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Let's Get Technical => Power Amp Tech => Topic started by: Dante on January 12, 2019, 08:43:11 AM

Title: MicroTube 200 issues
Post by: Dante on January 12, 2019, 08:43:11 AM
Hi Guys,

I though I was having trouble with my MP-2, or a bad cable, but it turned out to be my MT-200. I was using the bridged mono jacks, practicing at home (thankfully) and the volume would jump up occasionally. Little spurts of extra volume. It was strange. It could also have been that I was playing with it in a 'messed up' state and those volume jumps were the actual normal volume.  :dunno:

Anyway, I switched to using Channel A with a smaller speaker cab and all was well....until now. It seems the cancer has spread to channel A now, and channel B. Shit.

I'm gonna yank it outta my rack today, what should I check first?
Title: Re: MicroTube 200 issues
Post by: Kim on January 12, 2019, 10:50:25 AM
As it turns out, I too need to do a complete shakedown of my rig for a very similar problem.    :facepalm:

But since you've already narrowed the problem to the MT200, I'd suggest a good cleaning of every pot and jack in it first.   If there are switching type jacks, make sure to clean those switching contacts as well.   Always hit the Easy Stuff first....   :)
Title: Re: MicroTube 200 issues
Post by: Kim on January 12, 2019, 10:55:06 AM
And then there's this tidbit of info:

My MT200 freaks out (http://adadepot.com/index.php?topic=1801.0)
Title: Re: MicroTube 200 issues
Post by: Dante on January 12, 2019, 05:45:38 PM
I read that already...but I didn't know if what I have is a 'burp'
Title: Re: MicroTube 200 issues
Post by: Kim on January 13, 2019, 09:01:16 AM
That reference was mostly for the chip replacement info should you require it I guess.   

But last night I just went through and cleaned every single jack, switching contact, and pot in my entire guitar chain (MP-2, Intellifex, Classic 60/60) chasing exactly what you've described.  Success!   No more volumes spikes and no more static.   :whoohoo!:

Again, E.S.F.   Check the Easy Stuff First.   :thumb-up:
Title: Re: MicroTube 200 issues
Post by: Dante on January 14, 2019, 06:39:38 AM
Hmmm... I guess I'll start with the jacks. What's the best way to clean them? Just spray with deoxit and insert a cord 1,000 times?

While I'm inside, should I stay away from any big parts that might knock me across the room?

What else can I check while I'm in there? I'm going to look for swelling caps, discolored bits, and then flip it over to see if any of the solder needs re-flowing (I guess). Any advice would be greatly appreciated.
Title: Re: MicroTube 200 issues
Post by: MarshallJMP on January 15, 2019, 01:57:38 PM
Leave it off for a few minutes before you open it. For the rest Kim has a point with ESF , if that doesn't help you can go in deeper.
Title: Re: MicroTube 200 issues
Post by: Kim on January 16, 2019, 01:40:12 PM
Hmmm... I guess I'll start with the jacks. What's the best way to clean them? Just spray with deoxit and insert a cord 1,000 times?

1,000 times seems a bit overkill.  998 times would be more appropriate.   ;)   
But seriously, if you need a number......10 is fine.    Spray into the jack and/or on the male 1/4" plug and give it to it.  I can't remember for certain if those jacks are enclosed (but I think they are) so the switching one will be hard to get at the switch contacts.  Best you can do there then is just blast the cleaner into the jack and hope it gets there with the repeated plug inserts.  Also there's an internal cover to remove in order to get at some stuff.  You'll see it when you open it.

And while you're in there, see if you can spray into the front panel pots.  There should be a little access notch or hole to get the spray into the assembly.  Give it a shot of spray and work the knob around.  Then I'd say if you don't see anything obviously wrong in there, button it back up and try it out.     Good luck, we're all counting on you.   :)
Title: Re: MicroTube 200 issues
Post by: Dante on January 16, 2019, 01:53:52 PM
Good luck, we're all counting on you.   :)

wow, the pressure is intense

I sprayed the jacks with deoxit and inserted a cord about 998 times last night, I did the knobs as soon as I got it, and have had no issue with scratchiness, so I left them alone. Gonna plug it in tonight and try it out. It usually takes a good half hour of playing before it acts up...