ADA Microtube 200

[rnolan]

Hang in there Skitzo, between MJMP and Sparker, they'll help get you through it.  Maybe the electronics teacher where you work can help you, or you could give it to a competent tech to fix for you.

[GonadiusPrime]

An old soldering gun and a little of your time is all it will take.  The procedure MJMP speaks/types of is really easy to do.  The schematics and layouts on this site will help out.  Good luck man.

[Skitzo]

Well I have the specs I just need to know what's what.  What to pull off to swap out.  It seems like one side is actually working. Everyone here has been so helpful. It's now a question of identifying the part and finding the replacement. If I swap out all kinds of parts I'm afraid ill bust something - so one at active may be the ticket. 

[Dante]

Swap out one part at a time, test it after every step.

[MarshallJMP]

Normally i advise people to change one thing at a time but in this case you need to change them all in one go.
Problem here is you don't know what is busted.If you replace the wrong one (one that works) the bad part can destroy the other one.Let's say you have a bad driver and you leave it in,and you just replace the power mosfets,that bad driver WILL destroy the 2 powerfets.That's why i say replace everything,this way you are 100% sure everything is new and in working order.

[Skitzo]

My feeling is that it is the MOSFETS but ya, I agree swap them all out.  I just still need to find where I can get the parts. Ugh

[GonadiusPrime]

I think I ended up going to DigiKey because they're kind of local.  Bought each component in lots of 10...I think.  The parts aren't hard to find, or at least they weren't.

[GuitarBuilder]

I don't want to sound contrarian, but asking a non-experienced person to replace the MOSFETs is pretty high risk.  I think Skitzo would be much better off taking it to an experienced amp tech with the information/schematics gathered here.  He'll have it back in working order in no time.

I had a Microtube 200 with the same symptoms (one dead channel) and it ended up needing two resistors replaced as well in addition to one of the MOSFETs.  It took me multiple hours of troubleshooting with an oscilloscope to figure it out.

[rnolan]

Hey Skitzo, tend to agree with GB here, if you're not comfortable (hey, if you are, DIY), or, get a tech to do it for you (that's why god invented techs...))

[Skitzo]

Honestly, it's not worth sending out.  The only reason why I'd fix it is to simply gain some experience in fixing amps.  It'll cost most than the thing is actually worth and I was given it anyhow.  I have a 300 w dual channel TOA amp I'm using now.  So if I could somehow figure out which MOSFET - ill give it a go.  I now have a little more electrical gear. 

[MarshallJMP]

Skitzo,mail me,we'll figure something out.I'll get to you on monday.