HP HP-97 - Page 148

[ evs CORVALLIS DIVISION 97101
n
PACKARD SERVICE NOTE
Page 5 of 7
(...continued)
Supersedes:
* Magnets can be obtained by breaking apart a defective motor assembly.
The card can be erased by passing it over the flat side of the
magnet.
** Part Number "8500-0790".
*** We use Dow-Corning Molykote G Paste, Cat. No. 87500-16.
3. The last problem to be discussed concerns noisy card reader motors.
The thrust bearing on the end of the worm gear is designed to carry
the thrust force when the motor is running. If the worm gear is
pressed onto the motor very hard, the two bearing surfaces will never
touch. The force will be riding entirely on the motor bearings and this
causes noise. Make sure the worm gear will contact the thrust bearing
by pulling it away from the motor slightly before installing it in
the card reader.
If the thrust force is riding on the ball bearing at the tip of the
worm gear, rather than motor thrust bearing, the current drawn by the
motor will be at a minimum and the motor speed will be at a maximum.
This is important when adjusting motor speed on a card reader, to insure
that card thickness and condition have a minimum effect on motor speed
variations. This adjustment will have a minor impact on the noise of
the card reader and will enhance the long term performance.
When installing the motor, if the worm gear and coupler are pulled
out a bit before installation, the force will be on the thrust bearing
and the opposite motor bearing. If the worm gear is pushed towards
the motor a small distance after installation, the thrust force will be
entirely on the thrust bearing as is desired. This adjustment will
help toward maintaining proper operation of the card reader.
(continued...)
For more information, contact the Service Engineering Manager, Corvallis Division—1000 N.E. Circle Bivd., Corvallis, Oregon 97330
Telephone (503) 757-2000 ¢ TWX # 510-596-0683
Printed in U.S.A.