GK MB150E Problem: Speaker cuts out

[improv]

What ever happened with your amp? I have the same problem with my MB150e/MBE-112. I have cleaned all the inputs, have even done the send/receive bypass and it has cut out on me. It won't cut out when I practice with it for hours, but after a few minutes sometimes it will cut out when played in a rehearsal or on a job.

Does anyone have a schematic that I could have for this thing?

Thanks,
Mike

 

[freshbass]

Mine was cutting sound to about 80% once in awhile so I unplugged it and cleaned all the 1/4 input jacks, push switches, and behind the knobs w/ QD electronic cleaner spray and let it sit overnight. Problem went away. Next step would have been to open it up (not easy) and use deoxit.

 

[EarlyMiles]

10164094[/URL], member: 40185"]I have a MB150E. My advice: When it cuts out, try all of the jacks. See if you get sound when plugging into the stereo aux input, for instance, or the effects return. You could have some dodgy "switching" jacks, particularly in the effects loop. Try a patch cord in the effects loop. Plug in an external speaker. In short, try all of the possibilities, to isolate the problem to a specific portion of the amp.

I had this problem on-and-off with my MB150S, but last night at my gig - the speaker turned off pretty much permanently - though the signal going to the board through the XLR Direct out was fine (luckily). FDeck, Dominic D, and freshbass suggested to plug in a patch cord in the effects loop - seems to work. My understanding is as follows: When you put a 1/4’’ jack in either send or receive jacks of an effects loop, it cuts the speaker. A patch cord closes the loop and reinstates the signal. So I assumed one of the jacks caused the problem and intermittently shut the speaker off. I could not know which one - but that does not matter. I went about cleaning both jacks and the speaker no longer cuts out. Happy! Many thanks to FDeck, Dominic D, and freshbass. Now I need another gig to test this out.