MOTM-310 fine tune range modification – New 02/10/02

Just as with my MOTM-300, I found the fine tune range on my MOTM-310 too wide for
my personal preference. On the unmodified MOTM-300, it is about 11 semitones. I
changed mine to 4 semitones. See my MOTM-300 modification document for details.

I found the unmodified MOTM-310 fine tune to have a range of 8 semitones. I wanted to change that to approximately match my modified MOTM-300 range of 4 semitones.

The change is again simple (although applied differently than the MOTM-300).
You have two easy choices:

  1. Change R17 from a 4.7 Meg-ohm to 10 Meg-ohm resistor. However, a 1%
    tolerance resistor of 10 Meg-ohm can be difficult to find.
  2. Add a 4.7 Meg-ohm resistor in series with R17. This involves cutting one trace
    that connects two via holes and adding the 4.7 Meg ohm resistor connecting to
    these two via holes.

The resistor addition is very near the tempco resistor. Here are links to the photos:
(top of PCB) (bottom of PCB). I think they detail everything, but drop me a note if
you have questions.

This modification is easily reversible. You can restore the cut trace by soldering
a resistor lead between the two via holes where we are installing the 4.7 Meg-ohm
resistor.

Disclaimer: I am not an engineer. I am not suggesting that you change your 310 or
take any of my advice. However, I am reporting MY results on modifications to my 310 modules. Remember, your results may vary.
Larry Hendry

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