HP-67 Card Reader became very touchy

[Alevin]

Update, about the crd Error reading, in the HP-97.

After solving the issue in the HP-67, I went to the HP-97. I substituted the habitual suspicious cap, indicated by Teenix some post above. Out of the board it was not so bad, measured values were 44 nF, 0,3 Ohms ESR, Replacement new one has 45 nF 0,1 Ohms ESR. Look at attached pics. New cap on board, and new vs old caps,

Unfortunately it has not solved the issue. Still, when low battery is inserted, the cards are read, but when batteries are middle of full charged, it stops reading. It feels some squeak when batteries are full. When low batt, less o no chirp is found. May be when batteries are full they produces plenty of torque and the clutch is more prone to slip?

I got the HP-97 back in 2017, with the card reader gummy wheel already substituted by o rings, but I do not know if the clutch was fixed as well.

To make thing worse, during testing, the original idle gear, the was working fine like a champ, disintegrated several tooth. I have noted afterwards that the printed head gets blocked at 1/3 position. Probably this made lose the fragile idle gear.

This is the plan.

1) To replace the deteriorated idle gear, with nylon shapeways option. I will inform about my experience about in the proper threat (https://www.hpmuseum.org/forum/thread-15...inter+gear). The paper rollers seems to require also substitution, but I am afraid the required skills are beyond my limited capabilities and tools, ending with and inoperable printer. In any case this does not refer to card reader problems of the threat.

2) To fix the clutch with the drastic glue option, if inspection show slipping, assuming that it was not fixed when the O were introduced. Other clutch fixing options seems to be unpractical for me, i..e. uncertainty in procurement of wires or tubing in EU being the stuff recommended is in inches, whereas in here we have mm standards.


3) As the calculator reads and writes at low battery level, I will not try to play a with eccentric cam (in any case it not so easy to manipulate as in Hp-65 Hp-67). No speed potentiometer exits, so it will be kept as it is.

May be you have also some clue about another components, caps?, that could be checked in relation with the specific issue. Systematic replacement of all caps is not in my mind, under the principle: If it works, don’t touch. Indeed the Hp-97 worked fine, printing, and reading/writing cards (al least when low batt), before I tried to improve things, .-D