01.04.2014
The world most famous and in my opinion best handheld computer in the world was and is the HP-41C/CV/CX of Hewlett-Packard. Build and sold in the 80s it has reached "cult status" and a worldwide community of HP-41 enthusiast are keeping the information about it alive.
I can call a HP-41CX my own, which accompanied me during my studies. It was exactly that what a student needed in the 80s, studying electrical engineering. Together with a Math-Module and a card reader at least the electronical support in the exams was perfect.
After several years passed by without touching the device I found out last week that my beloved HP-41CX was "dead" even though powered up with new batteries. Even worse, after I took out the card eader, I noticed that I could spread the upper and lower cover at the upper part of the hp easily.
A clear sign that the problem is real serious. Fortunately there are some very good internet pages available which provide a lot of information and even repair instructions for the one or the other problem.
I decided to document my findings in a "HP-41 repair project" blog; it might be helpful for others, especially with pictures which are easy to post here. Whether my project will be successful at the end remains to be seen.
Keep your fingers crossed.
06.04.2014
Today I checked again the components on the CPU board with the help of the HP-41C/CV/CX Common Board Component Location Diagram and the schematics. Everything was still fine, diodes behave as diodes, resistors showed the right level of resistance and capacitors seem to work as well.
For avoidance of connection problems I cleaned all connectors on the keyboard and CPU board. I once again rasp final tenth of millimeter away of the broken bottom post. GND and BAT + connection from keyboard was ok. So, I pulled my HP-41CX together and the brave companion woke up informing me about:
What a great feeling! I checked about its ON reliability and it looks stable. My assumption is that at first try the connection between the boards was still not good.
The Mathematic Module is recognized.
The Time Module has a problem. Time is flying in the HP-41CX. During 1 normal standard earth minute the time time has come to a value of 2:56' - that's really fast. I need to check what the reason is.
The card reader I checked as well, I inserted a cleaning card and to my disappointment, the cards was sucked in but got stuck in the middle in some kind of glue, that even stick on the card when I pulled it back. The CX was not amused about that kind of input and woke up with Memory Lost. Otherwise still everything is fine. I will now check how to repair the card reader.
Special Thanks goes to Garth, moderator or the hp41.org Forum. He supported me with valuable hints during this porject.