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Mesa Boogie M9 Carbine and Bass 400+ schematics

Discussion in 'Amps and Cabs [BG]' started by Kartofell, Jan 5, 2020.


  1. Kartofell

    Kartofell

    May 1, 2017
    Hi! I would need schematics for my M9 Carbine and Bass 400+ (6-band EQ). Can anyone help? Thanks!
     
  2. shoot-r

    shoot-r

    May 26, 2007
    Illinois
    It's my understanding from several years back that when I tried to have a Mesa Bass Head serviced at a "Non" Mesa Service Center is that Mesa WILL NOT give out schematics or make spare parts available.
    I contacted a Mesa service center and was told Mesa M-6 and M-9 bass amps (I own two M-6's) and I'm guessing the 400+ also, have to be returned to the Mesa California factory for repairs.
    I'm also guessing again, that Mesa guitar amps can still be serviced at Mesa's authorized service centers.
     
    Last edited: Jan 10, 2020
  3. Kartofell

    Kartofell

    May 1, 2017
    Yes. That's why I'm asking for schematics here (otherwise I'd just wrote to Mesa). Two way shipping for an amp to USA (+repair) is way too expensive. I might as well get a new amp for the price. And 1st authorized service is 500km away from Slovenija (and they are extremely sloppy, so I can't trust them anymore). I have a great tech guy here in Slovenija, I'd just need the schematics as it would help a lot.
     
  4. shoot-r

    shoot-r

    May 26, 2007
    Illinois


    Mesa "(will not)" give out schematics for M-6's/M-9's, or make repair parts available outside the California factory.

    It might be possible a "bootleg" schematic and after market parts for the M-9's might be floating around I guess.

    It is my understanding M-6's/M-9's have to be returned to the California, U.S.A. factory for repairs, (maybe Agehorse will chime in and tell if I was mis-informed.)

    The way it went for me, once I added up repair costs and shipping costs when one of my M-6's was showing signs of needed servicing I opted to put the money towards a class D head.
     
    Last edited: Jan 13, 2020
    Kartofell likes this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Carbines need to be returned to the factory or to certain specific service centers (there are some countries that have a service center that can support these amps, but they are carefully selected).

    The challenge with these amps (and some others) is that over their ~10 year lifespan, there were multiple versions due to parts being discontinued, changes necessary to utilize revised parts, etc. We rely heavily on tracking of the serial number in order to determine where in the production cycle an amp sits, and which revision level it was built to plus any factory authorized updates that were done to the amp. The other problem is that sometimes we see an amp that has had a failed repair attempt by a service tech who was in over their head. When this is the case, there is a LOT of additional work necessary to determine any other damage that was caused, and the costs can grow quickly. Also, the parts costs can be quite high, especially for lateral MOSFETs, we have a limited number of earlier versions that are no longer available, and if we do not have these available the entire set needs to be replaced with the newest version and then the amp needs to be tested and possibly adjusted if there are stability issues. The new parts are nowhere near the same as the older parts. A set of outputs for an M9 (depending on the version) can be a couple hundred dollars alone.

    A call to customer service can help you sort out the best way to address your amp, but you will need the serial number so that we can look at the amp's history (assuming it was repaired through a factory authorized method). I believe the Big Blocks, Titan, and M-Pulse/Walkabout are being handled this way as well, but again it depends on where in the build cycle a specific amp sits.

    Hope this helps.
     
    Kartofell likes this.
  6. Kartofell

    Kartofell

    May 1, 2017
    Thanks for the explanation Aged Horse! I know about the M9 failures, and upgrades, I've heard it many times before (and tooth and nail arguments why should I do it). As I said I'm not looking to do those upgrades, so this is not an issue. It would cost me too much, no matter where I send it, and I hate the fact that the customers need to pay for upgrades, that have to be done, just because the amp wasn't built properly/reliably in the first place. My M9 worked fine for 10 years, so I decided I'm going to risk it further and whatever happens, happens. If it fails, it fails. I'll just get a new amp. +I already own multiple Mesa amps (2x M2000, BB750, M-Pulse 600, M9 and 400+) and some others too.

    My M9's serial is M9-000411 (it was never repaired, works without any problems). But I don't even know if it's 600W or 900W. Would you know this info, and which upgrades would need to be done? As a Mesa fan, I would love to know some more information about my amp. But I would like to rewire it from 240V to 230V. I understand this amp has taps for 230V and 240V, so this can be done easily.

