Dusting and Dustproofing
HP49g+ & HP50g Displays


by Joe Horn

Ever get annoyed by dust that's stuck behind the "dust screen" of your expensive HP calculator? Well, don't get mad; get it out! There's a quick and easy way to remove the dust from the displays of HP49g+ and HP50g calculators. If done as shown, it won't even void the warranty.

As a bonus, an optional "dustproofing" technique is included as "Step 3.5" of this article. It renders your dear HP calculator absolutely immune to dust in the future, without ANY visible modification!

Everything in this article applies equally to the HP49g+ and HP50g calculator models.


STEP 0: Your Workbench

All that you'll need for the dust-removal procedure is shown in this photograph:


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Shown from left, clockwise, are:

  1. Your HP calculator. Obviously. Well, actually, MY calculator is shown, but ... you know what I mean.
  2. Suction cup. This one was surgically removed from a stuffed Garfield, and then a keychain was added to improve its yankability. Anything that'll stick to the dust screen and can be yanked on with blissful abandon is ok.
  3. Blower brush. The kind used for camera lenses is great, but anything will do, as long as it removes more dust than it deposits.
  4. Flashlight, preferably a very bright one. Shown here is a 3-watt LED, but anything'll do.
  5. Optional: adhesive bandage. Useful if you're a total clutz who cannot use a suction cup without causing bodily injury to self and bystanders. Warning: If there ARE any bystanders, procure additional bandages. And safety goggles. For them.


STEP 1: Attach

Press the suction cup to the dust screen firmly enough to get it stuck, but not so firmly that you bend it down into the LCD and crack it. To avoid that horrifying possibility (yes, it IS a possibility), position the suction cup not smack in the middle but closer to a corner, such as shown here:


Click Picture For A Pointlessly Larger Version


STEP 2: Yank!

Holding the calculator firmly, yank the suction cup with the suddenness and assuredness of a karate master breaking bricks, all at once... POP! and the dust screen will look like this:


Click Picture For A Pointlessly Larger Version


STEP 3: Clean

To really get your money's worth out of this enterprise, look at your calculator's LCD at an angle, illuminated by your flashlight at various angles. You'll see something truly nightmarish like this:


Click Picture For A Pointlessly Larger Version

We have met the enemy, and it is DUST! Before continuing, heap upon it all of your pent-up scorn and other useless negative energies. Then sweep it all away with your blower brush, or airgun, or whatever weapon of dustruction you prefer.

WARNING: Dust the inside of the dust cover too! Before replacing it, BE SURE to use the flashlight (at an angle!) to verify that there is NO DUST (or fingerprints!) on either the LCD or inside of the dust cover.

NB: If you do not wish to DUSTPROOF your HP calculator, so that it'll REMAIN dustfree, skip ahead to Step 4.


OPTIONAL STEP 3.5: Dustproofing

Warning: The following procedure voids the warranty of your HP calculator, so only do it after the warranty expires (or if you don't care about the warranty).

HP actually went to great lengths to make sure that the HP49g+ and HP50g don't get any dust stuck under their dust screens. The dust screen is sealed against the calculator frame, as is the LCD. They thought of everything. Trouble is, somebody somewhere messed everything up when they noticed that the HP logo appliqué is made out of aluminum. They had a cow, and insisted that any metal on the outside of the case can cause electrostatic something-or-other, and an AIR PATH between the logo and the innards of the calculator had to be added to the design. Amazingly, that's what happened. Look at this:


Click Picture For A Pointlessly Larger Version

The aluminum HP logo sits atop a very short plastic pillar, as you can see. That pillar has a hole that runs all the way from its right side (very visible in the photo above) down to the inside of the calculator. Unfortunately, the logo also pokes through a hole in the dust screen. There is no hermetic seal between that hole and the hole in the logo pillar. And there's a direct dust path from THAT hole to the air between the dust screen and the LCD! This is clearly a case of excellent HP engineering being messed up by forces beyond their control... and possibly even beyond their knowledge.

Therefore, all you have to do to make your HP calculator absolutely dustproof is PLUG THAT DUST PATH. You can either plug the electrostatic air duct in the logo pillar (not recommended, since I have NO IDEA what that's all about anyhow), OR you can seal the gap between the HP logo and the dust screen's logo hole. If done on the inside, before replacing the dust cover, it will be a completely invisible modification... but it will void the warranty.

If you don't mind slightly uglifying your expensive HP calculator, you can get the same effect, without voiding the warranty, by simply placing a piece of clear adhesive tape over the HP logo hole in the dust cover, thus sealing the dust path right at the source. It works, but looks a little geeky. If that doesn't bother you, or even sounds like it might be helpful for your social life, then go for it!


STEP 4: Replace

Replace the dust cover and press down firmly all around its edge, to re-bond it to the traces of glue and adhesive tape that held it orginally. The result is a 100% dust-free display! Yay!