Hi Peeps:
I have a Signature MPA 3250 Monster AMP ( 3 channel ) I'm curious to know if anyone knows of a source for a "Service Manual" not the owners manual, I have that
. I have an issue with it kicking out when it's cold and suspect the relays or the overpwr trip circuit. It kicks out even when not playing with zero volts in even.
Anyway I'd be happy just to get a schematic.
I contacted Monster and they refered me to a repair center down South. I live in CT. and the AMP weighs in at 92 lbs. Yeah I'm going to ship it to them and back... Thanks for reading.
John Mik
I have a Signature MPA 3250 Monster AMP ( 3 channel ) I'm curious to know if anyone knows of a source for a "Service Manual" not the owners manual, I have that
. I have an issue with it kicking out when it's cold and suspect the relays or the overpwr trip circuit. It kicks out even when not playing with zero volts in even. Anyway I'd be happy just to get a schematic.
I contacted Monster and they refered me to a repair center down South. I live in CT. and the AMP weighs in at 92 lbs. Yeah I'm going to ship it to them and back... Thanks for reading.
John Mik
No documentation ??? WHAT!!!!!!!!
I just got in contact with the "Authorized Monster Amp" repair people and I talked with the one tech that works on these. There is no service manual or schematic available for the MPA2250-MPA3250 great!
He only would point out that noise is generated within and that's what kicks these AMPs out. OK???
Then he said he would have to kill me if he told me ... NOT really.
I'm having a problem with the AMP kicking out when it's cold, no input or whatever input. But it works fine when it gets warmer. Oh well out comes the scope and in we go....
If someone could shed some lite on this PM me please.
Thanks peeps.
John Mik
I just got in contact with the "Authorized Monster Amp" repair people and I talked with the one tech that works on these. There is no service manual or schematic available for the MPA2250-MPA3250 great!
He only would point out that noise is generated within and that's what kicks these AMPs out. OK???
Then he said he would have to kill me if he told me ... NOT really.
I'm having a problem with the AMP kicking out when it's cold, no input or whatever input. But it works fine when it gets warmer. Oh well out comes the scope and in we go....
If someone could shed some lite on this PM me please.
Thanks peeps.
John Mik
I see lots of these with the same problem. Have to turn on several times, or won't turn on. Maybe a current-inrush limiter, or soft-start circuit? Protection system? Maybe self-latching relay? Maybe the main rail filter caps are about gone and it sucks too much current at start-up?
Anyway, if you find out...please let me know! Cascode VAS, ballanced/symmetric, FET outputs, almost sounds like a Nelson Pss design but it's really dedigned by Richard Marsh. Good quality caps etc. Look at this: Marsh Sound Design ~ Experience the Sound with Marsh Sound Design Products !!!
and notice on the main page of the Marsh Sound Design website, what amp is he using in his personal system?
Anyway, if you find out...please let me know! Cascode VAS, ballanced/symmetric, FET outputs, almost sounds like a Nelson Pss design but it's really dedigned by Richard Marsh. Good quality caps etc. Look at this: Marsh Sound Design ~ Experience the Sound with Marsh Sound Design Products !!!
and notice on the main page of the Marsh Sound Design website, what amp is he using in his personal system?
uh, I think it's a 2250 in the pic. And they run hot, but I doubt they're biased as high as a Pass would be. Still... When they were discontinued they were discounted from $2999 list to $700 clearance new. So used they're the same as a 2250, with an extra channer for free, and anywhere from $450 to $1700. I got mine with a turn-on problem for $205 on eBay.
Found the problem with my 2350. But it's not techincally really a "turn-on' problem. Nothing on my front panel works, but the amp still works without a front panel even plugged in. Displays are all '7' and buttons don't work.
Turns out that the 3 heavy toroidial transformers are eaach mounted with a bolt thu the middle. The bolt is a bit long. In transport, if it's shipped sitting o its face, the weight of the transformers causes the bolts to scratch thru the traces of the display board. Might be repairable, assuming it was powered down when the damage occured (which is likely). Yep, damage at 3 places, each lines up with a x-former mounting bolt...
