HP48's with Batteries Left Inside (will not turn on)

[shoman24v]

Just curious, is there any way to bring back an HP calculator that had batteries left it them for two long? I have 2 that won't turn on. One was new with the batteries never taken out, one like new. Barely any corrosion. Sanding the connections and pressing the area above the keys does not do anything.

Has anyone had success bring them back? If so, what did you do? Or are they dead?

[EugeneNine]

Its probably the rubber that presses the connections together. Press below the screen while trying to turn on, the rubber rots away and doesn't press the connection tight.

[shoman24v]

(02-02-2023 04:29 PM)EugeneNine Wrote:  Its probably the rubber that presses the connections together. Press below the screen while trying to turn on, the rubber rots away and doesn't press the connection tight.

I have an SX with Keyboard issues that takes some pressing to get buttons to function, if they do, but on these two, pressing does nothing.

[Hiwi]

two suggestions:

1.) Try to do a longer reset. Connect the + and - battery clips and then pressing the reset under the right upper foot (put a needle in the hole) for about one minute.

(Some people put the batteries in reverse position, don't do that. The power on transitor may be blown!)

2.) Try pressing between B and C button under the display, then pressing ON

Ralf

[shoman24v]

(02-08-2023 03:26 PM)Hiwi Wrote:  two suggestions:

1.) Try to do a longer reset. Connect the + and - battery clips and then pressing the reset under the right upper foot (put a needle in the hole) for about one minute.

(Some people put the batteries in reverse position, don't do that. The power on transitor may be blown!)

2.) Try pressing between B and C button under the display, then pressing ON

Ralf

I will try the + and - connection reset again but leave it there for a long while.

I've tried pressing on the area above the top keys, nothing. Even fairly hard. Nothing indicates these should not power on, unless the keyboard really has no connection, which I find difficult to believe.

I have 2 like this, one brand new (not the one in the photo below) that won't turn on.

[Kiwi]

Did you try the reset button (with a paperclip) underneath the upper right or left rubber feet ? Normally it's marked with an 'R' on the plastic case under the rubber feet.
Another possibility is that some of the leaked battery liquid got into the keyboard layers and dissolved some of the circuity, resulting in a non working ON-key.

[shoman24v]

(02-10-2023 02:15 PM)Kiwi Wrote:  Did you try the reset button (with a paperclip) underneath the upper right or left rubber feet ? Normally it's marked with an 'R' on the plastic case under the rubber feet.
Another possibility is that some of the leaked battery liquid got into the keyboard layers and dissolved some of the circuity, resulting in a non working ON-key.

I have tried to reset with a paperclip, no luck.

I am wondering if it is an ON key issue. But, I have several other 48's with far more corrosion that work fine so am not sure that is the issue. Who knows...

[rprosperi]

To be clear, for the trick of pressing in the area above the keyboard and below the screen to work, you need to press down here and WHILE HOLDING THIS DOWN, also press the ON key. Pressing here enables contact between the keyboard and the cpu board but does not actually press any keys, it simply allows keys pressed while it's held down to be recognized.

As the foam under this connector degrades, more and more keys will cease to work unless pressing down in the strip between LCD and KBD. Some people have found that simply wrapping a strong rubber band around this area works well enough to use their 48 this way, but at least for me, it's really only a way to verify the machine and keyboard work, and then to have it repaired. I could not stand to use it on-going with a rubber band in place, it's just undignified and below HP standards....

[vaklaff]

The one on the photo looks a bit dirty around the ON key, maybe a good rinse under the key would help? I’d try IPA delivered from a syringe with a needle. Nothing to lose anyway…