|Re: Keys failing on 32S|
Message #4 Posted by Dallas Osborne on 2 July 2008, 1:45 p.m.,
in response to message #3 by Randy Sloyer
Keyboards of this series are the weak links. Normally, once they are gone, you can keep the LCD (and main board if you like) for other units that may break.
That said, if you are really ambitious and fairly MacGyver-ish, you can try this: (and, yes, I have done this…once…and it was a real pain. But it bought my 42s another 14 months of life before I had to throw myself at the mercy of the eBay shark).
(For really great images of the guts, check out Takayuki’s page:
Down at the very bottom of this page is a shot of the heavily heatstaked keyboard sandwich.
And you should check out Paul Bogger’s excellent description of the guts:
I have used this article to great extent while I conducted the replacement of my 42s’ LCD from a nasty old 17bII and the swap of the keyboard from a 32s with a cracked LCD to the same 42s.
First off, if the keys do not pop back up, you need to replace the entire keyboard. Or, if the keys have the normal snappy click, the contacts, as mentioned by others, may be dirt or may have been forced away from the contact board by excessive pressure.
If they are dirty, I would recommend using gentle pressure with a very, very soft brush on the carbon button and Q-tip the contact point with a very clean drying solvent such as 100% alcohol or the cleaner you would use to clean flux after soldering.
Here we go:
-(For a keyboard replacement) Obtain a ‘for parts’ pioneer with a fully functioning keyboard.
-Open the calculator using the standard method and pull the main board. (I used popsicle sticks (and not metal pry objects) to carefully pry the sides apart; it was a lot easier on the fingers.)
-Carefully put a small hole in the center of each of the heatstakes in the keyboard sandwich 3mm deep. (Use a drill press and a 1.5mm bit.)
-Next, take a very small sharp chisel and make two cuts, 180 degrees from each other, into the heat stakes.
-Now, you will need to carefully squeeze the heatstake. I used the chisel blade from an X-acto woodcarving set and a fine set of needle nosed pliers to work the previously melted sides up. Free the board, one stake at a time, and starting from a lower corner and working in a logical manner from bottom to top.
-Be careful not to damage the ribbon at the top as you pull the sandwich up and lay it over the LCD.
-Do what you need to do; replace or clean the thing.
-Once that is done, you need to prepare the heatstakes and backplate for the eventual gluing. Use a small pair of needle nosed pliers to ‘roll’ the heatstake plastic up again so the board will fit smoothly over them.
-Take a medium grid sandpaper and rough back surface of the backplate around each hole lightly. Wipe it clean with a cloth and DON’T do any of this over the other bits of the keyboard. Clean it with Acetone or lacquer thinner. (Don’t use alcohol or anything that could leave a pertroleum residue.)
-Reassemble the sandwich, get everything lined up, and seat it back home.
-Use a small flat chisel and give each heatstake a little twist in the slot you made earlier. You are just trying to put a little pressure against the backplate holes. Now take a metal punch and alternate between rolling the pointy end around in the heatstake hole and using the backside to gently mash the plastic down flat. It doesn’t need to be perfectly flat against the backplate.
-Take a small screw - it should fit without force yet cut a small threat into the heatstake. (Or use a tap, if you have one on hand). This prepares the inside of the heatstake with a surface for resin to hold on to.
-You need to now build a grid that will apply pressure to the areas of the backplate between the heatstakes evenly. You will be placing a moderate weight to this grid as the resin cures. (I used 14, slightly shorter than 7cm, balsa wood sticks for model building and placed them, two each, horizontally between the row of heatstakes.)
-Similar to the grid for the back, we need to prepare a set of stand-offs that will keep the keys from mashing against the surface of a desk or table when we weight down the back grid. Use about ten of these and place them horizontally between the keys of the calculator and on both sides of the LCD (two above the LCD).
-Mix up a very strong epoxy solution. I used J-B Weld, it is rather strong once cured and will remain pliable for hours. This will allow you take your time. Place a small glob into the hole in heatstakes and push it in with a toothpick. Place a slightly larger glob over the whole heatstake. Use the toothpick to work this between the plate and the formerly melted edges. Create a nice low mount over the heatstake and onto the roughed area of the backplate.
-Set the calculator face down and set up the grid on the front and back. Place a couple of chubby books on this. You are trying to create good pressure but not kill the thing. I used an old o-chem book.
-Don’t mess with it for a day and half to two days. I am serious about that! Leave it alone.
Last word: Assume the calculator is dead before you embark on this project and you will either be pleasantly surprised or able to shrug your shoulders at a good attempt. I also recommend taking pictures along the way. I really wish I had done that…really wish I had done that.
You will be a hero to many pioneer owners if you can document this with photography.
EDIT: I agree with Randy about spraying contact cleaner into the keyboard. The only place I would ever use solvent is directly the actual contact board side, NOT the carbon button pads that the key posts strike.
Edited: 2 July 2008, 2:28 p.m.