The Museum of HP Calculators

HP Forum Archive 19

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HP-67 Power trouble
Message #1 Posted by benitoprat on 5 July 2009, 9:34 a.m.

Hi If I turn off the Off/On switch and put it On again, the HP-67 doesn´t work. Npt a single dot appears. If I remove the battery and put it on againwith the Off/On switch to ON it starts and works perfect, (even the Card Reader)

Please if someone knows how to fix this I would be very grateful

Best regards

      
Re: HP-67 Power trouble
Message #2 Posted by Michael de Estrada on 5 July 2009, 10:50 a.m.,
in response to message #1 by benitoprat

Try again with the AC adapter/charger plugged in. Could be battery not fully charged or poor battery connection. Also, could be dirty OFF/ON switch contacts.

            
Re: HP-67 Power trouble
Message #3 Posted by benitoprat on 6 July 2009, 9:02 a.m.,
in response to message #2 by Michael de Estrada

Thank you for your answer. I tried with the AC adapter/charger plugged in and with a fresh charged battery (I have an external HP battery charger) and still have the problem. Best regards Daniel

                  
Re: HP-67 Power trouble
Message #4 Posted by Michael de Estrada on 6 July 2009, 9:56 a.m.,
in response to message #3 by benitoprat

There are others on this forum who have a greater knowledge of this, and may have some ideas. The only thing I can think of is that the capacitors that are used in the LED circuit may be weak, and although the calculator ICs are getting powered, the LEDs are not. Why removal and then re-installation of the battery pack fixes this I do not know. Then again, I could be completely wrong on this, so it is just idle speculation.

Edited: 7 July 2009, 9:52 a.m.


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