IBM System/34 Maintenance Manual page 377

27-690 INDEX SENSE PTX OUTPUT SERVICE
CHECK
CAUTION
Always perform this service check with a diskette
inserted backward (with the label facing the hub pulley),
so that the LED (light-emitting diode) does not cause a
wrong service check or destroy the PTX.
1. Remove power and the 72MD unit (see paragraph
27-200).
2. Disconnect the drive motor AC power cable
0
and driver board connector J3
e.
DANGER
Voltage is still present at the power connector when
it is disconnected and power is on.
3. Set Power to I (operator panel).
4. Place the picker assembly to the rear of the unit.
5. Insert a diskette backward until it touches the
collet.
6. For the old style picker, connect the positive probe
of a multimeter (15 Vdc scale) to test pin TPB-14
• (+index) on the control card.
92
For the new style picker, connect the positive
probe of a multimeter (15 Vdc scale) to test pin
TPB-16 • (+index) on the control card.
7. For the old style picker, connect the negative
probe of the multimeter to test pin TPA-12 •
(ground).
For the new style picker, connect the negative
probe of the multimeter to test pin TPA-13 •
(ground).
8. Check the multimeter for a reading of less than 1
Vdc.
9. Install one end of a jumper to test pin TPB-2
0
(53FD PTX emitter).
10. For the old style picker, while observing the
multi meter, touch the other end of the jumper to
test pin TPA-11 • (+5 volts) several times. The
multimeter should read 2.5 Vdc or more when the
test pin is touched. (A wrong reading can occur
the' first time the test pin is touched.)
For the new style picker, while observing the
multimeter, touch the other end of the jumper to
test pin TPA-15 • (+5 volts) several times. The
multimeter should read 2.5 Vdc or more when the
test pin is touched. (A wrong reading can occur
the first time the test pin is touched.)
11. Repeat steps 9 and 10 with the jumper on test pin
TPB-1
CD
(33FD PTX emitter).
12. Set Power to 0 (operator panel).
13. Remove the jumper.
14. Remove the diskette.
15. Connect the drive motor AC power cable
0
and
driver board connector J3
e. .
16. Reinstall the 72MD unit (see paragraph 27-200).
27-690
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