From abowyerlowe@mindscape.com Mon May 20 16:23:19 1996
    20 May 96 19:23:15 +0500
    20 May 96 08:15:03 +0500
From: abowyerlowe@mindscape.com
Date: Mon, 20 May 96 12:49:28 PDT
Subject: DR-55 Bass Drum Decay Mod...

Well, this weekend I met up with a friend of mine who also has a BOSS DR-55 Dr. 
Rhythm (groovy, groovy, groovy).

So I say to him, 'Hey, have you modified the bass drum decay?', and he hadn't so
we flipped the top off and had a look inside...

On my DR-55, in the bottom left (near the tone pot) there was a little trim-pot 
which varied the kick decay, but on my friends there was only a resistor. Later 
study of the service manual shows that only early serial number DR-55s have the 
trim pot, so if you've a later rev. DR-55 here's the extremely simple way to 
modify the bass drum decay..

The resistor is in the lower left of the circuit board (looking from above), 
just below the tone control. 'BD' is stencilled on the PCB next to it, and the 
resistor is over a little stencilled trim-pot picture. The following ASCII 
diagram should help you locate the right resistor.

           /-\
           l l   Tone Pot.
           \-/ 
       o
          o
       o  ^   
       ^==/  <<-- Resistor to be replaced.


Simply snip out the resistor, and replace with a horizontal trim-pot of several 
K ohm. The trim pot goes between the three holes in the silly ASCII diagram 
above, with the wiper terminal attached the middle/rightmost hole. I used a 2.2K
that I had floating around (what? your parts don't levitate like mine? freaky), 
and that gave a reasonable control range...

Of course, I hold no responsibility for anything bad happening from this...

On another point... I'm going to be in London from thursday this week. Any UK 
AHers want to meet up and hang out?

Regards,
Anthony.
--
Anthony Bowyer-Lowe. Audio Programmer @ Mindscape (UK).