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HP 48 SX unresponsive - Printable Version

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HP 48 SX unresponsive - Bob Purdie - 01-15-2007

I picked up an HP 48SX that is in cosmetically perfect condition, but when I put a set of batteries in it, it refused to turn on. Iv'e tried the soft resets and the hard reset via the reset hole under the foot, cleaned the battery terminals with an eraser even though they didn't appear to have any issues, but still no luck. Does anyone have any other ideas I can try before trying to open the case?

Re: HP 48 SX unresponsive - Allen - 01-15-2007

For as much trouble as it is to open the case without doing more damage, I recommend the following:

1. try adjusting the contrast to make SURE it is dead.

2. Press on the keypad just above the C key while you turn it on.

3. Repeat step 2 for six other keys ( O,Y,A, F, 7, 9)

4. Sell it for parts and use the capital to buy another.

On many models other than the 48sx #4 would be a last resort, but unless you are unemployed or bored (or both, SMILE) , it is probably not worth your time to repair it when they can be had on TAS (that auction site) for $60 to $120 in working condition, while $20 to $35 for parts.

Otherwise, I have several 48g calculators with this condition. Using a DC powersupply and ammeter I can determine that the calculator is ON and responds to keypresses, but the display is bad. You can tell based on the current draw in different modes. The processor draws much more current when servicing interrupts (such as keypress, running programs, RAM access and IO) than when only powering the LCD and clock.

Edited: 15 Jan 2007, 3:45 p.m.

Re: HP 48 SX unresponsive - Bob Purdie - 01-15-2007

Yahoo! it was a number 2!! The bad news is it seems to need the pressure over the C key for the keyboard to work properly after it is turned. But hey it's better than nothing at all. Maybe I can figure out a way to make the keys respond all the time now.

Thanks for your help!

Re: HP 48 SX unresponsive - Bob Purdie - 01-15-2007

I've played with it a bit more now that it powers on and it seems that most of the keys are working fine except for the "ON", "B" "C" and "F" keys. I'm beginning to think that something may have been spilled on it. Anybody have a suggestion to fix that issue? And by the way to Allen your sugestion that I am either bored or unemployed, Yes to both.