|Re: Cleaning an Hp41C|
Message #2 Posted by Andreas Terzis on 16 Mar 2006, 7:32 p.m.,
in response to message #1 by Xavier LaRue
I have had the same problems in the last couple of months with machines I bought from 'crooks' on eBay (sorry friends - it's the most polite word I can use). In fact I recently bought a 'MINT' HP-41CX only to find it had tons of scratches on the sides, matte (non-shiny) keys probably from overcleaning, and the 'clean without corrosion' battery contacts to be FULL of corrosion!!!
In any event, I have read posts from before where people used 409 cleaner on the keyboard. You can open the machine by taking the four pads on the bottom off and unscrewing the four screws. There are some posts lately to me, suggesting to be very careful with HP-41C and HP-41CV machines, where HP-41CX machines are easier. The colleagues were suggesting to be careful with the former ones as the boards internally need some pressure to stay together. In fact, later machines that were Halfnuts (even HP-41CVs) would not be difficult to open. (Halfnuts are the ones with the rounded edges on the display - you probably don't have one of those).
Once you open the machine you can use distilled water and a Q-tip to clean the circuit boards inside. I would use some 'Dust Off' myself as well. That is the can that has some kind of condensed chemicals (difluoroethane). As far as cleaning the battery contacts, there was some discussion recently that one could use lemon juice or vinegar, and coat them with butter from what I understand. I just used lemon juice and a Q-tip and it cleaned most of the base deposits on the battery contacts of my machines (about 90%). I think the relevant post was called: 'Battery leakage and cleaning' but for some reason I cannot seem to access it, maybe due to the passworded changes to the site that were implemented lately by Dave Hicks; he can comment if that's the case.
I hope that helps a little bit.