From: "G. Scott Marlowe" Newsgroups: comp.sys.hp48 Subject: Openhp.doc Date: Sun, 11 Feb 1996 13:35:03 -0700 Organization: University of Colorado at Denver Lines: 147 Message-ID: NNTP-Posting-Host: ouray.cudenver.edu Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Title: Openhp.doc Author: G. Scott Marlowe, Date: 11 February 1996 Version: 0.90a OPENHP.DOC A file describing how to open the HP48 series calculators. History: When I opened my HP48G, I did so by removing the tin overlay and had a heck of a time with a rolling pin getting it straight. Someone sent me a text file on how to open it from the back. Lately, I had to replace my older calculator when my keyboard finally quit working and I tried this method on my new HP48G. It works fine. At least for me. *** OPENING the Calculator *** Overview: The openeing of the HP calculator will consist of several logical steps in order, they are, in general: 1: Remove battery cover and batteries. 2: Remove IR cover. 3: Cut rivets near IR/serial ports. 4: Remove Rubber feet/contacts from battery bay. 5: Cut or drill rivets in battery bay. 6: Pop back cover off of calculator. 7: Disconnect + terminal from it's boss. 8: Remove back cover completely. *** In specific *** It goes something like this: 1: Pull your battery cover and batteries. 2: Remove the IR cover (takes a bit of effort on a G, but it comes off using your fingernails, just a micro-newton before your fingernails come off your fingers...) For the following, see Figure 1. (FIG1.GIF) 3: Using a heated, sharp exacto knife, cut through the plastic just outside the IR pair, and just outside the serial port. I use a stove set on high to heat the blade of mine, but be careful of the hot handle! Use an oven mit to hold it. Warning, inaccurate ascii art follows: --------------------------------- | |XXXX--------------XXXX|/____|______Cut side to side, as near to the top | | [....] [O O] |\ | of the calc as you can while staying | |----------------------| | within the serial/IR area. | |______________________| | \_______________________________/ ^ ^ |----------------------| Sides of the area covered by the red IR cover ^^^ ^^^ SER IR There are two rivets behind each XXXX, and they are paired close together. *********************************************** >From the other end, (the end with the batteries.): See Figure 2. (fig2.gif) 4: First, you'll need to pull the little black rubber feet with the oblong contacts that make the batteries connect end to end in the battery compartment. Best way I've found is: Place your HP, battery bay open, on a heat register, with the air blowing into the battery compartment. After 5 minutes, pull it off, and using a pair of small jeweler's screwdrivers, carefully peal the contacts, rubber feet, glue and all, from the HP. You should have a little black and silver thingy, all in one piece, when your done. Now do the other one. Note that even fairly heavily damaged ones can be re-built pretty well, but mine came off with virtually no damage at all, and the batteries will work as a great aid to pressing them back into place later. 5: Cut/drill battery bay rivets. Top of calc ^^^^ _X_____________________X_ Hole in --->|[ ] | battery |[ ] | holder |-------------------------| <--- | | |--- Ridges between batteries |-X-------X------X------X-| <--- | [ ]| |______________________[_]| The X's mark where the rivets on the bottom are. The two outside bottom rivets are right under the middle of the now removed black rubber contact thingamabobs. the two between them are equally spaced out between them. They are just towards the front end of the calculator. the two Xs nearer the front are best cut as close to the top (keyboard side) of the calculator as possible, and are lined up with the two outside Xs at the bottom. Cut the four near the bottom first. Use a heated, sharp exacto to cut through these rivets as well. For the following, see figures 3 and 4, (FIG3.GIF and FIG4.GIF) 6: Using a 1" putty knife, pop the back cover loose, starting near the front end of the calculator. There are three snaps on each side, one set on either side of the A-F row, the next on either side of the fourth row, and a final set near the bottom row. Starting near the top, insert the flat edge in and up under the top of the top case, about 1 key row's width up from the top row. Rotating the handle up, you should be able to force the bottom of the case out and away. This will open this snap. Do the other side the same way. You'll need to hold the case apart a little with either toothpicks or your hand. Moving down, do the second set of snaps, then the last ones. The last ones are the hardest to open. Once these are all loose... 7: Snap the + terminal off of its plastic support boss by inserting a small jeweller's screwdriver behind it and popping it free. 8: Rotate the back shell away from the front, until the bottom middle snap pops off. You may have to apply a sideways rotational force to get it to come loose. If you plan on opening and closing your calculator a lot, bend in the two metal snaps near the bottom just a little so they are easier to pry off. Be careful not to defeat them completely though, since they help hold the calculator together. Final warning: I HAVE tried this. It works well, but if I didn't have my older 48G as a guide, I wouldn't have felt nearly as confident as I did doing it. Note that the plastic of the 48G is fairly soft, and a small drill run by hand would work very well for the lower four rivets shown above. Someone who tries this should really report back on how it works...