Questions about my dead(almost) 48S

[Waon Shinyoe]

Hello I'm looking for help for my poor 48S...

I forgot to take the batteries out when I set it aside for one or two weeks. The next time I picked it up, it was dead. Strangely, there was NOT ANY sign of battery leakage or corrosion. But when I press ON, the screen blinks once and then shows nothing. Then I try to press random keys. There is beep when I press down each key but the volume, or the frequency, gradually goes down as time goes, and finally my 48S doesn't work at all. Every time I put in batteries it goes like this.

I tried to repair it. I followed the post in hpmuseum, clipped the reset hole and pressed on for a long time. It didn't work. Then the strangest thing happened. The screen was HOT! I was so afraid that my 48S would burn apart...

Can anyone help? What happened to my 48S?

[Paul Berger (Canada)]

That does not sound good, if it is running down a set of batteries quickly something is drawing a lot of current, and the would also account for the heat. It is not likely that the heat is coming from the LCD itself but rather something under it, and that is where the processor and LCD driver chips reside. I am afraid this does not look good, since there is nothing else in that area it would seem likely that a chip has failed, but the only way to know for sure is to open it up.

[jch]

Did you tried to remove batteries and short power terminals ?

If you are lucky, it may be only a "latch up" ?

(07-25-2015 07:29 AM)BarryMead Wrote:  It is also possible that the input protection diodes went into "Latch Up" when the TX voltage went .5V above
the power supply voltage. To clear the "Latch Up" state remove the batteries and short the 3V and GND terminals of the battery for a few seconds to drain any power supply capacitors. Then reinstall the batteries to see if the calculator wakes up again. If you had left the calculator in the "Latch Up" state for any length of time it is likely that the batteries suffered a significant drain, and it might be wise to start with a fresh set of batteries after the battery-removal / Discharge procedure. Good Luck, Barry

Regards.
Jean-Christophe.

[Waon Shinyoe]

(08-12-2015 07:59 PM)jch Wrote:  Did you tried to remove batteries and short power terminals ?

If you are lucky, it may be only a "latch up" ?

Good news: Yeah it works! I think it powers up and functions well! Thank you!

Bad news: the LCD is still dead... no display at all...

Update:
I tried to operate it. I was sure it worked. But then I found the screen, again, was hot! I removed batteries instantly. Quite strange.