Panamatik’s Woodstock Low Power is an Incredible Product

[Maximilian Hohmann]

Hello!

I can report a partial success with LP kit number 0008. My donor is an HP-22, Serial Number: 1605S16186.

It took me much more time than expected to desolder the anode and cathode driver chips without causing damage. Initially I tried with my old mechanical desoldering pump but it's opening has grown too large over the years for precise work. Then I tried the desoldering wick provided with the kit but without much success. Next I tried my luck with desoldering needles which I had arrived from China in the meantime. They are very good for removing parts from single sided PCBs and also parts with two or three leads (like that capacitor and the potentiometer under the display) but can't desolder integrated circuits from double sided PCBs.

Desoldering needles are hollow stainless steel needles (basically hypodermic needles) in plastic holders which you push over the component lead with one hand while melting the solder with the other hand. Like this you separate the lead from the PCB contact and it can be pulled out clean. A set with 8 different diameter ones costs less than 2 Euros including shipping from China:


After that I ordered the next cheapest desoldering tool, a mechanical pump with a heated tip. They can be found for example from the well known Belgian electronics retailer Velleman or from various eBay sellers. Mine cost less than 10 Euros including shipping and arrived within two days:


This tools, despite it's ridiculous low cost, works miracles. The two chips were out of the PCB without damage in less than 5 minutes. The best 10-Euro-investment in a long time! Maybe a tool like that should be supplied with every LP or ACT kit (just an idea)?

But now comes the point where I am a bit lost. I cut all traces as required and soldered all pieces into place as described in the manual. At this time I left away all the optionals (IR diode, buzzer, GPS, on-off-switch) for a basic function test. Connecting the board to a laboratory supply set at 2,4V (= 2x NiCd cell) I got instant success :-) The display lights up with it's welcome message, albeit very dim (maybe 2,4V is just a bit low?). But all the keys are off by one column (e.g. pressing "4" produces a "5", some don't seem to do anything at all) and the On-Off switch behaves like "Prgm-Run". So either I made a mistake or the HP-22 board is somehow different?

Before I damage anything I will rather wait for advice!

Regards
Max

NB: Just took another picture of how the 6-pin connector with the red end soldered to ACT pin 4 looks like in an HP-22: