Markbass LMII: an inside view :)

[deBont Amps]

I reconfigured my Markbass LMII today, so the effectsloop works in serial instead of parallel (thanks Kjung for the jumper location PDF). While in there, I made some pictures to share on TB, for the curious ones
I noticed there are a lot of unused connectors and solderpoints with interesting labels like 'pre-post', 'Aux', 'Mix(+), etc. Makes me wonder if there are some coll modifications possible . I wonder what's in the rest of the service manual...

Link Removed

 

[Psycho Bass Guy]

I noticed there are a lot of unused connectors and solderpoints with interesting labels like 'pre-post', 'Aux', 'Mix(+), etc.

Those are most likely test/diagnostic points. That amp is heavily populated with surface mount components which means it is basically unrepairable at the component level, so most repairs are like computers, board swaps. The test points determine which boards get pulled.

 

[murphy]

WOW!!!
Cool photos.
Thanks for showing us

 

[Vin_MM_Sabre_79]

Yeah cool.
I'm trying to spot the jumpers for voltage conversion- can't make em out.

 

[Loel]

Cool pics

Is there a pic of the jumper
to switch from post to pre DI,
i still haven't switched my DI setting..

 

[USAJO]

wouldn't this void any warranty?

 

[koobie]

Those are most likely test/diagnostic points. That amp is heavily populated with surface mount components which means it is basically unrepairable at the component level, so most repairs are like computers, board swaps. The test points determine which boards get pulled.

That brings up an interesting point. If & when this new generation of micro-amps start to require repairs (outside of a manufacturer's warranty), what might the expected repair costs be, relative to the purchase price? And I'm not just singling out Markbass here, I'm thinking of all the similar size/wattage heads on the market now. Just like when you buy a car, the price you pay to drive it off the lot doesn't really reflect the true cost of ownership.

 

[JimmyM]

I don't see any reason why the cost of repair would be any different whether you swap out boards or replace giant SVT transformers or whatever. I got hit with a $300 bill to replace the caps in my 73 Super Reverb, replace a broken pot and knob, and convert it to blackface specs, so if it costs $300 to swap out a board, what's the difference? But I would think the likelihood of getting a repair bill like that for a $600 amp would be less. One place it definitely saves money is in bench charges. Can't take very long to test an amp at predetermined points, pop out a bad board and pop in a good new one.

 

[deBont Amps]

Yeah cool.
I'm trying to spot the jumpers for voltage conversion- can't make em out.

Cool pics

Is there a pic of the jumper
to switch from post to pre DI,
i still haven't switched my DI setting..

Resolution is pretty low, so things are hard to make out. If anyone would like the full resolution pics, just PM me, so I can mail them to you.

 

[jnewmark]

I don't see any reason why the cost of repair would be any different whether you swap out boards or replace giant SVT transformers or whatever. I got hit with a $300 bill to replace the caps in my 73 Super Reverb, replace a broken pot and knob, and convert it to blackface specs, so if it costs $300 to swap out a board, what's the difference? But I would think the likelihood of getting a repair bill like that for a $600 amp would be less. One place it definitely saves money is in bench charges. Can't take very long to test an amp at predetermined points, pop out a bad board and pop in a good new one.

And where and who would be able to fix it after the warranty runs out? Will MarkBass give local tech guys their authorization to work on them?

 

[deBont Amps]

I guess that every authorized Markbass dealer with some sort of technical department can make a basic diagnosis using the service manual and order replacement boards directly from Markbass. So repairs in the future shouldn't be a problem.
It works this way with other electrical equipment and I don't think this will be any different with Markbass.

 

[Psycho Bass Guy]

That brings up an interesting point. If & when this new generation of micro-amps start to require repairs (outside of a manufacturer's warranty), what might the expected repair costs be, relative to the purchase price?

Chances are that one an amp goes out ot production, it will be like most other modern electronics, disposable. If the amp's boards are no longer being produced and defective components cannot be replaced, you'll have yourself a nice lightweight boat anchor.

 

[Kennethfaria]

or a heavy paper weight, OR even a new dumbbell!

 

[fdeck]

Those are most likely test/diagnostic points. That amp is heavily populated with surface mount components which means it is basically unrepairable at the component level, so most repairs are like computers, board swaps. The test points determine which boards get pulled.

