ARMY TM 5-6675-238-14
MARINE CORPS TM 08839A-14/1
Table 8-8. Tape Reader Testing and Troubleshooting Procedure - Continued
Malfunction indication/
Test procedure
Normal indication
corrective action
5.3b.
5.3c.
5.3d.
Connect oscilloscope chan-
nel A probe ground return
to ground (TB2 terminal 10;
TP5) and connect same
channel A probe to Al card
cage
in M. (Use card ex-
tender)
Slowly adjust A1R3 clock-
wise (not more than 10
turns) until the positive
pulse period just starts to de-
crease or the pulse disap-
pears; adjust counterclock-
wise until the pulse period
stops increasing
For each of the A1 card re-
sistors listed in this step, ad-
just as follows:
Slowly adjust A1 resistors
clockwise not more than 10
turns) until the positive
pulse period just starts to de-
crease; then, adjust resistors
counterclockwise until the
positive pulse period stops
increasing; then, turn the re-
sistors
one-quarter
turn
clockwise
N O T E
Voltage out of tolerance: Replace A1
If pulse is within tolerance, but
Period T3 out of tolerance: Perform
will not adjust, turn resistor clock-
steps 5.2e and 5.2f again, then repeat
wise 12 turns, then counterclock-
this step. If still fails, replace A1. If
wise 6 turns.
still fails, replace B1
Oscilloscope indicates waveform
C of figure 8-5
N O T E
Waveform C and D in figure 8-5
should only be observed when the
tape reader is running either for-
ward or reverse (use MEMORY
LOAD or REVERSE switch-indi-
cator) in the all-holes area of the
punched tape.
Each waveform
must be checked in both the for-
ward and the reverse direction.
Waveform D in figure 8-5 (refer to Waveform not in tolerance: Replace A1
note in step 5.3c)
For each waveform measured and found
to be out of tolerance, adjust the cor-
responding resistor to bring the wave-
form into tolerance. If this is not pos-
sible, replace A1
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