HP Forum Archive 21

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Thank you, Geoff Quickfall Message #1 Posted by Geir Isene on 3 May 2012, 2:51 p.m. This worked wonders: Help with HP-41 keyboard issue.

Re: Thank you, Geoff Quickfall Message #2 Posted by Matt Agajanian on 3 May 2012, 3:04 p.m., in response to message #1 by Geir Isene Wait a minute! I'm a little confused here. According to the Archive thread you referenced, an HP-41CV was transformed into a CL. When I sent a message to Randy at FixThatCalc a month ago, he told me that because of the motherboard, only a CX can be upgraded to a CL. So, could someone clarify which 41s are suitable for CL upgrade?

Re: Thank you, Geoff Quickfall Message #3 Posted by M. Joury on 3 May 2012, 3:18 p.m., in response to message #2 by Matt Agajanian Nope. 41CV's work fine as donor bodies. You can probably find all the info you want here. Cheers, -Marwan

Re: Thank you, Geoff Quickfall Message #4 Posted by Ángel Martin on 3 May 2012, 3:24 p.m., in response to message #2 by Matt Agajanian Quote: could someone clarify which 41s are suitable for CL upgrade? Fullnuts.

Re: Thank you, Geoff Quickfall Message #5 Posted by M. Joury on 3 May 2012, 3:40 p.m., in response to message #4 by Ángel Martin There are a couple of other possible limitations. Beyond "Having a square cornered display" here is the relevant section from the V3 manual: Hewlett-Packard changed the display driver circuitry in the 41 series during production, and this change affected one component value on the CPU circuit board. The 41CL circuit board implements the component value used in later production units. Units with the correct display driver can be identified as follows: • If your 41C (not CV or CX) has a serial number starting with “1954” or larger it uses the correct display driver. • If your 41CV/CX has a serial number starting with “2003” or larger it uses the correct display driver. It is theoretically possible to use the 41CL circuit board with the older display driver, but this requires soldering an extra capacitor to either the 41CL circuit board or to the calculator main board. If you really want to upgrade a calculator that uses the older display driver, please contact us directly for details. In addition to the display driver change, Hewlett-Packard also experimented with a different method of connecting the CPU board to the main board. Unfortunately it is not possible to identify units that used this different connection method via the serial number. I hope it is ok to post this here. Cheers, -Marwan

Re: Thank you, Geoff Quickfall Message #6 Posted by Matt Agajanian on 3 May 2012, 4:41 p.m., in response to message #5 by M. Joury Okay, here's what I have: I've got a 41CV with a rounded display corners and serial number starting with 26 and another 41CV with a straight corner display with a serial number starting 24. Which 41CV qualified for a CL upgrade? Edited: 3 May 2012, 4:43 p.m.

Re: Thank you, Geoff Quickfall Message #7 Posted by M. Joury on 3 May 2012, 5:05 p.m., in response to message #6 by Matt Agajanian Not the one with rounded display. The other should work just fine. BUT, please note the following (also pasted in my earlier email): Quote: In addition to the display driver change, Hewlett-Packard also experimented with a different method of connecting the CPU board to the main board. Unfortunately it is not possible to identify units that used this different connection method via the serial number. Identifying such a calculator is a step in the installation process covered in the next section. Edited: 3 May 2012, 5:12 p.m.

Re: Thank you Geir: Matt check out this... Message #8 Posted by Geoff Quickfall on 6 May 2012, 7:55 p.m., in response to message #2 by Matt Agajanian Matt check this link: HP 41 donors suitable for CL CONVERSION. Cheers, Geoff Both my CL's are 1979 tall key HP 41Cs Edited: 6 May 2012, 8:02 p.m.

Re: Thank you Geir: Matt check out this... Message #9 Posted by Matt Agajanian on 6 May 2012, 11:32 p.m., in response to message #8 by Geoff Quickfall Hi Geoff. Thank you for the clarification. As I have one of each (a rounded- and square-corner display 41CV), I'm certain, at least the straight-edged one can get the CL treatment. Thanks for explaining why. Matt Edited: 6 May 2012, 11:33 p.m.

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