HELP GK MB 210 II fan noise (Gallien Krueger)

WorbyBass

WorbyBass

Apr 24, 2024
27
46
506
Regina SK Canada
#1
Hey guys, got an issue here. Wonder if anyone’s faced something like this, if it’s a fairly simple fix. I’m guessing I need a new fan??

Just bought this bass amp package used. I could hear the fan whining a bit, but it didn’t seem like a big deal. Now I’ve pushed it harder and it’s annoying!

Seemed like a good deal. It’s a GK MB210 II Which has 2 x 10 + horn which is 350 watt Class D as is (500 watts @ 4 ohms). Came with the GK 115 MBP which is a 200 watt powered 1x15 + horn. Nice and full sound as a unit, with clarity. I plugged in my Dingwall Combustion 6 to test and it sounds decent. But at low volumes, I hear that whining sound that keeps changing speeds… Buyers remorse!

Thought I could post a video clip, but maybe it’s because I haven’t posted enough?? Okay, I’ll edit this into a YouTube video and provide a link.
 
#3
Contact — Gallien-Krueger
Gallien-Krueger
2234 Industrial Drive,
Stockton, CA95206

Tel: 209-234-7300
Fax: 209-234-8420


Call and ask for Parts. It sounds like someone used compressed air to "blow the dust" out of the fan and damaged it. They are a variable speed fan 24volt IIRC controlled by temperature.
Any time someone tries to use compressed air (not recommended) you must use something like a wooden orange stick to stop and keep the fan blade from being driven over-speed and damaging it.
 
  • Like
Reactions: WorbyBass and MCF
#4
Could be a defective fan or the fan controller. You. Red to use the factor specific fan because the controller curve is designed to the specific fan.

Contact GK.
 
  • Like
Reactions: WorbyBass and B-string
#6
B-string said:
I should have said Fan variable speed controlled by temperature. Under mild heating they turn slow and ramp up as temperature increases. The mention of the fan voltage is only one factor, size, current draw and CFM are others. Call the GK number.
Click to expand...
Also the CFM versus voltage and/or current curve depending on the controller.
 
  • Like
Reactions: WorbyBass
#8
WorbyBass said:
Thanks guys, I appreciate the help and the contact information. I’ve reached out to GK and sent them a video for reference. I’m in Canada, so I hope I can get parts here. We’ll see where this goes. I’ll update once I know more.
Click to expand...

Use the link and you can find GK dealers map in Canada that could help if Stockton has any trouble shipping to Canada. Myself personally have had intermittent luck with the email system, but that was at a time they were closing the GK owned and operated factories in China and bringing supplies into the states (maybe Bob G heard something in the wind). It has been some time since I've had a need to contact them, they are great people with long records of maintaining employees.
 
#9
My GK MB210's fan suddenly got very loud, when I never really noticed it before, and then after a few seconds the power amp died and would not power back up. It has done that twice. In both cases i was just playing practice volume at home.

It is in Stockton for the second repair right now. My GUESS is that fan is not defective, but that a faulty component or connection is overheating beyond what the fan can control. Just a guess, like i said.
 
#10
B-string said:
Use the link and you can find GK dealers map in Canada that could help if Stockton has any trouble shipping to Canada. Myself personally have had intermittent luck with the email system, but that was at a time they were closing the GK owned and operated factories in China and bringing supplies into the states (maybe Bob G heard something in the wind). It has been some time since I've had a need to contact them, they are great people with long records of maintaining employees.
Click to expand...

Good call! There is a dealer in my city, they just don't have any in stock so I didn't know they were an official dealer.

I sent GK an email last night. I realized later that they'll probably want to know serial number and such. I'm hoping to get home early enough to phone today. Anyhow, I'll see how this all goes.
 
  • Like
Reactions: B-string and p12bassnut
#11
WorbyBass said:
Good call! There is a dealer in my city, they just don't have any in stock so I didn't know they were an official dealer.

I sent GK an email last night. I realized later that they'll probably want to know serial number and such. I'm hoping to get home early enough to phone today. Anyhow, I'll see how this all goes.
Click to expand...

Yes they will want the serial number to know if a revision was or needs to be done. Likely not with fan or controller but you never know and you can find out when it was born into this world. Under or out of warranty only matters to who will pay for the parts of course. Hoping for a speedy conclusion.
 
#12
UPDATE: I emailed GK again (had sent the first one to the wrong department). I sent the email LATE last night, got a reply by 11 AM today!! Glad they provide prompt support. I'm already feeling better about not being as shrewd as I should have been.

GK figures it's the fan, gave me some tips to try and diagnose it. He said that the 115MBP has the exact same fan, said I could try to swap it out to test but that it's a pain to do. I have soldering and fixed a lot so I may carefully give that a go. But first things first, I'll pull apart the MBP210-II and get a better look at that fan. He said there's pretty tight tolerance between the bearing and the housing, so dust (or bent blades) could certainly cause trouble. There's no use taking apart a perfectly good amp and risk damaging it if the MBP210-II is obviously broken. They'll also get me a quote on the part.

Of note: That 115MBP fan never makes a PEEP, even when I push it hard. So then the basic design is good.
 
