HP97 battery pack rebuild

[Jlouis]

(02-16-2016 07:28 PM)Dieter Wrote:  

(02-16-2016 04:11 PM)Jlouis Wrote:  It did not work with the ac charge pluged in (exausted battery pack on).

This might not have been a good idea.
Quote from the museum's battery section here and here:

"Warning! Most models can be damaged if run from the charger without good batteries installed. Only the manuals for the HP 35 and 45 models say that it's OK to run without batteries, but many collectors feel that even those should have batteries installed for maximum protection and long life."

You wouldn't be the first one to fry his calculator this way.

(02-16-2016 04:11 PM)Jlouis Wrote:  It was erratic, sometimes on, most of the time off.

Uh–oh...

Dieter

Dieter, it was like that before I pluged in the batteries. It is working fine now, running with four AA rechargeable.

This warning does not apply to the 97..

I read many posts in the old forum, and many says although working erratically, power on a 97 with no or with exhausted batteries does not damage the calculator (this is also stated in the 97 service manual). There's a circuit that, although simple, protects the calculator.

The calculator now is functioning like a 67 with no card reader.

I'm planning to repair the printer and the card reader, but that's another chapter.

Thanks anyway.

Cheers

JL

Edited for better acuracy of information