mp2 comp on no sound

[jnelson]

I talked to jmp about this issue years ago, but ended up moving around a lot and never got back
to following up on it
you turn compressor on and it mutes the unit, turn it off and you get sound but cannot use comp
any idea's 
really would love to get it back up n running ,
also I have a pair of mp1's I'm looking to get in touch with jmp but it seems his old site isn't working
the e mail address is incorrect, not exactly sure on that one, starts with phillipe if anyone knows about
it.
thanks for any help.
John

[rnolan]

Hey John, MJMPs email is in his profile (click on his name in any post he's posted to).  His web site is working for me (http://www.marshalljmpmodshop.net/index.htm)

Cheers R

[MarshallJMP]

I'm still alive 

Just send you a PM with my email address.

The compressor thing is a known problem with the mp-2, usually if you wait some time it will start to work. Sometimes it takes a minute, sometimes 30 minutes.

[rnolan]

There's also a related (maybe) issue where you get no output at all unless you start the unit with a patch that includes the compressor, ie when you power down make sure the current patch has compressor on so when you power on again, that patch is loaded.  One of my units did this, though seems ok now after the noise mod.

[jnelson]

so still no fix for the problem?  ok I plan on getting my old rack out soon and trying it again to see if it works, will update as soon as I check it out.
planning on doing at least 1 of the mods JMP has for sale to one of my mp1's as soon as I get a chance, I have not played guitar since my dad
passed away several years ago, not exactly sure why.. just happened, but am trying to get back into it and man it sure is different after taking such
a long break !
thanks for the help guys, cannot thank you enough !
John

[rnolan]

Let us know how you go, condolences BTW  :facepalm: , I know the feeling.

[MarshallJMP]

Well it seems to be a thermal problem, with mine if I heat up the area where the switching fet's are it works. At least with one of my MP-2's.

[rnolan]

Hey MJMP, This is an interesting area...  seems to be age related (in one sense) but I have 4 MP2s and they are all fine (2 with noise mod, 2 stock), as Julius Sumner Miller said (if anyone remembers him) "why is it so  :dunno: "

[MarshallJMP]

Well 2 of my mp-2's have this problem, the others don't.

[rnolan]

Do you think it may be component related ? as in a batch of whatever bit(s) have gone off over time and they were only in a run of units  :dunno:

[vansinn]

Never had that issue myself, but given how damn hot both the Analog Devises dual compandor and associated opamp runs due to +/- 24 volt rails, I'd start looking at those two chips.

[MarshallJMP]

No it's a problem with the switching. It's the FET/ diode.

[vansinn]

The engineer has know-how; the university-educated has know-why
Careful, when arguing against superior knowledge..
;)

[MarshallJMP]

The engineer has know-how; the university-educated has know-why
Careful, when arguing against superior knowledge..
;)

  Well did some work on this problem before, so I know where it is, don't have a solution yet.

[jnelson]

you don't happen to have one laying around that has the issue to replace parts on to see what works do you ?  just curious.
still haven't gotten around to digging the rack out, yea I'm slow, getting back into this is going to be harder than I anticipated grrrr
that and I have plenty of amps laying around etc....
but would like to get the ada stuff running again....
i do have a q on the 3tm for the mp1 though, does one do like the brown sound and
another do like a triple rectifier soundish?
since i have 2 mp1's i have been thinking about doing both of them with different mods
instead of using an axe fx...
John