Re: HP 82104A card reader, fork-shaped brass tongues, REPAIR PROBLEM Message #9 Posted by Diego Diaz on 9 Apr 2010, 10:53 a.m., in response to message #8 by Markus Sanke
Hi Markus, Ignazio, all...
(Ignazio, thanks for asking, I'm fine and hope you're also doing well. Currently in the Dominican Republic taking some weeks of rest... well, more or less... ;-)
To your questions Markus:
The first actuator to operate is the (so called) motor driver. In fact this is properly a Card Insertion detect switch by means of which the internal circuit is waked up and, if necessary, the 41 CPU will also be waked up. It is the CPU that in the end instructs the Card Reader circuit to turn the motor on.
Once the card is running through its path, the head actuator should make contact at the point in which the card reaches the head tip.
Here is an image of how the contact blade should look like. Is it obviously not to scale, and drawn from my head so please take it with a grain of salt... :-)
The long blade should be *very slightly* (less than pictured) bent upwards. Just enough to settle in place with very little pressure on its ends. This bending should look convexe along the blade. In your pictures a small concave bending shows up just beneath the actuator hinge and I think this must be corrected.
Note that this is not the "factory" shape, but I found it easier to produce that small banding than get it back to full straight when a repair is needed.
The actuator could in fact has gone so badly worn out that it can no longer tilt enough to activate the switch. This looks quite improbable to me though. So let's try the easier and if it doesn't fix the trouble will look further.
Hope you can get your Card Reader back to work soon.
Cheers.
Edited: 9 Apr 2010, 11:18 a.m.
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