woodhams@phoenix.Princeton.EDU (Michael Woodhams) (05/10/91)
I have an HP21 and an HP25 which do not work (part of a collection of old HP's.) The reason for the HP21 not working would seem to be a battery pack that has leaked, as it was covered in white crystals. I suspect the crystals have permeated the entire calculator, as the "4" key will not depress, presumably due to being jammed by xtals. I am considering soaking the calculator in water and rinsing it a few times, letting it dry thoroughly and then seeing if it works, but this seems a very extreme method. (I've already checked that the xtals are water-soluble.) Does anyone know how to open up these calculators? Does anyone have a less drastic solution? (pun unintentional, but appreciated.) Does anyone have any old HP's they want to sell me? Michael W. P.S. Useful note to other HP collectors out there: Whenever you post to a newsgroup, put in a P.S. asking if anyone has old HPs they want to sell you. This has been successful enough for me that I am
conte@crest.crhc.uiuc.edu (Tom Conte) (05/10/91)
In article <9361@idunno.Princeton.EDU>, woodhams@phoenix.Princeton.EDU (Michael Woodhams) writes: > > Does anyone know how to open up these calculators? This is only a partial solution, sorry, but... To open up a woodstock-series calculator: Turn the calculator over. Have a #0 phillips handy Use a pin to remove the two lower rubber feet (they are not glewed in, so you can pry them out). This will reveal two black screws. Remove The screws. Slide the back *up* relative to the front. (There is a J-style hook between the front and the back at the base of the keyboard). The two parts should come off revealing: One printed circuit board connected to the calculator's keyboard by a line of spring-clip pins. The battery contacts are round soldered-on disks that extend from the PC board. I've found that in mine the solder connection to these disks sometimes gets a fine hairline crack in it. Re-soldering the connection might fix some of your problems. ------ Tom Conte Center for Reliable and High-Performance Computing conte@uiuc.edu University of Illinois, Urbana-Champaign, Illinois Fast cars, fast women, fast computers