" using a switching socket and an insulating plastic washer thingy?