HP Forum Archive 15

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HP-41 contrast adjustment? Message #1 Posted by Geir Isene on 26 Dec 2005, 12:54 p.m. Seeing the listing from the AlphaRom, it seems to be possible to adjust the contrast of the HP-41, is that so? Is this the only way?

Re: HP-41 contrast adjustment? Message #2 Posted by Howard Owen on 26 Dec 2005, 1:16 p.m., in response to message #1 by Geir Isene I think it's only possible with the halfnut models.

Re: HP-41 contrast adjustment? Message #3 Posted by Vieira, Luiz C. (Brazil) on 26 Dec 2005, 2:31 p.m., in response to message #2 by Howard Owen HI Howard, guys; as far as I read about, you are correct. Either full lower-case alphabet or contrast adjustment are only possible with the half-nut units. As an example, Angel's Sandbox ROM has headres that can only be fully read with halfnut units. And if I am not wrong, Angel's Sandbox ROM (would that be the Toolbox?) has a contrast adjustment function. Best regards. Luiz (Brazil)

Re: HP-41 contrast adjustment? Message #4 Posted by Geir Isene on 26 Dec 2005, 3:24 p.m., in response to message #2 by Howard Owen Is it possible to make a halfnut from a halfnut main board and a fullnut casing?

Re: HP-41 contrast adjustment? Message #5 Posted by Howard Owen on 26 Dec 2005, 4:04 p.m., in response to message #4 by Geir Isene If you swap out the daughter card and the mainboard, including LCD, together, I don't see why not.

Re: HP-41 contrast adjustment? Message #6 Posted by PeterP on 26 Dec 2005, 5:42 p.m., in response to message #5 by Howard Owen i think there are a few threads on this one here, but I think you are right - bascically one has to change everything. Tony Duell, aside from all the other gurus here, would know all about it I believe... The one thing I'm not sure about is if the keyboard can stay. Also, changing the LCD - which has the display drivers included. might be a pain to do. ONe migh tbe better of selling the fullnut and purchasing a halvenut. The price-difference, even via ebay, should be somewhere between 0 and 35 USD... Cheers Peter

Half+Full nuts?(was: HP-41 contrast adjustment?) Message #7 Posted by Vieira, Luiz C. (Brazil) on 27 Dec 2005, 12:12 a.m., in response to message #4 by Geir Isene Hi, Geir; I have done such 'transplantation'. I have a halfnut HP41CV with a bad RAM (shows up only 63 registers) inside an original HP41C fullnut case. As mentioned in this thread, all of the inner package must be transplanted, LCD assembly included. Look at the picture below: After removing the entire 'guts' from both calculators, it is necessary to cut out some small posts in the fullnut case (shown as black spots in the picture) prior to settle the halfnut main PCB. This is due to the fact that the halfnut main PCB does not have all small holes available in the fullnut main PCB. Appart from that, evertyhing else fits perfectly fine. The rounded-edge LCD frame is actually in the LCD assy itself, so it goes with the whole package. Hopes this helps a bit. Cheers. Luiz (Brazil)

Re: HP-41 contrast adjustment? Message #8 Posted by Miki Mihajlovic on 26 Dec 2005, 3:36 p.m., in response to message #1 by Geir Isene Sandbox (CTRST, CTRST?, CNT+, CNT-) and Hepax (CTRAST or HEPAX 005) are the only two modules to my knowledge that have functions to adjust the contrast of LCD on halfnut models only.

Re: HP-41 contrast adjustment? Message #9 Posted by Geir Isene on 26 Dec 2005, 5:03 p.m., in response to message #8 by Miki Mihajlovic When contrast is adjusted, does it stay adjusted after the module is removed?

Re: HP-41 contrast adjustment? Message #10 Posted by PeterP on 26 Dec 2005, 5:39 p.m., in response to message #9 by Geir Isene yes.

And... (was: HP-41 contrast adjustment?) Message #11 Posted by Vieira, Luiz C. (Brazil) on 27 Dec 2005, 12:20 a.m., in response to message #10 by PeterP I tested once, and the contrast set is kept even after a [MEMORY LOST] procedure, module(s) inserted or not. Just to add this bit... Cheers. Luiz (Brazil)

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