    My 400+'s serial is B1342 (bought it just recently). I would like to do the same with this one, only from 220V to 230V. Does 400+ also have taps for 220V/230V/240V? Would it be possible to get schematics for this one? Thanks!

    PS: Just curious, is Mesa service in Esse music Italy one of those carefully selected service centers?
     
  7. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    I'm not talking about "upgrades", "updates" is a different word with a different meaning. Updates generally refers to to changes that might be required due to the need for repairs where the original parts are no longer available, or have been redesigned and no longer meet the requirements of the original circuit. It may also mean that we discovered something that may affect the long term reliability that was not known (nor could have possibly been known) until many years have passed. We continue to support all of our products for many years longer than most manufacturers do (we still service many of our products made 40-50 years ago where parts are available).

    I don't know what transformer you have in your amps, that's something an authorized service center can research for you.

    Generally, an amp that is specified to operate at 240V will operate perfectly fine at 230V. The problem is that perhaps you do not know for sure what your amps are even wired for, which is why I suggest that you have a service center verify first, then assist with what you are needing (if it's even necessary).

    We do not release schematics to end users and non-authorized service folks because there have been too many misunderstandings that have gone wrong and turned into very expensive repairs. Sorry.
     
  8. Kartofell

    Kartofell

    May 1, 2017
    Well, from what I've heard, many M9's (and also many M-2000's, and Titans blew up in first months of use because of overheating problems). My M-2000 blew up, and two Titans of my friends, very soon after they bought them. A friend sent his Titan back to Esse Music Italy ("official" Mesa service?) under warranty, and they did a very sloppy job, so the amp blew up again as soon as he got it as also blew up all the speakers in his PH810. Then he took the amp to our local tech guy, and it has worked fine since then. Also, when my M-2000 blew up, my tech guy replaced the trafo (he put in the trafo with same parameters but with a thicker wire) and it works without a problem since then, and that was many years ago.

    I got schematics for my M-2000 and BB750 directly from Mesa customer service without a problem, so I don't understand this... Do you release schematics for certain amps only and not for others? This is a total bummer because we don't have a mesa service in our country or anywhere near. I have no other option than my local tech guy really. Shipping an amp to some other country is just too much trouble (and too expensive also). Schematics would help a lot. This is one thing I really don't like about Mesa Boogie. This and reliability. But I love the sound.
     
  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    The Titans and M6/M-9's used an output device that turned out not to be as robust (or as consistent from unit to unit) as their specs suggested. There were wild variations in some production lots and tight parameters in other lots. Ultimately the problems with the device became obvious and the devices were discontinued. We replaced any of these defective products (and updated as needed) under warranty at our cost.

    The lateral MOSFET was a wonderful device with some outstanding characteristics (I used them in some of my earlier products but they were a Hitachi part that was discontinued even earlier, and even with generous design margins I encountered a higher than normal failure rate along with some unexpected quirks) but while they had a unique tone (in part because of the circuits that they could be used in and how they operated), they proved to be less practical in practice than in theory.

    It turned out that the lateral FET production process (silicon foundry process) was ultimately not as reliable as the industry hoped for, the claimed voltage limits were not well defined (some of this was variations within the lateral and even the vertical FET architecture), so for some designs we found that de-rating the device was the only practical solution given that we (obviously) could not change the semiconductor process.

    This occurred with specific MOSFET batches, and the problems often did not show up for several years (as the silicon and other parts around the silicon aged). With the batches without variations there were no problems ever. The problem now is that these parts are no longer available (the process was so challenged that everybody stopped using them) and the last manufacturer (which is not even a manufacturer but a re-packager) making similar parts can not guarantee compatibility with any of the previous parts we used. We have some workarounds, but they are different for each amp, and we have to verify date codes of the devices and see what parts we have available.

    We remain with known good technical service agents in the different regions but some areas of the world are more limited than others and problems can and do occur. I'm sorry that you had such an experience.

    Our experience with non-authorized shops working on the product has been very poor, we have seen totally ruined amps from such attempts that we stopped supporting this as we had players asking for replacement amps (imagine that) that were ruined by horribly botched repair attempts. I'm sure you can understand if you think about it.
     
    Last edited: Jan 14, 2020
    staccatogrowl and Kartofell like this.
  10. Kartofell

    Kartofell

    May 1, 2017
    Thanks Aged Horse! I understand. I still don't like it though. I'm still going to have my tech guy work on my amp, only it will be much harder without schematics, so there's no point really.
     
    agedhorse likes this.

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