Sequential PROPHET-600 - 4-3 ARPEGGIATE ASSIGN

1. Switch power off and disconnect the power cord.
2. Remove U310 (2764 version SIX.0.0). Replace with SCI Part No. Z-1004 (2764
Version SIX.0.2).
NOTE: It should be possible to do the following without removing PCB
3. R emove all components and desolder holes with a vacuum syringe, to
allow easy insertion of replacement parts.
3. Locate and remove R305 (39K) and replace with 24K (R-073).
4. Locate and remove R306 (15K) and replace with 6V Zener diode (D-006). Observe
polarity. This diode becomes D315.
5. Add D316 1N914 (D-005) from D303 to D311 as shown. Observe polarity. Insulate
leads with tubing.
6. Add R335 150K between D311 and ground at the battery, as shown.
1-12 WHEEL ALIGNMENT
NOTE: Mechanical wheel alignment must be followed by the calibration routine, step
on page 1-5.
See Figure 1-15. The wheel rotation is limited by two molded stops on the wheel. When
replacing with a new wheel (SCI #M-352). be sure the limiting stops are correctly
oriented.
The PITCH wheel is supposed to be set to 2.5V (half of its 5-V range) when centered.
So while measuring the wiper voltage, use a screwdriver to trim the shaft of R1 to
read close to 2.5V. Move wheel up and down, trimming for best repeatability of this
reading. Then tighten the set screw.
The MOD wheel must be able to turn off fully. To trim, simply make sure the wiper is
fully grounded when the wheel is fully down. Then tighten the set screw.
1-14 TM600A 7/83