HP41 / SY41CL Mini-B USB Power Connector (Module) Message #1 Posted by Matt Kernal on 7 July 2012, 12:42 a.m.
Inspired by Kerem, and Diego, and Frido (OK, Yes, I COPIED Diego and Frido's ideas! ;-), I used a Mini-B (5-pin) USB adapter and a 41 memory module housing to make a USB power connection/module for my 41CL today. Although it doesn't save a port like Kerem's solution, I wanted to have a "portable" means of powering up some other 41s I have around (since I regularly find myself without N-cell batteries when I need them).
Disclaimer: First of all: My photography skills are horrible - I'll never pretend be a Dave Hicks or Geoff Quickfall. Second: This sequence of photos and information is purely for entertainment purposes. If you (foolishly?) attempt to replicate the details below on your calculator (note: some details were purposely left vague), I will not be held responsible if anything detrimental happens to your property. All the pinout information for this project is freely available on the web. (Besides, I Cannot be held responsible, as I have no money - I have a family instead! :-).
[Fig.1] Because I would be experimenting (and because they were inexpensive), I bought two different styles of USB adapters from an <awesome!> local cable store. One Mini-B socket had a "shroud" (left) and the other one didn't (right). I ended up destroying the left one (learning experience), so the right one was used for my connector, but I also used the shroud piece from the left adapter:
[Fig.2] First I took the 41 memory module apart. I used solder-wick to unsold the memory chip from the solder-pads. I *thought* I would be using the perf-board but didn't need it after all (once I discovered that I would be able to use the wires inside the USB adapters).
[Fig.3] This is the "guts" of the adapter that later got destroyed. The pic serves to show that the black outside plastic (actually rubber) adapter housing can simply be sliced length-wise and removed. The white/clear center area between the USB connectors is fairly soft - I think it's just hot-glue-gun glue. I saved the black shroud at the Mini-B end and nothing else.
[Fig.4] Once I cut away enough material from the second USB adapter ([Fig.1] right side), I was able to access the individual wires. I plugged in a USB power supply and located the "+5V" and "gnd" signals. They are the extreme "outside" pins on the Mini-B connector. I then cut the three unused wires flush where they came out of the clear material.
[Fig.5] This pic shows the Mini-B connector wires soldered to the (former) memory module solder pads (per Diego's and Frido's links above). The right side of the pic shows that the bottom-half of the housing has been "notched" to accept the USB connector.
[Fig.6] Parts placed back into lower half of memory module housing. The shroud will cover the "exposed" metal bits (as our UK friends would say ;-) on the Mini-B. Almost done.
[Fig.7] You have to test it again, right? Note: Paper plates come in handy so you don't scratch wifey's table.
[Fig.8] New USB power module plugged into the 41CL. Before taking this photo, I first turned on the 41CL and started the clock, then plugged in the USB power supply (no smoke!), then removed the 4 N-cell batteries and the clock remained running (hard to see in pic). Yeah!
I haven't glued the module housing back to together yet. Should I use the Polystyrene cement that Randy strongly recommends, or is there something more forgiving, like rubber cement, in case I need to get back into the housing? Note: The original factory "bond" was only at the interface of the top and bottom housing halves (no clip retainers used in here).
Thanks again guys for the inspiration. I would be remiss if I didn't tell Monte THANK YOU for his great contribution in his spectacular 41CL board!.
Matt
Edited: 7 July 2012, 2:32 a.m.
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