HP Forum Archive 16

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Strange HP-67 repair ... Help Please Message #1 Posted by jbssm on 22 Oct 2006, 4:47 p.m. Hi all, I was fixing a HP-67 card reader and I was successful in that. I tested the calculator and card reader before assembling it again and all went well. But after putting the screws on, the calculator doesn't work correctly anymore, when I turn it ON, I hear the card engine motor for about 0,25 sec. and then the word Error appears in the display, if I press any key the same thin happens again. I disassembled the calculator and it stated working again ... but if I squeeze it a bit I get the bad symptoms again. I don't have the minimum clue on how to solve this (I mean for good, going to the core of the problem), can anybody help me?

Re: Strange HP-67 repair ... Help Please Message #2 Posted by Steve Borowsky on 22 Oct 2006, 7:51 p.m., in response to message #1 by jbssm First of all, you weren't successful, since you didn't end up with a working card reader as a final result. Also, i'm a bit puzzled how you could effect a partial repair yet not have the slightest clue about this problem. In that case, can you tell what you actually fixed, what was wrong with it before? Can you be sure you didn't break something else when you fixed the original problem? You really have no clue? Do you know how the spring metal switches engaged by the card work? Do you understand the function of the nylon balls?

Re: Strange HP-67 repair ... Help Please Message #3 Posted by jbssm on 23 Oct 2006, 8:13 a.m., in response to message #2 by Steve Borowsky Hello, I know the repair mechanism quite well, I've fixed some by now. The card reader (as is the all unit) IS WORKING if I don't put too much pressure on the unit. It reads and writes correctly until I close the unit and put the screws on. I know what the nylon balls are for, but unlike in the HP-97 I don't know any way to test them for the correct adjustments with the calculator disassembled (in the HP-97 I could just use an Ohm meter and check if the contacts were with the right pressure point so that when I inserted a card they started to make the needed connection). While fixing the unit I bent one of the copper contacts (one of the 2 lower ones that are slightly raised) but now I putted it back in place. I hope this helps to understand the problem better.

Re: Strange HP-67 repair ... Help Please Message #4 Posted by Randy on 23 Oct 2006, 8:42 a.m., in response to message #3 by jbssm My, that previous response was a great help, wasn't it? Gee, let's see, I have no solution but I'll criticize you anyway. I can get that kind of help from my wife, thank you very much ;^) Your problem is contact adjustment. The motor start contact is out of position, it is too high. Any case distortion causes the motor to turn on. Quote: I don't know any way to test them for the correct adjustments with the calculator disassembled It is very simple. Use a metal straight edge** held across the contacts. Connect one end of the ohm meter to the straight edge, the other to the contact plate. Adjust the same as the 97, tighten until contact is made, then reverse by 1/8 turn. Fiddle as necessary for proper operation. Great fun. Beats removing and installing 8 screws to test each time. ** = Ruler, scale, narrow metal bar, whatever you have that is flat. The bar can be no wider than one contact width. Edited: 23 Oct 2006, 8:48 a.m.

Re: Strange HP-67 repair ... Help Please Message #5 Posted by Steve Borowsky on 23 Oct 2006, 9:57 a.m., in response to message #4 by Randy Quote: My, that previous response was a great help, wasn't it? Gee, let's see, I have no solution but I'll criticize you anyway. I can get that kind of help from my wife, thank you very much ;^) You're right, sorry jbssm.

Re: Strange HP-67 repair ... Help Please Message #6 Posted by jbssm on 23 Oct 2006, 5:46 p.m., in response to message #5 by Steve Borowsky Ei, no problem it's ok, I fixed it in the end :)

Re: Strange HP-67 repair ... Help Please Message #7 Posted by jbssm on 23 Oct 2006, 5:45 p.m., in response to message #4 by Randy Thank you :) It worked, the metal ruler thing is indeed a nice trick and with it I managed to get it going. Thank you again.

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