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Bad HP-48SX ON/ATTN key - Printable Version

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Bad HP-48SX ON/ATTN key - Al Kimball - 10-28-2003


The ON, or ATTN key on my 1991 vintage HP-48SX is not working well when it comes to turning on the calculator; however once the unit comes to life, I can press ATTN at will and the button works every time.

Some days (but rarely) I push the button and the calculator springs to life right away; most days I have to press and hold the button for several minutes before it starts working. Sometimes I find that grabbing the unit with both hands and giving it a gentle twist (yikes!) will do the trick, but I really hate doing this.

When it does start to work, I see the little hour-glass very briefly and if I let go of the ON key while the hour glass is present, the calculator comes to life.

I thought it might be the batteries or battery contacts, but I've beat that horse to death... It's not batteries.

It's almost as though there was some weird capacitive based startup feature for the calculator that isn't working, because once the unit comes to life, all keys work (including the ON/ATTN key) and the unit is fine otherwise.

From another post (posted in Oct/2003, last month), I tried pressing just above the B and C keys on the raised portion below the display to see if it was the internal keyboard connector... to no avail.

Any other suggestions?




I currently have three HP calculators, an HP-41CX with many modules/BC reader (use it all the time), this HP-48SX (used less and less cause it won't start), and a newer HP-12C Platinum (horrible reading the yellow graphics on the shiny silver face plate) which I bought just because I wanted it.
Sure wish I had spent the money on that HP-16C in college; it's one of only 3 things I really regret not buying in life. :( Thanks again for any help on the 48SX. :)