OB-1 New Programmer Installation Instructions	R Grieb 4/2/2016

To install the new programmer board, perform these steps:

1) Check the tuning of both oscillators, and confirm that the 
coarse frequency steps are perfect semi-tones.   If the calibration 
is off with the original programmer, it will be off with the new one
as well.   The pots for calibrating the oscillators are not on the 
programmer board.

2) Turn off the OB-1 and unplug the power cord.

3) Remove the bottom cover.

4) Examine the connectors on the programmer board.   The board itself
has a letter near pin 1 on each header, and on my unit, the connectors
had small labels near pin 1 as well, such as PRA, PRB, etc.   The connectors
are keyed, so that they cannot be inserted incorrectly.  The connectors on 
the new board are in similar positions to the original board, and the orientation
is the same.  They are also keyed, and are labelled using the silkscreen.

5) Unplug the connectors from the original programmer board.

6) Remove the battery from its holder.  It is no longer needed.

7) The battery connector and those for the two rear-panel Molex connectors 
are no longer used.   (The cassette interface and forcing a program externally
are no longer supported)   You may want to tie off these cables and connectors 
to keep them out of the way and keep them from touching any circuitry.   

8) Remove the six nuts and lock-washers holding the original programmer board.

9) Remove the programmer board and place it in an anti-static bag, or wrap it in 
aluminium foil.   Keep this board in case you ever want to re-install it.

10) Place the supplied nylon washers on the four standoffs closest to the rear panel, 
and place the new programmer board on these standoffs.  Fasten it with four of the 
six nuts removed earlier.

11) Examine one of the gray connectors, noticing that the holes are closer to one 
edge than the other, and one of them is blocked with a plastic plug for keying.

12) Place connectors A,B,C,D, and H onto the matching headers, with the key in the 
position of the missing pin.   Push the connectors all the way down.   The header
pins on the new programmer board are slightly shorter than on the old board, but they 
still make full contact.  This is why it's important to push the connectors all the 
way down.  Don't break them by pushing too hard.   Just make sure they are all the way
down.

13) With the OB-1 power switch off, plug it in, and get into a position to watch the 
LED's as it is turned on.   Turn on the OB-1.   You should see the LED's sweep to the 
right, then back to the left, and LED1 should remain lit.   If you don't see these
things, check to make sure that all of the connectors are seated properly.

14) Touch the Manual Mode pad and switch off osc2 main and sub and osc1 sub oscillator.  
Open the filter and turn off any modulation so that you have just a simple steady tone 
when you press a key.

15) Now you need to adjust the DAC reference voltage (VR) to match the value on the original
programmer board (which was also adjustable).   The oscillators were calibrated with VR
set to a specific voltage, so it's important to set the new board to the same value.  The
easiest way to do this is with a chromatic tuner.   First locate the gray 20-turn trimpot
on the programmer pc board, and the round metal slotted part which can be turned with a 
small screwdriver to adjust it.   

16) Turn the osc1 coarse freq pot fully counter-clockwise.  Play a C key and adjust the 
osc1 fine freq control to get a perfect C pitch.  Now turn the osc1 coarse frequency control 
clockwise and see if the notes get flatter or sharper the further you turn the control 
clockwise.   If they get flatter, that means the steps (and VR) are too small.   To increase
VR, turn the trimpot counter-clockwise 1/2 turn at a time.   To decrease VR, turn clockwise.
After you have made a small adjustment, repeat this entire step until the frequency steps 
are perfect semi-tones.   There is only one VR setting, so once you have the right value, 
both oscillators should have the correct steps.

Note: The VR setting does not affect how much the oscillator pitch changes when you play 
different keys.  It only affects the potentiometer voltages.

17) Install the bottom cover.