Simple FatMan Mods     Text Only            Scott R. Gravenhorst
                                          chordman@ix.netcom.com
Fine Pitch / Fine Pitch Offset
The Fine Pitch Mod consists of simply wiring a 5K pot in series 
with the original 100K pitch and/or pitch offset control to 
create a coarse/fine system.  The fine control has 5% of the 
effect that the coarse control has on the associated VCO pitch.  
When using the new system, always adjust the fine control to mid-
range first.  Then use the coarse control to get close, trimming 
out with the fine.  This system allows much better control over 
the flange effect between the two VCO signals.  I have an extra 
panel mounted above and below my FatMan.  I positioned the fine 
controls directly above the coarse (original) ones on the added 
upper panel.  An alternative approach is to replace the 100K 3/4 
turn pot with a 100K 10 or 20 turn pot.  This is a more expensive 
method, however.
  
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Level controls for VCO1 and VCO2
Requires 2 additional 10K pots.

1) Remove R46 and R55 from the FatMan PCB.

2) Unsolder wires H and F from the PCB and solder them to the 
wiper contacts of each respective level pot.  (NOTE: Leave wires 
F and H soldered to the 1/2 MIX pot)

3) Connect a wire from each level pot low side to ground, found 
easily on FatMan panel.

4) Connect a wire from the PCB 'H' hole to the hot side of the VCO 
1 level control 10K pot.

5) Connect a wire from the PCB 'F' hole to the hot side of the VCO 
2 level control 10K pot.

              This is what you end up with:

                                                +------------
                                                |
                                                V
                      +---------------------\/\/\/\/\---+
        'hot'         |                       1/2 MIX   |
         end          V     10K                         |
To PCB   --------\/\/\/\/\------+                       |
wire H hole        VCO 1 level  |                       |
                                |                       |
                             GROUND                     |
                                                        |
                                                        |
                                                        |
                      +---------------------------------+
        'hot'         |
         end          V     10K
To PCB   --------\/\/\/\/\------+
wire F hole    VCO 2 level      |
                                |
                             GROUND


If you turn the level pots all the way up, the 1/2 MIX pot works 
as before.  If you want to silence one or both VCOs, use the 
level pots.
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