  • Like
Reactions: B-string and agedhorse
#13
Well… after swapping out the fans, they both change speed all the time. I made another short video and sent it to GK of both fans acting up. At this point, they’re pretty sure it’s the temp/fan circuit as was mentioned above. That was on Friday.

Yesterday I had a bit of a scare. I was testing it some more, played for half an hour, and the fan never came on once! Things started feeling a bit warm so I stopped playing. I left it on for another half hour thinking the fan would eventually come on. It did not! I grabbed a temperature gauge and was reading temp as high as 125F (only in a very precise location). So now I’m worried playing this thing at all until I can get the new part. Hopefully I get the information about cost & wait time shortly.

In the meantime, I’m really growing to like this combo. The MB210-II by itself lacks low end. Paired with the 115MBP It’s pretty monstrous! No trouble at all handling low A!! What I love is I can have really thick low end and still have the clarity for my mid and high-end. I use my Dingwall combustion 6 for these types of tests. It even handles complex chords with clarity. Very interesting!
 
#14
Sounds like the control circuit. These were the original factory fans right? If not, the set point and Speer versus temperature curve can result in improper fan speed (or no fan speed) as the temperature increases.
 
#16
If the replacement fans were the same as the original (either brand and model or GK provided authorized substitute), then the problem has to be with the control circuit.
 
#17
Solution on route.
GK had me try a cool trick, test the fans with a 9v battery! Both fans work great with the battery, smooth and consistent. So then it is temp sensor related.

The options were $10 USD for 2 parts (temp sensor and something else just in case) and resolder the circuit board OR $59 USD for a whole new preamp. I went for the whole preamp!! Some pots are getting scratchy, and it's 10 years old. This solves everything. $25 USD shipping regardless. Plus I'll keep the old preamp for parts just in case. I'll update once I get the beast running again.

GK has been really good to deal with. I am surprised. I was up front from the start that I bought it used and they have been great. Certainly makes me want to deal with them more in the future. Fabulous support!!
 
  • Like
Reactions: abarson and B-string
#19
UPDATE: This is finally solved! I have to say that GK is an incredible company!! They knew I bought a used 10-year-old amp, but still gave me a lot of service. I make a lot of purchase decisions based on customer service. This is right up there with the best service I’ve seen. I have full confidence in dealing with this company in the future.

I was quite befuddled when I received my new preamp and multiple parts did not make sense😅. I actually thought they sent me some wrong parts, was quite surprised how much I got for the money. Of course it had gone through multiple revisions over the years. I needed help! GK got one of their techs, who took apart an existing amp and gave me detailed photos and instructions. So much of the layout of the circuitboard had changed that it wasn’t easy to see how it went together.

Here’s a picture of the assembled preamp connected to the power ramp. Above that is my old preamp and all the other parts that came out.

_image.png


$59 USD to replace all that is not bad at all. The one annoying part was UPS. Many Americans don’t realize that when you ship UPS, they charge about $35 Canadian just to clear customs. I ended up paying about $105 USD total after shipping and brokerage. But all in all this isn’t bad! Especially when I didn’t have to pay a repair person to do any of the work. Mind you, I’ve repaired a lot myself, don’t mind getting my hands dirty, and figuring things out. With how much I spent on the 2 amps I’m still really happy.

When I had it all assembled, I had another scare! Strange chirpings were coming out of the amp, like dial Internet. I was really dismayed for a couple of days. Then I got to thinking that my plug-in might just have a bad ground. I moved the amp to a different plug-in and everything was nice and quiet.

Except… Some crazy rattle when I was playing at moderate volume. I thought maybe a speaker cone was blown. Well, after some more problem-solving, it was another non-issue. The grill for the horn had come loose and got wedged between the speaker cover and the cabinet😅. I glued that in place and decided I would tighten everything while I was in there. This is one serious amp! Very well built. Solid materials on the inside. Baffles and channels to tune and direct sound.

What I also noticed is their care and the attention and areas that customers would never see. Even something as simple as the GK logo. First off, it’s heavy duty! To make sure it doesn’t rattle, there are 3 bolts with 3 nuts and 3 lock washers. Who does that? Most of the time it’s a crappy logo just glued on that falls off easily. You can yank on this and it doesn’t move!!
_image.png


So… Sound test. Holy smokes can this thing go loud!! And it retains definition!! I’ve got a 6 string Dingwall Combustion bass. I can play complex higher triad chords with some low drop A droning And it all comes through. Now, a good part of that is the bass. But we all know that a crappy amp can ruin a great bass. I’m so happy that I could play loud and clear.., and thumping!!! 😃

Thanks again to the people here who directed me to call GK. It took a while, but this is ended very well.
 
Last edited:
  • Like
Reactions: pcake, B-string and agedhorse
#20
@rag I don't know if it was part of your vision way back in the mid/late 1960's to build a legacy like your company GK. Beyond your engineering skill you enacted a very successful business model that is unparalleled. There are not many constants in the electronics industry period that someone can point to and say: Just contact them, they will support their products. While it means little to the world, the list of people I admire in this industry is pretty short and include @agedhorse who will go the extra to support the products he developed under varied brand names. These products it seems are almost like the children of your careers and the continued support and dedication does not go un-noticed.
 
  • Like
Reactions: agedhorse and OldogNewTrick
You must log in or register to reply here.
Top Bottom
Back