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Repair help - MM Sub4 bass output issue

Posted: Tue May 22, 2018 10:07 am
by Andrew McSpadden
I got a MM Sub4 , standard single HB and active electronics 4 string, that has a weird output issue. It only has out put when the string is struck hard and then only briefly and distorted. Battery is good and the pickup reads 6.35K. Solder joints and connections look good. Any suggestions?

Re: Repair help - MM Sub4 bass output issue

Posted: Tue May 22, 2018 12:33 pm
by David King
Do you get the same result when the battery is removed? #1 most common issue is the battery leads breaking off or the battery clip not making a good connection. Many active basses will behave exactly this way without the battery.

Re: Repair help - MM Sub4 bass output issue

Posted: Tue May 22, 2018 12:58 pm
by Andrew McSpadden
I think I found it. a diode or transistor on the PCB was fried and fell off when I touched it. Contacted MM to see if I can get a replacement.

Thanks for looking and responding!

Re: Repair help - MM Sub4 bass output issue

Posted: Tue May 22, 2018 10:09 pm
by David King
That's a wild one, I wouldn't have thought a 9V battery could put out enough of a sustained current to cause that kind of damage. The other question is was it just one bad transistor/diode or was there another failed component that caused the one to fry.