Markbass combo amp repair

[BassmanPaul]

On 14/10/2021 at 05:10, fretmeister said:

 

While I'm very pleased that the EU is pushing the "Right to Repair" idea for some products it's not as simple as for others. Washing machines - lovely

Living in the Toronto area I have to point out that washing machines worked fine for Geddy!!!! LOL

Edited October 18, 2021 by BassmanPaul

[Due23]

I have an MB 121H combo, bought second-hand about 5 years ago. After a couple of years it changed sound and seemed  to distort sometimes. Took it to Real Electronics who changed the pre-amp board. Total cost was about £130, including VAT. The board only £30, the rest was diagnosis and repair and VAT. This all seemed ok for an amp which costs £750-800 when new.

Now it makes a whistling sound (1120 Hz) with all controls at zero and no guitar plugged in. Sounds like a power supply problem. Having removed the amp head I can see there are only two circuit boards, the pre-amp and a bigger board with everything else! If the bigger board could be supplied for, say, £100, then I could fix it myself, which would be a reasonable outcome.

I will contact Real Electronics and see what they say. I still have the original pre-amp board so can prove the pre-amp board is not making the whistling sound

[agedhorse]

Only if you are sure that's the cause of the problem. You are 50% likely to be right, but also 50% likely to be wrong.

[mybass]

What a shame MB have this repair ‘problem ongoing. When Proel U.K. were distributing them they had their own in house repair unit whereas MSL don’t (as they appear to be more a software sales than hardwire electronics outfit). I know the boss of Proel was pretty upset about all the hard work he had put in to establish MB in the U.K. Regarding ‘new age’ electronics and repairs of…I had a Yamaha PA amp/mixer that needed repairs. The repair tech had a look £30…. and advised one of two or three boards could be in need of replacement but if one was replaced and it was still a faulty amp, then he would have had to replace another until the fault was ‘repaired’…..the cost of the boards was more than buying another s/h PA amp, which is what I did and sold the unfit one off as spares.

[Sparky Mark]

18 hours ago, Due23 said:

I have an MB 121H combo, bought second-hand about 5 years ago. After a couple of years it changed sound and seemed  to distort sometimes. Took it to Real Electronics who changed the pre-amp board. Total cost was about £130, including VAT. The board only £30, the rest was diagnosis and repair and VAT. This all seemed ok for an amp which costs £750-800 when new.

Now it makes a whistling sound (1120 Hz) with all controls at zero and no guitar plugged in. Sounds like a power supply problem. Having removed the amp head I can see there are only two circuit boards, the pre-amp and a bigger board with everything else! If the bigger board could be supplied for, say, £100, then I could fix it myself, which would be a reasonable outcome.

I will contact Real Electronics and see what they say. I still have the original pre-amp board so can prove the pre-amp board is not making the whistling sound

In your situation I'd seriously consider retiring your faulty combo head and replacing it with a good condition, newer second-hand LM series head. As the CMD121H has a single 12 speaker I doubt that you are putting the full potential at 8 ohms of 300 watts through it? So you could also buy a brand new LM250 Black for approximately £200 with full warranty that can output 150 watts with likely more than enough power to drive the combo speaker to its limit. 

Edited January 13, 2022 by Sparky Mark

[BassmanPaul]

22 hours ago, agedhorse said:

Only if you are sure that's the cause of the problem. You are 50% likely to be right, but also 50% likely to be wrong.

True Dat!

[PaulHornBass]

An update on the saga.

 

Towards the end of last year, the problems with my MB combo disappeared. A bit of crackle on the volume knob, but otherwise fine. I was so pleased with the amp's Lazarus act that I recently did what I felt I should have done years ago and bought another of the combos via basschat, to live at my bandmate's house in the Midlands, where we do most of our gigs. (I live in South London with no car.) No more going direct or plugging into unfamiliar rigs. Practicing with the same rig I gig with. Great. 

 

Then, over the past week, the problems with amp number 1 came back with a vengeance. Crackling and distorted notes up and down the fretboard. So now I'm contemplating whether to: (a) send it off to be repaired; (b) buy a used LM head and attempt to install it (assuming the problem is with the head part); (c) see if I can sell the combo as 'not working' and buy another combo amp/head and cab, perhaps as @TheGreek counselled wisely earlier on this thread, from a manufacturer with better customer service such as Ashdown. 

Edited May 17, 2022 by PaulHornBass

[Sparky Mark]

2 hours ago, PaulHornBass said:

An update on the saga.

 

Towards the end of last year, the problems with my MB combo disappeared. A bit of crackle on the volume knob, but otherwise fine. I was so pleased with the amp's Lazarus act that I recently did what I felt I should have done years ago and bought another of the combos via basschat, to live at my bandmate's house in the Midlands, where we do most of our gigs. (I live in South London with no car.) No more going direct or plugging into unfamiliar rigs. Practicing with the same rig I gig with. Great. 

