There actually isn't a CPU- the TC5501 is a RAM chip (interesting design!). I think this would be a very easy problem to solve with an oscilloscope, but things get a little more "interesting" if you don't have one. Do you hear the "flam" sound on the hi-hat sound? Do the "16" and "8" modes work properly (8 should be half-speed)? Do they both have the "flam" sound? Do you have a way of observing what comes out of J2? C42 should determine the tempo, so it's probably fine. ________________________________ To: vintagesynthrepair@yahoogroups.com From: freckles@... Date: Sun, 12 Oct 2008 17:23:59 +0100 Subject: Re: [vintagesynthrepair] Boss DR-55 sounding problem - FINALLY! Hi Scott thanks for your info, and sorry for the HUGE delay in getting back to this. Its not a start-button problem. regardless of what is programmed in the memory, when the cpu [tc5501] sends out the drum trigger signals, its like each trigger is doubled. its not a semi-quaver apart but maybe 10ms or something, which makes me wonder if the sounds are restarting on the falling edge of the trigger pulse as well? but maybe its more basic than that.. my knowlege of electronics is very limited - i don't even understand what's happening in the clock circuit, maybe the problem is there as it connects directly to one of the cpu pins next to the trigger outputs.. ? what would happen if C42 was faulty? What does NP 1/50 mean [next to C42]. I tried replacing the 4011UB but no change. Any help very much appreciated Thanks Chris Scott Nordlund wrote: > I don't have a DR-55 but I downloaded the service manual for my own > amusement (I'm cool like that). I would guess that the note button is > double-triggering, and the sequencer then correctly plays back the > wrongly-entered sequences (where you can turn the tempo down and hear > two successive steps rather than a double-triggered flam), yes? If > I'm understanding this correctly, the rest button shouldn't > double-trigger, and you should replace C45. > > ---------------------------------------------------------- > To: vintagesynthrepair@yahoogroups.com > From: freckles@freeola.com > Date: Thu, 10 Apr 2008 18:10:14 +0000 > Subject: [vintagesynthrepair] Boss DR-55 sounding problem > > Hi just wondering if anyone has some advice/tips for me. > > I have what appears to be a fully working DR-55 except the drum sounds > are double-triggering. most noticeable is the kick which obviously > flams, making it sound very farty. > > I don't have a scope but i've recorded it to my laptop and can see the > double peak. > > Anyone have any idea what it could be? I can mail relevant service > manual pages if that helps. > > Thanks > > > > ---------------------------------------------------------- > More immediate than e-mail? Get instant access with Windows Live > Messenger. > > _________________________________________________________________ See how Windows Mobile brings your life together—at home, work, or on the go. http://clk.atdmt.com/MRT/go/msnnkwxp1020093182mrt/direct/01/
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RE: [vintagesynthrepair] Boss DR-55 sounding problem - FINALLY!
2008-10-12 by Scott Nordlund