|Re: HP 41C fixes?|
Message #3 Posted by Ellis Easley on 16 May 2003, 12:29 p.m.,
in response to message #1 by Paul Pickett
On the battery contacts, this recent thread mentioned two ways to repair serious corrosion:
I haven't rebuilt a 41 card reader yet but I have done a 97 and a 67 which have a similar mechanism, although I understand the 41 card reader enclosure is a little tricky to open. Actually cleaning the goo was not difficult and you need to get rid of all of it. I used a lot of Q-Tips and 91% isopropyl alcohol. I used silicone rubber tubing to replace the wheel and it was very easy. I found the tubing at an RC model shop, they didn't have the sizes marked, just large and small, so I bought some of both and one was right. The pieces I used are not as concentric as they might be (machines "chug" a little) and since I have several feet of tubing, I'm going to select some more concentric bits some time and put them on.
I wouldn't use 409 on my calculators. I don't know what's in it or other cleaners that are intended to be used without rinsing. I use dishwashing soap solution on a clean sponge squeezed almost dry. For the keyboard, I use a brush with short bristles (~1/2") bigger in area than the calculator (~5" X 4") and load it with just soap suds - just damp with water and a little suds. I hold the brush with bristles up and lower the keyboard onto it and move it in small circles. Then keeping the keyboard facing down (laying it on a towel) I rinse the brush, shake out all the water I can, and use it to rinse the keyboard in a similar manner - I do this two or three times. Then, still holding the keyboard facing down, I use a vacuum cleaner with the small brush attachment (cleaned for the purpose!) to dry the keyboard and remove any water, suds, or loosened crud.