 

Then, over the past week, the problems with amp number 1 came back with a vengeance. Crackling and distorted notes up and down the fretboard. So now I'm contemplating whether to: (a) send it off to be repaired; (b) buy a used LM head and attempt to install it (assuming the problem is with the head part); (c) see if I can sell the combo as 'not working' and buy another combo amp/head and cab, perhaps as @TheGreek counselled wisely earlier on this thread, from a manufacturer with better customer service such as Ashdown. 

As you previously advised, you bought your old combo second-hand over 5 years ago so now it might just not be worth throwing big money at it. You can easily determine if the combo speaker is okay buy connecting it to another amp. The CMD121H is an excellent combo so I'd look out for a good condition used Little Mark head of any type (they'll all fit) to swap into the combo chassis. 

[kolossusuk]

In order to protect my ageing limbs, I decided to buy a used CMD121 H which matched perfectly the power and presence of my trusted ashdown abm evo 3 + 2x12 GB NEO cab.. Immaculate as new condition, cosmetically and a bargain price of just £350.... 

 

However, the second gig I used it on, power died completely, halfway through first set. Had to daisy chain from my MFX pedal direct into the mixer / PA - horrible... 

Transpires that it is failing at the transistors stage (circled red in attached) so, given the nature of the construction, I have booked myself in to get a repair done at Essex Amp repairs, who I have used in the past. BUT, am I wasting time, effort and money, as the amp is 9 years old and who knows what the replacement elements will cost?? I also understand there was a known board problem with this amp (Combo Head 2)  - anyone else aware of this and how was it resolved by Markbass?

Back to Ashdown for the next series of gigs!!

TIA Paul

[PaulHornBass]

On 19/06/2022 at 12:03, kolossusuk said:

In order to protect my ageing limbs, I decided to buy a used CMD121 H which matched perfectly the power and presence of my trusted ashdown abm evo 3 + 2x12 GB NEO cab.. Immaculate as new condition, cosmetically and a bargain price of just £350.... 

 

However, the second gig I used it on, power died completely, halfway through first set. Had to daisy chain from my MFX pedal direct into the mixer / PA - horrible... 

Transpires that it is failing at the transistors stage (circled red in attached) so, given the nature of the construction, I have booked myself in to get a repair done at Essex Amp repairs, who I have used in the past. BUT, am I wasting time, effort and money, as the amp is 9 years old and who knows what the replacement elements will cost?? I also understand there was a known board problem with this amp (Combo Head 2)  - anyone else aware of this and how was it resolved by Markbass?

Back to Ashdown for the next series of gigs!!

TIA Paul

Hey, sorry for the late reply - I had covid and things have been a bit sketchy. Although my problems stopped short of the amp actually cutting out, I did find a solution, albeit an expensive one. I bought a new second hand amp, the same MB combo (am I crazy?). I had it shipped to my bandmate's house in Birmingham (we do most of our gigs in the Midlands), used it at a gig last month and it was great. Amp no.1 is playing nicely at the moment for practice - if it starts getting crotchety again I turn all the knobs back and forth several times, and that gets rid of any unwanted crackling. I also have it sitting on a chair for added clarity when practicing. I don't know if that's that helpful to you really... Maybe I should have been twice shy after being bitten, but I love the MB sound - to me it is a wonderful blank canvas.

 

Did you get yours back from Essex Amps, and if so what was their verdict?

Edited June 29, 2022 by PaulHornBass

[BassmanPaul]

On 03/10/2021 at 07:29, lemmywinks said:

I wonder if taking it to someone who does board repairs for laptops etc might be a better route, probably much cheaper I would guess. 

I doubt it. Laptops and amplifiers are completely different animals and need vastly different diagnostic methology and tools.

[kolossusuk]

On 29/06/2022 at 19:14, PaulHornBass said:

Hey, sorry for the late reply - I had covid and things have been a bit sketchy. Although my problems stopped short of the amp actually cutting out, I did find a solution, albeit an expensive one. I bought a new second hand amp, the same MB combo (am I crazy?). I had it shipped to my bandmate's house in Birmingham (we do most of our gigs in the Midlands), used it at a gig last month and it was great. Amp no.1 is playing nicely at the moment for practice - if it starts getting crotchety again I turn all the knobs back and forth several times, and that gets rid of any unwanted crackling. I also have it sitting on a chair for added clarity when practicing. I don't know if that's that helpful to you really... Maybe I should have been twice shy after being bitten, but I love the MB sound - to me it is a wonderful blank canvas.

 

Did you get yours back from Essex Amps, and if so what was their verdict?

Likewise, apologies for delay in response. My buddies at Essex Amp Repair appear to be having problems making contact with distributor / parts. Transpires that I need a replacement power module......

[Phil Starr]

2 hours ago, kolossusuk said:

On 29/06/2022 at 19:14, PaulHornBass said:

Did you get yours back from Essex Amps, and if so what was their verdict?

Likewise, apologies for delay in response. My buddies at Essex Amp Repair appear to be having problems making contact with distributor / parts. Transpires that I need a replacement power module......

The problem in a nutshell. Mark Bass won't deal direct and support even the best repairers and the only place to get replacements is Real Electronics who have a monopoly.