> Service Data
> This page details DAC trim and Tune Test procedures for the Six-Trak.
> This information is from the SCI's Manual No. TN610-0. It is posted for informational purposes only, and is in no way to be used as a replacement for the service manual.

> DAC Trim

> > 1. Remove the cover and let the unit warm-up for at least five minutes.
> > 2. Hold CONTROL RECORD and press SELECT #7. This sets the DAC to 0V.
> > 3. Set DVM to read mV .000
> > 4. Measure voltage at TPA. An offset of greater than +/- 0.9 mV is out of specification.
> > 5. If the offset is positive, add the offset value to 1 mV. If the offset is negative, subtract the offset value from 1 mV.
> > 6. Connect DVM to TPB and trim R1205 to the value figured in previous step, +/- 0.1 mV.
> > 7. Reseal the trimmer.

> Test Tune

> > In the tune test, each voice oscillator is checked against A-440. The error is displayed on the LED display (00-99), with negative values being indicated when all three PROGRAM, PARAMETER, and VALUE LEDs light. Three display digits equals one DAC bit. All voices must read within two DAC bits (six digits) of each other for each key tested. Otherwise may indicate a bad voice.
> > 1. If the 610 [Six-Trak] is Rev. A (serial numbers 1-900), a small modification maybe required (or may have already been performed):

> > > a. Cut trace at U146-2.
> > > b. Jumper U146-2 to U146-6.

> > 2. Hold CONTROL RECORD and press SELECT 9. (enables the tune test)
> > 3. Center the PITCH wheel.
> > 4. Hold CONTROL RECORD and press SELECT 3. (initalize PITCH wheel)
> > 5. Hold CONTROL RECORD and press SELECT 8. (selects the basic patch)
> > 6. Hold CONTROL RECORD and press SELECT 6 (manually tune) If when doing this procedure a voice is found to be out of the six-digit range, manually return and check the voice agian. If the voice then tunes fine, accept it but keep your eye on it for unreasonable drifting.
> > 7. While holding C2, watch the display, and adjust MASTER TUNE for the closest indictaion to 00. (The knob will operate in units of three). After adjusting, do not readjust unit the test is finished.
> > 8. While in the tune test, pressing the same note advance the voice assignment so you can test all six voices one after the other by just pressing the key.
> > 9. Check that all voices are within six digits of each other (at C2).
> > 10. Check all voices at each of the white keys in this octave and at C3 and C4 (highest key).
> > 11. Select PARAMETER 00 COARSE FREQUENCY, and adjust its value to maximum (48).
> > 12. Check each voice at each C.
> > 13. Check each note in the top octave.
> > 14. If the display read +/- 99, the voice tuning it too far out of range for the computer to measure.
> > 15. To exit test, CONTROL RECORD + SELECT 9, or reset.

> Back to NoteIt's Main page
© 1996-2000 noteit@juno.com