HP Forum Archive 16

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Disassemble a 48S, How do I do? +Other Q's Message #1 Posted by Tomas Larsson on 22 Sept 2006, 2:12 a.m. How do I disassemble a HP48S without breaking it. Will try to fix the keyboard.. Since I don't dare to use my 41CV anymore, I thought to replace it with the 48S, but it seems like the keyboard needs to be serviced a little. The ON-button does not work most of the times. ANother question I have, is it same display on the 48S as on the 38G's. Beacause when i manage to get the 48 working, the dispaly seems a little dim, and I have a couple of 38G's that I bought by mistake, didn't realice that they were non-rpn ones, and while I'm on it i could swap the display at the same time. Thanks TOmas

Re: Disassemble a 48S, How do I do? +Other Q's Message #2 Posted by Tomas Larsson on 22 Sept 2006, 8:27 a.m., in response to message #1 by Tomas Larsson Never mind about the disassembly, found it in the links-section. The Display question though is still relevant.

Re: Disassemble a 48S, How do I do? +Other Q's Message #3 Posted by Klaus on 22 Sept 2006, 8:58 a.m., in response to message #2 by Tomas Larsson Regarding keyboard service: Take out the batteries, and put a drop of * on the side of the Enter-key, so that it cleans the contacts. Let dry for a day. I think the keyboard is fixed with heat-stakes, and barely serviceable. * = I think most people use isopropyl alcohol. I use distilled water, I don't know which is better. EDIT: I think the correct name for isopropyl is '2-propanol'. I think you can use any alcohol that doesn't leave stains after drying. Remember that alcohol does not solve some substances that water does, and vice versa. Edited: 22 Sept 2006, 9:35 a.m.

Re: Disassemble a 48S, How do I do? +Other Q's Message #4 Posted by Tomas Larsson on 22 Sept 2006, 12:44 p.m., in response to message #3 by Klaus After a little bit of investigation, have not disassembled it yet, it seems that it is the connection between the keybord and the pcb that is causing the keyboard problem. I guess that cleaning is required, however, question is oif that solves the kontrast problem I have on the LCD. If I Turn upp the contrast the whole lcd goes black and I cant barely read the text, if i turn it down, I cant barely read the text as well, and it is very sensitive to the angle I lookj at the display, I can only see the text if i look at a 45 deg angle.

Re: Disassemble a 48S, How do I do? +Other Q's Message #5 Posted by Han on 22 Sept 2006, 6:54 p.m., in response to message #4 by Tomas Larsson The HP48S and HP48SX simply had very bad (compared the the G/GX) LCDs. There is nothing you can really do except for replacing the screen with a better one. Some useful links: http://www.math.uiuc.edu/~handuong/hp48/open/ http://www.math.uiuc.edu/~handuong/hp48/repair/ And here's what an HP48SX should have looked like since day 1: Edited: 22 Sept 2006, 6:58 p.m.

Re: Disassemble a 48S, How do I do? +Other Q's Message #6 Posted by Tomas Larsson on 22 Sept 2006, 8:30 p.m., in response to message #5 by Han Yeah, ok obviously the 38G's I have has a better screen, but are they compatible, I gladly scrap one of the 38's to get a better screen on the 48

Re: Disassemble a 48S, How do I do? +Other Q's Message #7 Posted by Han on 23 Sept 2006, 1:10 a.m., in response to message #6 by Tomas Larsson I believe they are the same. If you look at: http://212.1.43.18/detlef/38GUpgr/hp38upgr.html you will notice that the HP48G and HP38G differ only in the card slot connectors, ROM, and RAM chips. If you can dissassemble an HP38G (almost same as HP48 method) and look at the LCD connector side, you can know for sure as opposed to just guessing like I am.

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