I've done surface mount repairs at the component level, and have seen it routinely done by others. Some parts are easier to swap out than others. But I see nothing difficult in those MarkBass pics.

What I see as potentially difficult with switching and Class-D amps is finding direct replacements for some of the semiconductors as they are discontinued by manufacturers. This, and simply the lack of widespread repair expertise, are what will likely make repairs difficult.

I won't deny the fact that this is a potential drawback compared to e.g., tube gear that is relatively easy to repair.

 

[koobie]

I don't see any reason why the cost of repair would be any different whether you swap out boards or replace giant SVT transformers or whatever. I got hit with a $300 bill to replace the caps in my 73 Super Reverb, replace a broken pot and knob, and convert it to blackface specs, so if it costs $300 to swap out a board, what's the difference? But I would think the likelihood of getting a repair bill like that for a $600 amp would be less. One place it definitely saves money is in bench charges. Can't take very long to test an amp at predetermined points, pop out a bad board and pop in a good new one.

A $300 repair bill to fix a twenty-five year old amp? That's not too bad if you've gotten a lot of service from it. Many of the BF & SF Supers I've seen have hundreds, if not thousands of gigs under their belt. And a portion of your repair cost included modifying the SF circuit to BF specs, that wasn't strictly mandatory.

I used to sell mid-level to crazy high-level stereo/audiophile gear. I hated to see the looks on customer's faces when our tech would tell a customer that his out of warranty $500 CD player would cost $250 to repair. The techs I knew weren't adjusting bad laser assemblies (I don't think they could have if they wanted to), they were replacing assemblies outright. Part of our disposable society, a damn shame.

 

[eutgard]

Inside of LMII

There is 120/240 selection jumper.

And it will void your warranty if you do it yourself.

DIY voltage change success from 120 to 240 so far

F1

Mini CMD 121P

LMII


In South Korea, there is huge interest in Markbass product.

After importing 120V model from Japan or USA, users do volatge change by themselves.

And I love my Italian red limited edition F1

 

[fdeck]

Inside of LMII

There is 120/240 selection jumper.

And it will void your warranty if you do it yourself.

DIY voltage change success from 120 to 240 so far

F1

Mini CMD 121P

LMII


In South Korea, there is huge interest in Markbass product.

After importing 120V model from Japan or USA, users do volatge change by themselves.

And I love my Italian red limited edition F1

Some amps also require a different fuse when changing the line voltage setting. And isn't Japan on 100 V?

 

[eutgard]

110V, actually.

220V in South Korea and after jumper relocation, everything's fine so far.

 

[JimmyM]

A $300 repair bill to fix a twenty-five year old amp? That's not too bad if you've gotten a lot of service from it. Many of the BF & SF Supers I've seen have hundreds, if not thousands of gigs under their belt. And a portion of your repair cost included modifying the SF circuit to BF specs, that wasn't strictly mandatory.

I used to sell mid-level to crazy high-level stereo/audiophile gear. I hated to see the looks on customer's faces when our tech would tell a customer that his out of warranty $500 CD player would cost $250 to repair. The techs I knew weren't adjusting bad laser assemblies (I don't think they could have if they wanted to), they were replacing assemblies outright. Part of our disposable society, a damn shame.

It's actually a THIRTY-five year old amp now...time flies, eh?

I'm torn between the wasfeful aspect of disposable electronics and the practical aspect. I look at PC boards these days, and to me it only makes sense to set them up to where you pull a board and replace it. It might mean replacing $100 worth of stuff to replace a $2 component, but when you figure in bench charges to replace that $2 component in a complex web of components, seems to me that with disposable electronics the bench charges will get greatly reduced, so at this point and time, I view it as a wash.

 

[Nenor]

Inside of LMII

There is 120/240 selection jumper.

And it will void your warranty if you do it yourself.

DIY voltage change success from 120 to 240 so far

F1

Mini CMD 121P

LMII


In South Korea, there is huge interest in Markbass product.

After importing 120V model from Japan or USA, users do volatge change by themselves.

And I love my Italian red limited edition F1

Hi there eutgard,
From what I know converting voltage in MB amps requires actual soldering.
In your picture the jumper hangs on only one leg. Is this OK? Is that all needed to convert from 110V to 220V?

Actually, is this an LMII in your picture? I'm looking at the open LMII at the top of the page and can't find an exact match.