|Re: HP49G repairs - how to open|
Message #4 Posted by Randy Sloyer on 13 Sept 2003, 8:23 p.m.,
in response to message #3 by Mark Ordal
Using a 5/32"/#22/4mm drill bit, drill the tops off the six heat stakes in the battery compartment. Do not use a power drill, but simply twist the bit in your fingers. You'll find the blue plastic drills quite easily by hand. You only have to go deep enough so that the rivet releases, you'll end up with a blue ring when you've drilled far enough.
Now find yourself a clean, dry wooden popsicle stick. Seems silly as everything handy is made of metal but the wood will not mar the plastic case. From the bottom, slide the stick up the channel that the cover fits in about a half-inch. Use the stick as a crowbar and separate the case halves. Repeat on the other side. They will pop open with enough force.
Once both halves are free at the bottom, pulling away from the case, free the positive battery clip from it's retainer.
Hold the case bottom in one hand, the top in the other and pull the halves apart. Don't seperate by more than a quarter of an inch or so or you'll break the case.
Now, push the bottom half up toward the top of the front half. The halves should separate and the top should slide up and free itself. You should not have to pry or do anything other than push up and pull apart at the same time. Once it pops apart, you may trash the battery clip, but it does not matter, it is easily bent back into its original position.
The next step is to separate the logic board from the keyboard. Above and below the three large chips at the top you'll see six twist tabs, three above, three below. Study them carefully. Normally, you will have to twist the bottom tabs clockwise, the top counter or anti-clockwise to release. In some machines the direction stated is not correct and you will need to establish the proper direction to free the logic board. You do not want to twist them in the wrong direction as doing so will surely fracture them and you will be cursing the dyslectic person that assembled the unit. Once the tabs are centered, you can lift the logic board up from the bottom and free it from the six cinch points.
It's now time to inspect the keyboard connector, especially on the far left side as the last connection to the left is the right most row that you are having trouble with. Bend the white plastic of the keyboard connector upward and see if the foam pad underneath is centered in the case. Many times it is not and it causes the loss in connection. The solvent UN-DO (aka heptane) available in hardware stores and Wal-Mart will cause the sticky pad to release so that you can remove and re-position the pad in the proper place. Many times you'll only need to bend the keyboard connector upward to reestablish proper connection. Clean the keyboard and logic board connections with a cotton swab and isopropyl alcohol. Reassemble, twisting the tabs in the reverse of the direction as required to remove. You'll get about four to six cycles on these before they fracture so be very carefull as to not to waste close/open cycle for no good reason. It is best to start with the left and rightmost bottom tabs followed by the center bottom then the left/ right upper and finally the center upper. This is the best order to center the logic board to insure the proper connectiion to the very fine pitch LCD connections.
Once back together, simply snap the black bottom back into place. Install batteries and test. If all goes well, your 49G will be back to normal.
Edited: 13 Sept 2003, 8:25 p.m.