HP Forum Archive 16

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HP41CX Clock Anomaly Message #1 Posted by Jason on 13 July 2006, 12:02 a.m. Hi, My HP41CX has an unusual and baffling clock function problem - but I'm not sure if its a hardware problem or a simple setting problem - I suspect its hardware. When I activate the clock function via "SHIFT + ON", it displays the clock every second for 3 times only and stops on the 3rd time displayed. eg "SHIFT + ON" displays "3:01:25 PM" "3:01:26 PM" "3:01:27 PM" <------ this then remains displayed on screen - no further increments are displayed. The clock normally is supposed to display the time continuously every second, but each and every time it only displays time for 3 seconds and stops changing after 3 seconds. The clock itself is still incrementing correctly irrespective of the display because if you again activate the clock again it shows the correct time but only displays the changes for 3 seconds again and halts changing the dislay on the third time display eg "SHIFT + ON" 30 seconds later displays:- "3:01:55 PM" "3:01:56 PM" "3:01:57 PM" <------ this then remains displayed on screen again - no further increments are displayed. All other calculator functions are OK and it just seems to have this one anomaly with the clock. A complete reset has no effect - is this just a weird hardware problem (which I suspect) or is it a setting problem with the clock. Thanks Jason

Re: HP41CX Clock Anomaly Message #2 Posted by David Smith on 13 July 2006, 11:04 a.m., in response to message #1 by Jason I would suspect something corrupted in memory. First turn the machine on, start the clock, and remove the batteries before it stops. Then do a hard reset (BACKSPACE+ON) and reset the clock. If this does not work, you probably have a hardware or ROM problem. One thing to try is taking the machine apart and scrubbing the circuit board with 91%+ isopropyl alcohol. Pay attention to the area in the corner of the board with the 22 meg resistor and small cylindrical clock crystal and the chip they connect to (assuming a fullnut 41CX)

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