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Bad HP41 Time module - Gonzalo Fernandez (Spain) - 12-02-2006 I have a bad HP41 time module, can see the catalog of functions, but when I execute the CLOCK function (or SHIFT ON), the calculator powers off! Is not the calculator, I have tried it in an HP41C and HP41CV with same results.
thanks
Re: Bad HP41 Time module - gileno - 12-02-2006 New Batteries !!! :-)
Re: Bad HP41 Time module - Vieira, Luiz C. (Brazil) - 12-02-2006 Hi, Gonzalo; if you try TIME instead of CLOCK, does it happen the same? Let us know. Success and best regards.
Luiz (Brazil)
Re: Bad HP41 Time module - Gonzalo Fernandez (Spain) - 12-02-2006 Thanks, but I´ve already tried this with no solution. SHIFT ON powers off the calculator
Re: Bad HP41 Time module - Gonzalo Fernandez (Spain) - 12-02-2006 TIME always shows 12:00:00 AM It seems to me that the crystal quarts is broken, because I can see the catalog of functions but time doesn´t run
Re: Bad HP41 Time module - Les Bell - 12-02-2006 It's unlikely to be the quartz crystal itself, because those things are so simple - just a piece of rock, shaved to size, with two wires attached, basically. It's more lkely to be some other part of the oscillator circuit. Best,
--- Les Maybe... (was: Bad HP41 Time module) - Vieira, Luiz C. (Brazil) - 12-02-2006 ... a cold, broken solder. I agree with the fact that a quartz X-tal is somehow hard to be a deffective componnet, but in this case, if TIME returns 12:00:00 everytime, it tells me that the clock is not ticking. If the crystal is disconnected, a tinny little bit of well placed solder might solve the problem. In time: is the crystal of the time module a discrete component or would it be integrated, I mean, in the same package of the rest of the module's circuit? Anyone with a picture? Cheers.
Luiz (Brazil)
Re: HP41 Time module frequency - Klaus - 12-03-2006 The frequency is 32768 Hz. The manual mentions the frequency after the prescaler, the design specification of the time module states 32kHz, and I measured the clock of a HP-41CX fullnut to be sure.
Re: HP41 Time module frequency - Gonzalo Fernandez (Spain) - 12-03-2006 Thanks for the responses. The crystal is a discrete component, with a parallel attached resistor. Will measure the frequency and try to retouch the soldering points.
Re: Bad HP41 Time module - David Smith - 12-03-2006 The crystal is 32768 KHz. This is a common part and fairly easy to find. I have seen a couple of 41CX's with bad timers. The problem was the 22 megohm resistor.
Re: Bad HP41 Time module - Gonzalo Fernandez (Spain) - 12-03-2006 The crystal is good, I have tested it with a oscilloscope. The resistor is 30Meg. As soon as I power on the calculator, a sine wave appears in the crystal, but the time doesn´t advance. I will have to get a small microswitch (like the ones found in HP48GX memory cards) and mount it in the time module. I power on the calculator with the switch off (no resistor attached in the crystal), then I turn the switch on (now the resistor is in parallel with the crystal) and now the time advance and it seems the module function correctly. A strange behaviour, but at least the module works in this manner and holds the time even with the calculator powered off.
Thanks for all your responses
Re: Bad HP41 Time module - David Smith - 12-04-2006 I would try some different values for that resistor (10/15/22 meg). Mayby the crystal has aged some and needs a little extra drive.
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