The Museum of HP Calculators

HP Forum Archive 19

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Adjusting card reader eccentric screw
Message #1 Posted by Ed Sowell on 15 Mar 2010, 12:32 p.m.

I would like to try the adjustment method based on motor current draw as described in the Service manual. Since my calculator is in pieces can I disconnect the motor leads and use a 1.5v(?) battery in the test?

      
Re: Adjusting card reader eccentric screw
Message #2 Posted by Geoff Quickfall on 16 Mar 2010, 1:11 p.m.,
in response to message #1 by Ed Sowell

Thats how I do it and I have yet to have a problem.

Cheers, Geoff

            
Re: Adjusting card reader eccentric screw
Message #3 Posted by Ed Sowell on 16 Mar 2010, 4:25 p.m.,
in response to message #2 by Geoff Quickfall

Just to be sure, is the motor test voltage supposed to be 1.5 volts? I recall having seen that somewhere but now can't find it.

      
Re: Adjusting card reader eccentric screw
Message #4 Posted by Ed Sowell on 17 Mar 2010, 4:29 p.m.,
in response to message #1 by Ed Sowell

The spec says I should adjust the eccentric screw to get 180 +/- 20 mA while holding the card from going through. The lowest I can get is about 330 mA. When the motor is running freely w/o card it draws about 190-205 mA. This is while using a nominal 1.5 volt battery, which actually is about 1.4 volts, with a digital multimeter in series.

I am using O-rings bought from the eBay seller.

Is this typical?

Edited: 17 Mar 2010, 4:35 p.m.


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