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WP34s Repurposing Journey PhotoJournal
01-27-2015, 09:36 AM
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WP34s Repurposing Journey PhotoJournal
The purpose for posting tonight is to start a photo-journal of sorts documenting my repurposing experience converting the HP30b business calc to the now famous WP34s community scientific programmable calc. My hope is to encourage other first-time repurposing DIY folks like me, let folks know the kinds of things I ran into, and to share ideas (materials, parts, construction techniques, &c. For most folks these days the main issues are going to be 1) flash cable, 2) main board pcb mods (crystal, caps), and 3) pc systems issues.

I have opted to mod the calc (crystal and caps), and I will also be constructing my own flash cable box, flash clip, and IR mods. I am not going to be repeating the on-line doc other than to make clarifications where I think the doc could be clearer, or where I think other noobs like me would find it helpful. I have most of the materials I'm going to need including the HP30b(s) (man was that a lot of research and cross checking) but some of it has not arrived yet. I have started construction on the cable box and flash clip.

[Image: materials.png]

I made my flash clip (Katie clips included) using pogo stick (compressed spring header pins) mounted in modeling wood (bass wood) with the comm cable soldered directly to the pogo pins. The Katie Clips are soft aluminum sheet, and the construction is wood glue and tape (keep it simple, keep the cost down).

[Image: pogopin.png]

I got my pogo pins from Sparkfun for about $0.95 per pin. There are different kinds of heads... I chose the bullet shaped pointed pin for better alignment and better electrical contact. I am new to working with these pins. If you use flux they solder well. The pin is a compressed spring (pogo stick) tube which is used in this project to connect to the gold pads on the 30b pcb through the back cover (for connecting the unit to the PC to download the WP34s flash image. There are six tiny holes through the back cover (I'm leaving mine, discussed later) and so I'll be using six pins. I purchased a couple of extra in case I screw up one or two.

[Image: backplate.png]

I am leaving the tiny holes in my unit. This is easier, and will help to align the pins during flash without the possibility of shorting. i ran into a problem, however, with this approach; easily solved with a jewels rasp (tiny engraving tip for Dremel tool). HP tries to make sure that their flash cable does not get plugged in backwards (the female backplate is keyed, the clip slots are different widths, and three of the tiny holes in the backplate are smaller. I used a very fine, tiny, jewelers rasp (engraving tip) in my fingures (by hand, no motors!) to make the holes all the same size (just a flea eyebrow hair larger than the pointed heads on the pogo pins. I used the same rasp for making the very snug holes in the bass wood to hold the pogo pins in place. The pins I'm using are 33mm in length (1.3 ") so it is important to have aligning holes holding the pins at the top, and aligning holes holding the pins at the bottom (we want NO shorts).

[Image: flashclip.png]

I also made a 'keeper' (not shown) that is simply a small bass wood block with six holes milled into it to 'keep' the pins aligned, straight, and clean when not in use. My Katie Clips are designed for 3mm of compression when the clip is plugged in. The tension needs to be firm to prevent noise in the comm line, but not sooo firm that the clips pop out! I had a little trouble with this, so getting the clip at the right angle, and getting the compression tension correct were somewhat of a challenge for me. (I have been told that some people just hold the pins down with one finger during the flash; with the pointed pins probably would work). I plan to keep my hands free messing with the PC, and for better control over noise in the comm connection.

Soldering to the pins was easy (use flux, its our friend) and I used an old disk drive ribbon cable for the comm line (just trimmed it up with a pen knife). The wiring is arbitrary but I did take care to diagram in my notebook the wiring from the colored wire out the J connector labels (and meaning) to make things easier when I get the cable box and power supply finished.

PS The trick to mounting the pins in the balsa (or basswood) block is to make the holes manually with a jewelers rasp checking frequently for 'straight' and 'firm'. The pins need to be absolutely straight AND the tips need to be 2mm apart (almost no variation will work) at rest in order for the pins to line up with the tiny holes through the backplate. I'll be honest, this took me most of the evening to accomplish (I do not have a dremel press).

PSS While I'm working on the cable box I'm also spending some time in the WP34s manual (with the mac 34s emulator) learning the ropes)... its an exciting little unit.


Kind regards,
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WP34s Repurposing Journey PhotoJournal - MarkHaysHarris777 - 01-27-2015 09:36 AM

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