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Help me fix Boss BF-2 and DM-3

11/12/1999 7:14 PM
frank
Help me fix Boss BF-2 and DM-3
Hi, I've decided to try and fix a couple of Boss pedals I've got lying around, and am seeking some help.  
 
BF-2: The resonance knob causes the unit to feedback rather severely when cranked, even with no input signal. Is this a result of a trimpot inside being incorrectly set? Someone here sent me a schematic a while back which I lost when changing computers, sorry. I believe there are three or four trimpots on the PCB - what does each do? Are they suitable for tweakign the sound, or are they best left alone?  
 
DM-3: There is an electronic-sounding overtone present with each delayed note, but not the original. When I asked about this a while back, someone suggested it might be the clock signal bleeding through, and this might be due to a bad cap not filtering it out. Is this possible? Could it be fixed by identifying the bad cap and replacing it, or is there more going on here? Does anyone have a schematic? I can handle switching components, but any serious troubleshooting of complex circuits like this are out of my league.  
 
I'd like to get these units working properly, cause I think I may want to sell them and am not comfortable unloading a pedal that I know not to be in 100% working order.  
 
And on a related note, both these pedals are of the ACA-adapter type. I haven't been using one. Can they be damaged by using the lower-voltage PSA adapter, or any other regulated 9V power supply? Or would they just not sound their absolute best?  
 
Thanks greatly for any help here.  
 
Frank

 
Replies:
Mark Hammer BF-2: Your suspicions about the tr... -- 11/14/1999 8:38 PM