Flakey HP41CX clock?



#6

Anyone else had this problem? I have two HP41CX's, one is a halfnut. Both seem to suffer from a lack of robustness in the clock department. On powering up, I sometimes find the clock has reset itself to 00.00.00 etc. Yet the stack registers are all preserved ok. Are the clock registers less robust in the face of minor battery interruptions or is there another factor at work? Similarly, if the battery is down - "BAT", the clock by design won't come on - fair enough. But if one inadvertently asks for the clock display, surely this should not lead to a clock reset. How long can the clock keep time 'batteries out'. The regular memories go on for days in this condition.


#7

>>>Anyone else had this problem? I have two HP41CX's, one is a halfnut. Both seem to suffer from a lack of robustness in the clock department. On powering up, I sometimes find the clock has reset itself to 00.00.00 etc. Yet the stack registers are all preserved ok. Are the clock registers less robust in the face of minor battery interruptions or is there another factor at work? >> Similarly, if the battery is down - "BAT", the clock by design won't come on - fair enough. >> But if one inadvertently asks for the clock display, surely this should not lead to a clock reset. How long can the clock keep time 'batteries out'. The regular memories go on for days in this condition. <<

Boy, I'm sorry. It's been quite a while since I played with one of these to any great extent. Another possibility is get your manual out and double check all the user flags status. Also, much less likel;y, there may be some quirk in a program causing this condition even if it is totally unrelated to any time function. Good luck and let me know if anything happens.


#8

I just subjected my 41CX to a 10 second power disruption (similar to changing batteries I guess) and the clock continued to run. (well, I didn't lose the time)

How long did it take to lose the time?


#9

Thanks Steve. For the '85 CX halfnut with regular N cells, time sometimes has been disrupted without even removing batteries, clock will read e.g. 3 am, implying it got reset on its own 3 hrs ago. For the '83 CX with the rechargeable pack (83120A) when the low battery icon comes on, if I inadvertently request clock time the display blanks (by design?) to not show clock when the battery is low, HOWEVER after recharging the clock has reset itself. Maybe I'm just unlucky enough to have two different problems, but I notice the stack registers are always retained in both cases when this this happens - so why does the clock register fail first? It doesn't seem to relate directly to a 10 second or longer battery disconnect.


#10

Last night I went looking for my CX manuals in order to try to find out how long the clock would work without batteries (and other conditions). Unfortunatly the manuals have gone into hiding :-(

Your problem does sound a bit like a fault to me. Perhaps the capacitor in the CX that holds power during battery replacement is dead or dieing and it is causing the problem?

But to two CX's that you happen to own??? And as to why the rest of the calculator doesn't die....?

Do you have any corrosion on the battery contacts?

Has the calculator been repaired or modified?

I don't think I can offer even a slightly educated guess. It's weired. Keep us informed if you do find the cause.


Possibly Related Threads...
Thread Author Replies Views Last Post
  HP Prime - Revision Suggestion - Setting the Clock Bill Triplett 5 587 11-15-2013, 12:36 AM
Last Post: Joe Horn
  Prime incase anybody missed the clock Dougggg 5 519 10-19-2013, 04:05 PM
Last Post: Geoff Quickfall
  Using your HP-65 as a clock! Don Shepherd 24 1,545 10-08-2013, 11:53 AM
Last Post: Don Shepherd
  HP41CX: Strange serial #... Stephan Matthys 1 281 09-13-2013, 01:38 PM
Last Post: Stephan Matthys
  WP-34s clock program Andrew Nikitin 8 638 06-09-2013, 11:20 PM
Last Post: Andrew Nikitin
  Cool math clock Bruce Bergman 28 1,872 04-10-2013, 03:13 AM
Last Post: Siegfried (Austria)
  hp clock does not talk to hp 71 Hans Holzach 15 913 07-29-2012, 04:13 PM
Last Post: Hans Holzach
  Using PIL-BOX & ILPer to Transfer Programmes from PC to HP41CX? Michael Lopez 5 495 06-25-2012, 09:31 AM
Last Post: Michael Lopez
  OT: Mechanical CPU clock Ethan Conner 1 268 04-19-2012, 01:23 AM
Last Post: Mike Morrow
  [WP34s] Accurate Clock Katie Wasserman 1 243 04-08-2012, 01:25 AM
Last Post: Walter B

Forum Jump: