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

ADA Preamps => MP-2 => Topic started by: gb on April 11, 2014, 03:26:57 AM

Title: mp2 output problems
Post by: gb on April 11, 2014, 03:26:57 AM
I love my mp2 but recently this has been happening sounds like its farting out the speakers with no drive..on xlean it sounds worse.. I narrowed it to the mp2. Ive tried different tubes leads etc.. and its something in the mp2. If I leave it on long enough it slowly comes good. If I turn it off and on a few times it comes good.  Now every time first turns on it has this issue..

Dont mind my crap playing while holding the cam.. just to show what its doing

Hope its fixable..im sooo bummed

https://www.youtube.com/watch?v=dmKWCXhgRrc&feature=youtube_gdata_player

Heres is when it came good.. same patch

https://www.youtube.com/watch?v=i96CHwCjGTs&feature=youtube_gdata_player
Title: Re: mp2 output problems
Post by: MarshallJMP on April 11, 2014, 04:12:09 AM
Is the compressor on in this preset?
Title: Re: mp2 output problems
Post by: gb on April 11, 2014, 04:25:14 PM
Is the compressor on in this preset?

Compressor is set to OUT but makes no difference if I change it. This issue is on alll presets.

Title: Re: mp2 output problems
Post by: gb on April 11, 2014, 04:33:22 PM
Ok I noticed when I change the wah filter from OUT to IN on PEDAL it came alive instantly.  I change it back to OUT it has that problem again. . After a few times of changing it it works both ways.

Also I dont have any midi or effects loops plugged in.. just guitar into mp2 and output to poweramp.
Is that any clue?
Title: Re: mp2 output problems
Post by: MarshallJMP on April 12, 2014, 05:39:31 AM
Well the compressor and wah can give some problems,usually it's the compressor.Now in your case it seems to be a switching problem.The switching is done with fets controlled by U202 (TC9164).What you could try is gently get the U202 out (it's in a socket) and put it back,could be a bad contact.
Title: Re: mp2 output problems
Post by: gb on April 12, 2014, 04:30:23 PM
Well the compressor and wah can give some problems,usually it's the compressor.Now in your case it seems to be a switching problem.The switching is done with fets controlled by U202 (TC9164).What you could try is gently get the U202 out (it's in a socket) and put it back,could be a bad contact.

Found it.. its in an awkward spot but gently removed and popped back in and still no difference :(

Any ideas.. ?
Title: Re: mp2 output problems
Post by: gb on April 12, 2014, 04:34:49 PM
It also appears if I just leave it as is it comes good afyer 5-10mins.. but the wah IN instantly works on first turn on..
Title: Re: mp2 output problems
Post by: cheachwood on June 05, 2014, 05:33:18 AM
Hi gb,

Did you resolve your problem?
I have the same for months (not to say years) and no one could resolve my problem, I have to wait every time until all comes good. I am very disappointed because I don't use it anymore in live.
Sometimes My MP-2 stops working and I must wait more than an hour to get it back.
If somehow can help us it would be great.
Title: Re: mp2 output problems
Post by: rnolan on June 05, 2014, 07:17:37 AM
Hey cheachwood, I feel for you, and lately, I've been pondering what the f$$k I'd do without my MP2 (it's been so reliable but it getting old...).  While you try to sort out what's wrong with it (and you could send it to MJMP in Belgium ??), you could buy a another MP2 (or 2.) to tied you over.
Title: Re: mp2 output problems
Post by: gb on July 14, 2014, 11:44:30 PM
Sorry cheachwood I didnt see you're reply. Ive stopped recieving email alerts from the forum for some reason.

No I havent. Im the same as you. Itis disappointing to be honest bcause if I was confident it was reliable this would be my ultimate preamp!!.. I love it and its versatility.  But I cant wait for it and to come good in a live situation.

Mine appears to be an issue with the wah switching.  If I switch the wah IN it works fine but wah OUT I have o wait for it to come good. It will cost too much to send to marshalljmp.

Are these chips available to buy to replace. ?? Assuming thats the issue. Ive reseatd mine a few times and no change.

Migh have to find a broken one to get the part which is rare!!
Title: Re: mp2 output problems
Post by: MarshallJMP on July 15, 2014, 04:11:27 AM
Well this is a known problem with mp-2's.Usually it's the compressor switching,but sometimes it's also the wah that is giving this problem.I've been looking for a solution for this but i haven't found what is causing this problem.I have 3 mp-2's and they also have this problem but all 3 with the compressor.I already replaced all components that do the switching and nothing seems to help.Don't know what to do anymore.
Title: Re: mp2 output problems
Post by: rnolan on July 15, 2014, 07:29:57 AM
Hey MJMP mine (2 x MP2s are still ok touch wood..), WTF is happening ? Can I help the thinking here ? well it's got to be something coz it used to work... What else could it be if it's not the switching ????
Title: Re: mp2 output problems
Post by: MarshallJMP on July 15, 2014, 09:09:18 AM
Well it's very strange,i get a signal on one end of the switching fet but not on the other side,don't know why and the strange thing is it goes away after a few minutes with mine and everything works fine.But i know with some people it take up to an hour.
Title: Re: mp2 output problems
Post by: gb on July 15, 2014, 03:28:04 PM
Allll hope is lost haha.

