mesa boogie m6 carbine schematic

[EDWARDEFFECT1]

where can i get a schematic for this amp. it powers up but no sound. i found 2 bulged  47uf capacitors and replaced them along with 2 bad ic.i have signal to the output board  jumper wire now but nothing after that...thanks...

[joecool85]

Not sure on the schematic but if you take some good pictures of the PCB we should be able to help you out.

[EDWARDEFFECT1]

GOT THE AMP WORKING IT HAD  BROKEN TRANSISTOR LEADS.THE 10K RESISTOR NEXT TO THE TRANSISTOR WAS GETTING HOT.I JUST PUT THE TRANSISTOR IN THE AMP AS I HAD TO WAIT FOR BACKORDERED RESISTORS.THE AMP HAS A 10K 3.75 WATT WIREWOUND.MOUSER SENT ME 10K 3 WATT RESISTORS AS THAT IS ALL THEY HAD.IT DOES SAY ON THE SPECS IT IS GOOD TO 3.75WATTS ,SO I'M PROBABLY OK. I'LL HAVE TO TAKE THE AMP APART AND SEE WHATS GOING ON.HOPE THAT THE RESISTOR WAS WEAK AND IT ISN'T A DESIGN FLAW.POSSIBLY THEY HAVE UPDATED THERE CIRCUITS ON THEIR NEWER MODELS. THIS IS THE SECOND TIME THIS AMP HAS BEEN DOWN SINCE IT WAS BOUGHT.SOUNDS GREAT WHEN IT WORKS.WILL KEEP YOU POSTED.....

[J M Fahey]

Congratulations.
Your 3W one should work, although somewhat hotter of course.
If it's in the path of some wind flow from the fan, you'll have no problems.
*IF* someday you get the schematic (keep asking the Mesa guys, including amplifier serial number so they see it's a legitimate demand), please share it here for the comon good.

[teemuk]

Agreed. I've never seen any of the Mesa/Boogie schematics for non-tube stuff.

[EDWARDEFFECT1]

 heres one for the pros!!!i replaced the 3.75w 10 k resistor on the output board.it was getting hot due to a transistor having broken legs. someone previous to me must have gave it the push test and broke a couple of legs. i replaced the transitor only as i didn't have a resistor at the same time i replaced the transitor.the resistor still checked good at 10k.the amp worked for a bit.then was hooked up to a single extention chord with the rest of an entire bands equipment.i guess a couple of other elcectronic items the band was using had problems also. the amp sounded good at the sound check then had noise and lower power so it was replaced with a different amp for the rest of the night. the amp was taken apart again and the 10 k resistor was replaced with an exact replacement 10k 3.75w wirewound.everything checks out component wise ,but the resistor get hot 300 degrees plus when checked with a infared temperature gage.it also has 90v+ on one leg and  -89.7v on the opposite leg. i notice there is a trim pot on the board would it have anything to do with the heat or is it just for biasing the transistors.is it possible that the 10k resistor is an isolation resistor?wondering if mesa did any upgrades possibly a 5w 15k resistor or something larger.possibly a design flaw.where to go from here.any ideas...thanks....ed

[J M Fahey]

180V DC leg-to-leg translates into 3.25W being dissipated in it.
Within limits but it sure will be hot, so that seems normal.
Without the schematic, specially being an unconventional amp, we can advance no further.
Call, write, EMail, send smoke signals, message pigeons, whatever, (or everything at the same time), in sum, become a PITA to the Mesa guys until they send you a schematic and preferrably a service manual too.
Do not touch any trimmers at all because we have no idea about their functions.
Post a couple sharp well illuminated pictures of the amp guts.
Preferrably in the outside, in a bright cloudy day or when a cloud just covered the sun itself.
If you live in the middle of the Arizona desert or a similar cloudless place, put it under a gazebo or an equivalent piece of white cloth , curtain material, whatever, to diffuse the light.

