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Post new topic Where Is The Fuse MB 200
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Author Topic:  Where Is The Fuse MB 200
Jon Jaffe


From:
Austin, Texas
Post  Posted 24 Nov 2020 12:49 pm    
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While cleaning out a closet in the garage, I came across a bricked MB 200. I felt lucky after going to Play It Again Sports and coming home with a check for $400 for some used golf clubs. So why not tackle this MB 200 and make it work again. The way it was not operating made me think that a fuse was burned out. I got the cover off to discover that there was a note about fuse replacement but no obvious fuse that I could discern. I have included a picture for your inspection.

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Jerry Overstreet


From:
Louisville Ky
Post  Posted 24 Nov 2020 1:26 pm    
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Disclaimer: I know nothing about these and very little about electronics in general.

What is that underneath the metal cap there in the bottom left hand corner?

Anyway, I found the operating manual here: https://www.manualslib.com/manual/593283/Gallien-Krueger-Mb200.html#manual but it does not show a fuse and there is no schematic. There is a desciption of the protections circuit on pg. 9 and a prompt to contact GK directly for help.

I know some circuits in the auomotive industry used what is called fusible link which would be a safety junction in the wiring that melts to an open circuit in case of overheat or short circuit, but I dunno if any of that applies to pro audio gear.
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Jon Jaffe


From:
Austin, Texas
Post  Posted 24 Nov 2020 3:08 pm    
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Thanks, the wire you refer to is a ground. I looked at the manual it did not help. I went to the Galien-Kruger website that referred me to a repair shop in Austin about seven minutes drive from my house. I trust them to tell me whether or not it's worth it to repair.
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Lee Baucum


From:
McAllen, Texas (Extreme South) The Final Frontier
Post  Posted 24 Nov 2020 3:58 pm    
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Jack Stoner may be of some help.

He was a long time amp tech and (I believe) used to have one of these amps.
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Kevin Mincke


From:
Farmington, MN (Twin Cities-South Metro) USA
Post  Posted 24 Nov 2020 6:51 pm    
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The red circle with arrow points to fuseable link.
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Jerry Overstreet


From:
Louisville Ky
Post  Posted 24 Nov 2020 9:16 pm    
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that's what I first stated in my post, but then deleted it because I decided the grn/y wire might be bolted to the chassis, so that wouldn't work. Can't see what's on the other side of the circuit board so....
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Jon Jaffe


From:
Austin, Texas
Post  Posted 25 Nov 2020 3:40 pm    
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It is a ground wire bolted to the chassis.
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Don Poland


From:
Hanover, PA.
Post  Posted 25 Nov 2020 4:17 pm    
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The fuse or fusible link wouldn't be on the ground. Hard to tell from the picture posted where it may be.
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Lee Warren


From:
Nashville, Tennessee, USA
Post  Posted 25 Nov 2020 5:19 pm    
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Schematic.
Sorry I couldn’t patch the two images together on my iPad.
Hope this helps.



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Roger Dillingham


From:
Kentucky, USA
Post  Posted 25 Nov 2020 5:39 pm     Mb200
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I think that Kevin and Don are both right. The area that Kevin has circled should be where there is a fusible link wire. As Don stated, it would not be on the ground side but that area should definitely be where the culprit is located. You would, of course have to refer to some schematic in order to establish the value of the fuse link unless you can identify by looking at the markings on the wire itself. If you can tell from the images that Lee provided that should enable you to get the appropriate rating. It does appear to be quite heavy gauge, but that would be expected since it's always right after the AC power input cable comes into the unit. Good Luck! Roger
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George Biner


From:
Los Angeles
Post  Posted 25 Nov 2020 5:46 pm    
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I can't find a schematic on google.

The big board in the middle is the digital amp, from ICE, Gallien Krueger just buys it and sticks it in the box.

Here is the owner's manual
https://www.manualslib.com/manual/358382/Gallien-Krueger-Mb200.html?page=1#manual

There is no mention of a fuse. I guess it has a smart protection circuit instead.
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Electrical Engineer / amp tech in West Los Angeles
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Don Poland


From:
Hanover, PA.
Post  Posted 26 Nov 2020 11:07 am    
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Found these, still looking for others.

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David Ball


From:
North Carolina High Country
Post  Posted 26 Nov 2020 11:48 am    
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I've seen posts on some of the bass pages regarding the MB200 fuses, and I've seen them referred to as the "inline fuse resistors." Those might be all there are.

Dave
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Jerry Overstreet


From:
Louisville Ky
Post  Posted 26 Nov 2020 12:22 pm    
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Hard to tell without hands on, but I'm still suspect of the left bottom corner under the metal cap. That looks like a glass tube that is used in some audio gear, but again I state, certainly no expert here.
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Randy Owens


From:
West Central Indiana, USA
Post  Posted 26 Nov 2020 2:14 pm    
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Could it be the component just above F101 as marked on the board? There are actually two markings on the board that are identical to the picture shown on the paper tag. Look about halfway down the right side by those two red brick-looking components.
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2003 Mullen Royal Precision, Walker Stereo Steel, Ampeg G-15, Telonics FP-100
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Larry Dering

 

From:
Missouri, USA
Post  Posted 26 Nov 2020 6:38 pm    
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Got this from the Bass forum. They are fuse resistors. The pencil points to them.
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Greg Cutshaw


From:
Corry, PA, USA
Post  Posted 26 Nov 2020 9:11 pm    
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Those fuse resistors look like color code Brown, Black. Black or 10 x 1 = 10 ohms and can be identified here (last page):

http://cosonic.in/Catalogs/Winsonic_Fusible_Resistors_Catalog.pdf

Most of the digital amps I've repaired had blown switching power supplies including the main coil and regulator. I use a ring detector to check the coils for shorted turns. My success rate on fixing these is under 50%. After stuffing all the bad parts into them that I can ID they have some chance of working but many have charcoaled the board wiring.
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Larry Dering

 

From:
Missouri, USA
Post  Posted 27 Nov 2020 8:41 am    
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Greg I agree and find it not worth the time and effort. These are virtually a throwaway amp like so many more of today's electronics. I have a TC electronics G major on my workbench and it was a nightmare just finding a replacement rotary switch and even more a problem with the crappy circuit boards tiny solder traces. Not sure I can save it afterwards.
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Jerry Overstreet


From:
Louisville Ky
Post  Posted 27 Nov 2020 10:11 am    
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Yeah, my experience and understanding of Class D devices are they are almost never repairable.

It's just that that label indicates that there might be an actual replaceable fuse that a user could access.

Even though most devices have a warning label on the case that there are no user replaceable parts inside, there sometimes are.

Of course even a blown fuse might be indicative of a greater problem that caused the fuse to go.
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Jon Jaffe


From:
Austin, Texas
Post  Posted 27 Nov 2020 10:11 am    
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As I said in my initial posting, I was going to throw the MB 200 in the trash. Since I was on a roll I decided to take it apart and look. I did not see any serviceable items so I closed it back up and posted on the Forum. After the first reply I took it to a GK service center. It was in a locally owned guitar shop that is very musician centric. I plan to throw it away in a week, after stripping it up some parts that I will never use. Thanks for your interest.
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