Turns out that the 3 heavy toroidial transformers are eaach mounted with a bolt thu the middle. The bolt is a bit long. In transport, if it's shipped sitting o its face, the weight of the transformers causes the bolts to scratch thru the traces of the display board. Might be repairable, assuming it was powered down when the damage occured (which is likely). Yep, damage at 3 places, each lines up with a x-former mounting bolt...
MPA3250
Well to just follow up on this problem. Got a schematic and I scoped out the unit I have and the protectection stuff is quiet. So I started moving stuff around one day and hooked up my Kenwood KT-8300 FM tuner directly to the amp from the variable outputs. Turned amp on and still kicked out some. Turn tuner on and problem is gone with an input. Tuner first amp on 2nd no problem. hmmmm...
So took a wire and grounded the 3250 chassis to my Kenwood KA-9100 chassis which I use as a preamp and run all sorts of stuff into the inputs. Everything works now. Seems that this puppy (at least the one I have is sensitive to gnd noise or whatever) needs more gnd connect than just the shield of the cables. Plus running old vintage stuff with no third wire gnd and new stuff with it, seems to cause problems (sometimes).
So now from a cold start all is well in stereo land for now. Until my next configuration change.
Man this stuff is fun.
Later
John
Well to just follow up on this problem. Got a schematic and I scoped out the unit I have and the protectection stuff is quiet. So I started moving stuff around one day and hooked up my Kenwood KT-8300 FM tuner directly to the amp from the variable outputs. Turned amp on and still kicked out some. Turn tuner on and problem is gone with an input. Tuner first amp on 2nd no problem. hmmmm...
So took a wire and grounded the 3250 chassis to my Kenwood KA-9100 chassis which I use as a preamp and run all sorts of stuff into the inputs. Everything works now. Seems that this puppy (at least the one I have is sensitive to gnd noise or whatever) needs more gnd connect than just the shield of the cables. Plus running old vintage stuff with no third wire gnd and new stuff with it, seems to cause problems (sometimes).
So now from a cold start all is well in stereo land for now. Until my next configuration change.
Man this stuff is fun.
Later
John
Well my two 3250's are still sitting on a shelf. All channels work, but one has the same issues turning on, but works fine when it does go on. It may well be like that from new, it seems just very sensitive. The other needs the front panel, at the least. Each channel has its own on-board power supply, and all 6 of those power& amp-channel boards work fine. So I might just part out the boards for $100/each channel.
Hello John, you gotten this schematic online or thru Monster ?
Could you share on how to getting one.
My MPA-2250, does have a grounding bolt, which when saw did not understand why was there, for the power cord is of very good quality, and its already grounded.
I will find a way to also use this, to see if makes a difference, hooking up this extra ground.
Problem with my unit is strange one. Sometimes it will power cycle when turn on, sometimes will not, then it could play normal for like 2 hrs., then would power cycle on and off for a number of times, at this point I would turn off the amp. All this happening having an input attached or not, or the speakers connected or not.
I don't have my good speakers hooked up any more until if able to find a repair. I have a pair of old car woofers attached, for these are not easily destroyed, and if did, would not be a big loss, but my main speakers would be a main loss, if was to blow any driver, especially the tweeters, which are the most fragile. Thanks, Ilson
Could you share on how to getting one.
My MPA-2250, does have a grounding bolt, which when saw did not understand why was there, for the power cord is of very good quality, and its already grounded.
I will find a way to also use this, to see if makes a difference, hooking up this extra ground.
Problem with my unit is strange one. Sometimes it will power cycle when turn on, sometimes will not, then it could play normal for like 2 hrs., then would power cycle on and off for a number of times, at this point I would turn off the amp. All this happening having an input attached or not, or the speakers connected or not.
I don't have my good speakers hooked up any more until if able to find a repair. I have a pair of old car woofers attached, for these are not easily destroyed, and if did, would not be a big loss, but my main speakers would be a main loss, if was to blow any driver, especially the tweeters, which are the most fragile. Thanks, Ilson
Here's a file link for the schematic. I am clearly terrible at responding to PM requests for this schematic.
filehosting.org | Download | A3250 SCH REVD.pdf
filehosting.org | Download | A3250 SCH REVD.pdf