|Re: Problems rebuilding a 41c Card Reader|
Message #6 Posted by Vieira, Luiz C. (Brazil) on 25 May 2003, 5:52 p.m.,
in response to message #5 by Randy Sloyer
Hi Randy, guys;
I am not sure, but is there any solid-state switch that would turn motor ON and allow it to go OFF after a few seconds? I think the only common line on it is the "power line".
A few days ago I got the following problem: an HP41 that would turn ON, blink the 0.0000 and than it yould turn off and refuse itself to go ON again. I opened it, clenaed the contacts and rebuilt it. Same problem.
I took the batteries of another HP41 and it did not even switch to NO. I cross-tested the batteries and felt myself confused: the problem was in the batteries.
I tested each one of them and found 1.38 to 1.48 Volts eanch, but when nI tested for current, one of them got less than 1mA, others could go more than 180mA. I placed the "bad" pack back and measured voltage by the small golden balls used for external DC power connection. Voltage was fine till I press ON key: it would drop to about 2.5 V (high resistence from bad battery) while LCD would blink the 0.0000 and then the calcualtor shoot-off. I changed the batteri and everything is fine, now.
What I mean is that electrical connection with bateries is achieved by the HP41's I/O connector, and batteries (+) and (-) lines go stragiht to any external devices. This means there is no way to cut off power to the devices by solid-state control; how come the card reader motor stops working? Are batteries O.K. when extra charge occurs?
Just a suggestion.
Luiz C. Vieira - Brazil