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Full Version: It's alive, the franken41
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Very ugly in it's beauty, and back from the dead

A TAS 41C that was sooo much worse than words described; vivisection revealed a halfnut with all posts broken, half the back screws missing (no posts to screw into), one screw having penetrated the front (long screw in short hole), heavy corrosion on the flex connector and the flex connector block superglued in place as the back screw pads were broken for the top screws, no side/battery/port covers, trim bezel fubar, no rubber pads over the screw holes.

Really little more then then a display, motherboard, and keyboard; barely clinging to life and on the organ donor list.

The revival took several hours using epoxy putty, o-rings, and superglue. Replaced flex connector (shout out to Diego!), trim bezel, screws, rubber pads, rebuilt front and back case, 3-D printed all covers. The spark of life provided by a 3-D printed battery housing a LiPO battery with a 5V boost circuit (the prototype works).

Now to see how well it rampages!
Hey, congratulations, throw some pictures for us!
The HP-41CV is still alive and well, passing all diagnostic tests. I will try to upload some pics soon.

My real hope was for the power pack. a LiPo battery using a charge/boost adapter (SparkFun Power Cell, PRT-11231) that fit well within a 3D printed housing. The power supply works well for 3-4 days with a 400mAh-500mAh battery but the no-load current on the boost circuit is just too high and quickly depletes the battery to the low voltage protection point. I have been comparing load with larger LiPO batteries, NiMH, and NiCad batteries and it is the boost circuit that is depleting too quickly.

Maybe I can use a solar cell mounted on the battery housing, I can then just flip over the calculator when not in use to keep the batteries charged.

So far the best power solutions I am finding for the 41C's are using the standard battery housing (OEM or 3D printed) with either NiNM N-cells (with a 3D printed AA:N adapter for recharging the cells) or standard N-cell alkali batteries, and rebuilt NiCad pack using 1/3AAA cells.
I am also working for a better battery solution. My mini boosters needs uAmps in idle state.

Two problems remain to be solved:
1. The power requirement with the card reader (250mA) needs 3xAAA, but there is not engough space. I ordred a bigger DC-DC booster for my next tests.
2. The undervoltage protection won't work with Battery flag. I'm working for a HW solution.

Best regards from Basel
Hans Peter
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