HP Forum Archive 19

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35s Modification Message #1 Posted by Hugh Evans on 20 Apr 2010, 2:32 p.m. I recall some discussion in the past regarding modification of the 35s. Given the relative ease of disassembly, good keys, and an attractive form factor is anyone up for using the case and keys to make a new machine? All I'm proposing here is a new LCD and PCB with perhaps a more capable processor, more memory and USB/some form of IO. I think this should be kept as simple as possible and would estimate a very nice mod kit to accomplish this could easily run $50. Anyone interested?

Re: 35s Modification Message #2 Posted by PeterP on 20 Apr 2010, 3:37 p.m., in response to message #1 by Hugh Evans I'd buy a mod kit for 50 bucks to add I/O

Re: 35s Modification Message #3 Posted by Gene Wright on 20 Apr 2010, 4:03 p.m., in response to message #2 by PeterP I'm in for $50.

Re: 35s Modification Message #4 Posted by Egan Ford on 20 Apr 2010, 4:36 p.m., in response to message #3 by Gene Wright Me too. If I like the mod I'll probably get another.

Re: 35s Modification Message #5 Posted by Valentino Ducati on 4 May 2010, 3:54 a.m., in response to message #4 by Egan Ford I'm in, also for more then US$ 50,00. Depending on the updates I'm getting. Is there any chance to get also a "hp standard" IrDA connector, mainly for print output to the beloved 82240 printer? Thank you anyway for the efforts. Valentino

Re: 35s Modification Message #6 Posted by Walter B on 20 Apr 2010, 5:12 p.m., in response to message #1 by Hugh Evans How about putting the same into a 30b? It's smaller and has a full row of keys below of the display, so soft keys are easily done with a reasonable LCD. Just my 0.02 Euros.

Re: 35s Modification Message #7 Posted by DaveJ on 20 Apr 2010, 5:41 p.m., in response to message #1 by Hugh Evans It was Jeff.O who did some early work on this "Phoenix 35sx" project back in 2007 and posted photos, got sample LCDs, and even did a DXF of the required board size and holes etc IIRC it wasn't trivial to disassemble and required drilling out a bunch of heat stakes. If so, that means reassembly of a new PCB would not be trivial either. So it looked pretty messy from a physical hardware point of view. Dave. Edited: 21 Apr 2010, 5:44 p.m. after one or more responses were posted

Re: 35s Modification Message #8 Posted by Bart (UK) on 21 Apr 2010, 4:51 a.m., in response to message #7 by DaveJ Quote: IIRC it wasn't trivial to disassemble and required drilling out a bunch of heat stakes. If so, that means reassembly of a new PCB would not be trivial either. Looking at Jeff O.'s post linked by Reth, the assembly looks similar to the HP-50g which I have taken apart and the small screws are easily put back into the shaved-off stakes and hold very well.

Re: 35s Modification Message #9 Posted by Hugh Evans on 21 Apr 2010, 12:58 p.m., in response to message #7 by DaveJ From the pictures the process doesn't look that bad, certainly much easier than a pioneer for example. I'll pick up another 35s and a 30b to document the dissection and put together some CAD drawings. My suspicion is that replacement of the PCB and LCD will be reasonable enough to be worthwhile. This obviously doesn't need to be too high-end. I think most people would be happy with something powerful enough to emulate saturn. Even 1MB of memory would be extreme in this application.... And a nice high contrast reflective LCD should complete the picture. I'll post progress as soon as I can.

Re: 35s Modification Message #10 Posted by Jeff O. on 21 Apr 2010, 4:05 p.m., in response to message #9 by Hugh Evans Hugh, I prepared some CAD drawings that I can send to you if they would be helpful. Front and back of the PCB, in dxf format. Jeff

Re: 35s Modification Message #11 Posted by Hugh Evans on 22 Apr 2010, 10:27 p.m., in response to message #10 by Jeff O. Jeff, that would be fantastic. At the very least we can define design constraints from your work. From your experience with assembly/disassembly of the units does my drop-in replacement sound feasible with at least moderate skill?

Re: 35s Modification Message #12 Posted by Jeff O. on 23 Apr 2010, 8:24 a.m., in response to message #11 by Hugh Evans Hugh, I think I have an e-mail address for you, I will look around and send you the files. If I can't find an e-address I will let you know. It was not difficult to disassemble the 35s as documented in my post of a couple years ago. So I would say yes, your drop-in replacement certainly sounds feasible. Good luck. Jeff ...

Re: 35s Modification Message #13 Posted by Reth on 20 Apr 2010, 9:03 p.m., in response to message #1 by Hugh Evans I'm in too. Here is the link Dave is talking about Edited: 20 Apr 2010, 9:09 p.m.

Re: 35s Modification Message #14 Posted by Jeff O. on 21 Apr 2010, 4:09 p.m., in response to message #13 by Reth I'm in. (Obviously?)

Re: 35s Modification Message #15 Posted by Thomas Chrapkiewicz on 21 Apr 2010, 9:01 a.m., in response to message #1 by Hugh Evans On a related note, has anyone developed a schematic of the HP35s? There appear two be two major integrated circuits under the epoxy 'blobs'. I assume these are the processor and a memory chip. Please let me know if there are any details out there. Regards, TomC

Re: 35s Modification Message #16 Posted by Eric Smith on 23 Apr 2010, 2:04 a.m., in response to message #15 by Thomas Chrapkiewicz I don't have a schematic, but what's under there is a GeneralPlus microcontroller (based on a 6502 core) with masked ROM, and a 32KB SRAM. Except as a one-off hack, it's not practical to try to reuse the PCB for anything, as it is much less expensive to make a replacement PCB.

Re: 35s Modification Message #17 Posted by Matthias Wehrli on 21 Apr 2010, 11:28 a.m., in response to message #1 by Hugh Evans Would be interested to but need some pictures first. Matthias

Re: 35s Modification Message #18 Posted by Walter B on 21 Apr 2010, 5:44 p.m., in response to message #17 by Matthias Wehrli Grüezi Matthias, got your site purged?

Re: 35s Modification Message #19 Posted by Matthias Wehrli on 22 Apr 2010, 4:53 p.m., in response to message #18 by Walter B Grüzi as well. Yes, I cleanded it up two days ago. Sorry for teh delay. I got a happy daughter six weeks ago and still have other things to do than collecting things.

Re: 35s Modification Message #20 Posted by Walter B on 22 Apr 2010, 5:33 p.m., in response to message #19 by Matthias Wehrli Congratulations!

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