hp48: HELP i'm losing my pixels


i have a problem with the pixels of my hp48gx

at the moment i have lost a line of pixels directly beneath the {HOME} annunciator.

this line of pixels will sometimes flash on then off again

and quite often nearly all the pixels above the stack prompts (4: 3: 2: 1:) are blank (including the {HOME} annunciator.

does anyone * have this happen to their hp48 * have any idea what might be causing it -hp48 bug etc * have any idea how to "undo" this "feature"

thanks in advance




It is most likely that you have a bad electrical contact which causes a row of display pixels to disappear. These kinds of problems are nasty enough to repair even if you don't take into account how difficult it is to disassemble an HP-48 without using dynamite (or without making it look like afterwards as if dynamite had been used)... Sorry.



Hello to all, probably it's not a "scoop" but I found a site where to open the HP-48 could be possible: http://www.contrib.andrew.cmu.edu/~drury/oldhp/how2open.htm However I haven't yet tried with my 48... Greetings!


Hi Paul,

I have two HP48 with this problem. I know three other people with such a problem. Maybe you can try to send you 48 to HP. I think they will exchange the device. Do not ask me about the costs... :-(



Just some musings on the problem.

My son had one of the early Gameboy game systems which were notorious for bad lines of pixels on the LCD. Sure enough, after about six months there were 10 lines out. I discovered that applying pressure to the front of the case would remedy the problem briefly - thus I thus deduced that the solution would be to apply more pressure to the back of the connector on the LCD panel. I disassembled it, cut a narrow strip of double sticky foam tape and placed it over the elastomeric connector on the LCD to increase the pressure on the contacts. I then reassembled the case and turned it on. It worked perfectly for about 5 minutes and then one or two of the LCD columns would fade out intermittently.

I attributed this to the stiffness of the flexible ribbon connector and thought that heating the Gamboy to approximately 130°F would soften the plastic ribbon and allow more intimate contact with the LCD panel. I turned the oven to low and allowed it to preheat, placed the Gameboy on an insulated cookie sheet and waited for the oven. As I waited, I envisioned my son holding a 10” x 18” ¼” sheet of plastic in his hands and crying – not a pretty picture.

I decided to try a less extreme method of incinerating my son’s Gameboy and placed it in my car parked in the sun for several hours while making sure the game was not in direct sunlight. That solved the problem and the system has worked perfectly for the last 9 years.

I realize the difficulty of disassembling an HP-48 but leaving it in a car for a few hours may solve your problem. Here are a few caveats before you do this:

1. Remove any plug in cards – less risk.

2. Start in the morning with the car cool and leave the calculator in its case to provide insulation which will limit the rate of temperature change.

3. The manual states that the storage limit for the HP-48GX is 149°F but does not mention if this is with or without batteries – I would remove them if it were my calculator.

4. Do this at your own risk!


many thanks for your prompt replies all

its interesting that heat may be the "fix" Bruce as we use the hp48 in the field (i'm a survey technician) 5 days out of 7. And our summers get pretty warm here in Aussieland.

a few times i have left it on the dashboard and the screen has turned black. it is winter here now (and darn cold some mornings) so it may "right" itself come summer.

I think the "gameboy on the cookie sheet" was great. (who says men never bake) thanks again

thanks Vicktor for your response. BTW i have taken a broken hp48g apart to see whats inside (and yes its pretty tough work) i used an article "how to take the Hp48 apart" but i think it was a HP48SX as many of the rivets were not in the positions shown.

thankyou Andreas sending it to HP is quite likely the route i will take (i'm in surveying not engineering)

bye for now


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