Oh well one day you will find it.
Title: Re: mp2 output problems
Post by: rnolan on July 16, 2014, 05:29:57 AM
Could it be an issue in the PCB ? hairline crack in a track ? something that's gets better when warmed up ?
Title: Re: mp2 output problems
Post by: MarshallJMP on July 16, 2014, 11:46:35 AM
Well R that's good thinking but no that's not the problem.For some reason the signal is not comming trough the FET altough it should.
Title: Re: mp2 output problems
Post by: rnolan on July 20, 2014, 07:34:07 AM
Hey MJMP, pls pardon if I ask dumb questions BTW or stuff you've already thought through.
Does the signal come through the FET when its not in the ADA circuit ? (i.e. isolated)
If FET is good, what could change its behaviour ?? I'm a bit out my league here, my basic understanding is it's operating as a switch (on/off) ??
Also, they used to work fine (and still do in many MP2s) so where's this going...
Maybe the solution is a new switching circuit ?
Cheers R
Title: Re: mp2 output problems
Post by: cheachwood on February 09, 2015, 02:07:52 AM
Hi all,

OK PROBLEM SOLVED!!!
YEEESSSSSSS!!!

After years of investigation, questions, etc. I met a guy here in France and in my town (Nantes) who repairs guitar amps, in fact he was a friend of mine years ago and we losted ourselves until all those years. Recently, in decembre, we met us in a music store in Nantes and we began discussing of what we did all thoses years, so he began to say that one of our friends is now reparing tube amps, preamp, etc... So I talked about the issue on my MP2 and he accepted to see what he could do.

After 2 months of investigation and test, he finally solved the problem, so he changed ALL the transistors and diodes on the compressor circuit and now my MP2 is sounding like the first day!!! He said me that the initial transistors were not good quality so this was the source of the problem and very difficult to see.

Here is his site for people who wants to contact him : http://pms.elec.free.fr/topic/index.html

YEESSSSSSS!!!!!

Cheachwood
Title: Re: mp2 output problems
Post by: rnolan on February 09, 2015, 03:02:35 AM
Hey cheachwood, woww what great news  :whoohoo!: and thanks for the contact !!
Now we/you can get on with MP2 tone/patch/patching to get it sounding the best it can for you.
Cheers R
Title: Re: mp2 output problems
Post by: MarshallJMP on February 09, 2015, 06:18:13 AM
Nice!! Do you happen to know if he used replacements and if so which ones?
Title: Re: mp2 output problems
Post by: RobbHell on February 09, 2015, 10:36:04 AM
Awesome news! what replacement parts did he use?
Title: Re: mp2 output problems
Post by: cheachwood on February 09, 2015, 11:31:31 PM
Awesome news! what replacement parts did he use?

I don't know, he said to me that he replaced all the transistors and diodes of the compressor circuit board.
I will ask him by mail and keep you in touch.

Cheachwood
Title: Re: mp2 output problems
Post by: astrobushido on September 07, 2019, 11:07:01 AM
Hi guys, unfortunately one of my MP2's seems to be having exactly the same described behavior, as showcased in Gb's youtube videos.

Cheachwood, did you get any answer about the transistors and diodes replacement parts?

I looked around the site you indicated but  :( (bad luck) the workshop is closed until 3 october.
Title: Re: mp2 output problems
Post by: vansinn on September 09, 2019, 02:43:21 AM
Interesting and annoying trouble-shooting.  Glad the culprit got fixed ;)

Due to this, I just wrote a little essay about basic maintenance and scooping-up electronics:
http://adadepot.com/index.php?action=post;board=17.0 (http://adadepot.com/index.php?action=post;board=17.0)
Title: Re: mp2 output problems
Post by: ang3lus on April 22, 2023, 12:12:19 PM
managed to contact the tech in france and he sent me this

"
Hello, first of all, please excuse me for my American, I use a translator.
The ada mp-2 repair is quite old and I’m not sure what information I’m going to give you.
As a reminder, I had replaced the following transistors: Q200,202,220,and 221.
I think I have also replaced diodes D206 and 208.
I hope this will help you repair your equipment. I also attach the part of the diagram.

Best regards

Patrick
"

what transistors can i use as alternatives for the ones listed ?
they seem to be out of production and i cant find equivalants
Title: Re: mp2 output problems
Post by: MarshallJMP on April 23, 2023, 12:12:57 PM
Already tried this, didn't help with my MP-2.