Radio Shack TRS-80 Service Manual page 117

TRACK
~~
ALIGNMENT
Track 00 Switch Adjustment
1. Connect Scope:
Channel A to pin 1 of Plug 11
Vert. to 2 volts/div.
Time Base to 10msec.
Trigger internal channel A, DC coupled
2. Step between tracks 02 and 03.
3. Loosen track 00 switch mounting screw and adjust
until switch activates between tracks 02 and 03.
Tighten mounting screw.
Track 00 Stop Adjustment
1. Connect scope as in Head Radial alignment.
2. Insert alignment diskette and read track 013.
3. Back off the track 00 stop screw two turns. Slow·
ly
turn
the track 013 stop screw in until the output
amplitude shown on the scope starts to decrease.
Back the track 00 stop screw out until the ampli-
tude stops increasing. Back the track 00 stop screw
out one-half turn from,this point.
TRACK IN STOP SCREW
(0.050" ALLEN WRENCH)
FIGURE 13. TRACK
gg
STOP ADJUSTMENT
INDEX SECTOR ADJUSTMENT
1. Set Scope:
Vert. at 0.2 volts/div
Time Base 50,U.sec/div
2. Insert alignment diskette and read track 01. Scope
display should show 0 volts AC trace for
200.usec
±
5g.usec.
If waveform is outside of spec., loosen
the index sector light mounting screw and adjust
to spec.
3. Open and close the Drive door and re-verify the
index sector timing.
I
IV
TIME SCALE. SO"sec/DIV
FIGURE 14. INDEX SECTOR TIMING
HEAD MODUl£
D
IIJIlll
SENSOR RETAINING SCREW ADJUSTMENT
110
FIGURE 15. INDEX ADJUSTMENT