[EDWARDEFFECT1]

not a mesa dealer no schematic.they have made changes in the circuit in question. he told me of a couple of parts they changed but wouldn't give any other information except sorry we can't let you change the parts. send it back to the factory....now a 15 minute job for me is going to turn into a 30 day wait for the amp!don't forget it's on the opposite coast. wish i could of helped with a schematic or service manual. i would of been helpful instead of a pita...thanks for everyones help!my good friend and tv repairman of 40 years big jim gave me the sugestion to raised the resistor off the board to cut down on heat radiating to the circuit board and the ceramic cap and resistor in front and back of the 10k wirewound.guess they must of herd you jim!!!...later....ed

[J M Fahey]

OK, just don't get crazy over it, it's not worth it.
Let your customer send it to the factory and support all expenses, delays and troubles.
You've done your best. :tu:

[eaelec]

I had one of the early ones (the Fathom) before they renamed it come into
my shop for repairs. The problem was that 10K 3.75 watt resistor mentioned
above had damaged the PCB by repeated heating (and cooling when it gets
turned off ) so one of the copper tracks had a hairline break in it. The resistor may be designed to work at 175 degrees C, but the PCB is not.

[Roly]

not a mesa dealer no schematic.

-1 to Mesa-Boogie for being anally retentive about service information.    :duh

There is no real justification for this attitude, it's just customer indifference.   :grr

Edit to add: checked a dozen circuit sites and no sign I afraid.

[Enzo]

As a professional repair guy, I don't like that policy any more than you do.  But it isn;t indiference to the customer.  Each company is different, but I think such close-to-the-vest policies are born of protecting the ignorant as well as the company reputation.

We both like helping people, that is why we post here.  But I learned a lesson once when a guy asked me for advice fixing some amp, and I told him to check the plate voltages.   He then asked, "Is the plate that metal part it is bolted to?"   Lesson is: you never know who you aretalking to and what they know.  And in this day and age of the internet, there are tons of people who can throw the technical jargon around yet know nothing.

A company can decide not to pass out drawings because doing so is giving tacit approval for the recipient to work in the amp.  A potentially lethal experience.  Some companies don't want such exposure.

There are not many of them, but Mesa does have authorized service centers as well as independent shops they will refer customers to.   Very few customers ever try to do actual repairs themselves, so the shops provide a means of service.

And another reason is that when someone tries and fails to fix their amp, many times they will say "Crappy Mesa amps,  they don;t work."  People rarely blame themselves.

Not an exhausstive list, but some of the reasons such policied exist.

[Roly]

Oh I well understand their reasons Enzo, I just don't think they hold water.  Just take Fender for example, the circuits for most of their valve amps are in wide circulation, but have any of these dire concerns come to pass?  Has Fender's reputation suffered on that account?  Or is Mesa's real reason trying to stitch up all the service work for themselves?  I've encountered this sort of thing on many occasions, "industrial secrets", and it always turns out to be self-defeating in the end - the policy itself damages their reputation.

I'm sure that like me one of your primary concerns is making sure that a working musician has his tools of trade when they need them, and I don't see that concern reflected in this sort of company policy.

[Enzo]

I'm sympathetic, but it comes down to how each company thinks about it, not whether some other company succcessfully does it.  Peavey is king, they send anything to anyone.   Fender will generally dole out what you ask for.  We find it ironic though that Fender schematics have a non-disclosure statement on each drawing, yet they include the drawing inside the amps. Behringer is the other end of the scale.

Peavey will sell anyone any part.  Fender will not sell parts, they will direct you to their dealers or other autorized part sellers.  Has that hurt their sales
?  Maybe not in a measurable way, but trust me, people DO gripe about it.

But we as service people sometimes say "Oh that brand is not serviceable, they won;t hand out schematics."   But that ignores that said brand provides a network of service centers to provide that needed service.  Just might not happen to be one of US.

No, Mesa is not trying to hog all the service work.  Service is a vastly tiny portion of their business.  If they sell two amps, they have profitted more than a bench tech could bill in a week doing fix-its.