HP HP-97 - Page 113

HP-97 Component-Level Maintenance
Table 4-15. Card Reader Troubleshooting Procedure (Continued)
STEP ACTION
c. Monitor the motor switch (TP9 to If the oscilloscope shows
TP8). Turn the motor switch ad- clean switch action, go to step
justing screw until the trace 14,
goes off the screen. Then back
the screw off 1/2 turn. NOTE
After checking all three
switches, if any switch did
not show clean switch action,
remove the PC board:
O clean the contact points
with a soft pencil eraser;
o degrease the contacts with
Freon FT or denatured alco-
hol. Wipe with a soft tissue.
o If any of the contacts are
bent, replace the whole leaf.
0o Reassemble the PC board.
o Repeat step 13.
14,
Mount the card reader on a
fold-apart tester ET-9613-91M.
Measure the head resistance. Across HA -- 40 to 60 ohms;
Across HB -- 40 to 60 ohms.
The difference between HA and
HB =< 3 ohms.
HA to ground => 1.65 Kohms
HB to ground => 1.65 Kohms
If the resistances are within
limits, go to step 15.
If not, replace the head.Then go
to step 15.
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