ADA Depot - A Forum To Support Users of ADA Amplification Gear

ADA Preamps => MP-2 => Topic started by: bzaneus on August 22, 2020, 08:15:46 PM

Title: ADA MP2 Possible Bad Input Jacks
Post by: bzaneus on August 22, 2020, 08:15:46 PM
I've been using my MP2 in my rack setup for awhile now and noticed that in the last couple weeks, sound will cut in and out, sometimes even kill out. What seems to fix it almost everytime is gently wiggling the cable, so I'm almost certain it's the input jacks (it does this on the front and rear input jack btw). It might be weakened solder joints since it is around 30 years old, but I thought I might get an expert's advice on here before fiddling with it.

Thanks, Zane
Title: Re: ADA MP2 Possible Bad Input Jacks
Post by: rnolan on August 24, 2020, 02:15:55 AM
Hey Zane, the good news is that the input jacks are (sort of) normal switching jacks and not PCB mounted like MP1s so changing the jack is easy.  I changed the front input of my MP2 along the way (as I bought it new 25 years ago).  It is the jack that gets the most ware over time.  The jack you need has a slightly longer thread (shank?) to be able to fit through the case/front panel.  MJMP told me the switchcraft part number years ago (it may be in another post ?).  I've never used the rear jack so haven't had any issues with it.  The front jack did start to play up as you describe so I changed it out.  You can also give it a clean with some contact cleaner but they do ware out eventually.  I'd take the lid off for cleaning and make sure you clean the switching contacts (front and back).  Ideally though just put in a new one (back as well).  Another part to clean are all the push switches on the back panel for selecting cab sim stuff and loop level.  I've found they gum up a little over the years.
@MJMP, what's the switchcraft part number for MP2 input jacks and is the rear the same as the front??
Title: Re: ADA MP2 Possible Bad Input Jacks
Post by: bzaneus on August 24, 2020, 09:28:12 AM
I've popped the lid on it quite a bit and the rear input jack is one of those British style input jacks while the front is the standard. Since I've acquired other rack units for my setup I've been using the rear one, at the moment I want to know if Marshall might know a part number on it. In the mean time I'm gonna clean and solve the contacts and see how that works out
Title: Re: ADA MP2 Possible Bad Input Jacks
Post by: MarshallJMP on August 25, 2020, 01:01:43 PM
The rear one is a standard cliff jack with 4 solder lugs, the front is a switchcraft L12A (you need this exact type !!!!)
Title: Re: ADA MP2 Possible Bad Input Jacks
Post by: bzaneus on August 26, 2020, 08:57:58 AM
Appreciate it Marshall