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

ADA Preamps => MP-2 => Topic started by: 2handband on November 23, 2015, 04:35:17 PM

Title: Reconditioning an MP2
Post by: 2handband on November 23, 2015, 04:35:17 PM
I picked up an MP2 a couple of years ago and started gigging with it immediately. It had a couple of minor issues that I chose to ignore, but some other things have gone wrong and I like the unit enough that I'm going to recondition it. Here's the bucket list:

There's a dead spot in the compressor; some of the presets that use the compressor don't work at all until you turn it off. To address this issue I'm ordering an SSM 2120 dual vcm chip.

Output A works on startup but dies soon after. Not sure what the problem is. Output B works fine.

The noise gate jitters. Seems that's a matter of replacing a resister.

I'm gonna put the noise mod in.



In case anybody is interested I use it with a Peavey Classic 60/60 power amp and a homemade 2x12 with classic lead 80s. Fx is a g major 2 and the guitars are mostly Firebirds.
Title: Re: Reconditioning an MP2
Post by: rnolan on November 25, 2015, 04:43:06 AM
Hey 2handband, absolutely :thumb-up: we're interested, I assume you are running the GMaj in MP2 loop?, if not, it will sound better than chaining through the GMaj to your power amp (maintains the analogue signal and mixes in the FXs) BTW I've tested this assertion and it IS better (TC GMaj has no analogue pass through, first thing it does is A/D the signal).

MJMP can (no doubt) help more with the compressor (and there are other posts about this) and, A output issue, somethings getting hot and failing (seems to me?).
Noise gate jitter is a resistor (R611) See attached.
Noise Mod is 1 resister (R913, the main culprit) and 21 CAPs, minimum do R913 (so above R913, see attached noisemod.pdf, measure chassis/earth to test point (on photo), should be 190v or in my MP2s a it's little less (~187v), above 190v causes problems).  MJMP can sell you a noise mod kit with all the right bits of the best components just PM or email him.
Also worth changing the input jack while you have it open (too easy and it takes the most wear and tare).  It's a longer thread than normal jacks, again I got MJMP to send me a bunch for my MP2s, but he can tell you the switchcraft part number you need. 
Title: Re: Reconditioning an MP2
Post by: vansinn on March 01, 2016, 11:22:50 AM
I would start with replacing every electrolytic capacitor - not just the ones in the PSU section.
The compressor chatter could very likely be related to a capacitor being enough down in value, so that the attack timing gets skewed.
I have no directly useful info on the other problems, but capacitors are my main hurdle in life.

A Bit like with computing.. if not working, check the PSU. Still not working, check the cabling, then the routing. And check the routing again, just in case.. :lol: