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HP 25 Display error - Printable Version

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HP 25 Display error - reiner - 02-22-2002

Hello out there,
my 25 shows -when switched on- only one or two zeros.
The position manipulate herself when I switch it on a second time.
Any with an idea ?

My 21 has a bad LED at position eight - I cleaned the contacts without an result. Couldt this be a chip failure?


Re: HP 25 Display error - David Smith - 02-22-2002

Around 85 percent of similar failures seem to be caused by a defective ACT chip (the 22 pin, 0.4 inch wide chip). Most likely the bad digit in the LED is a bad LED display module (80%) or a bad cathode driver chip (20%).

Re: HP 25 Display error - Spice_Man - 02-23-2002

Are such chips available today, aside from scavenging from another calculator?

Re: HP 25 Display error - David Smith - 02-23-2002

Nope, like 99% of all chips in HP calculators the only way to get them is to salvage another machine.

Re: HP 25 Display error - reiner - 03-01-2002

Thank you for information.
I changed the LED - same result, the 8th digit dosnĀ“t
light up on my 21.
best regards

Re: HP 25 Display error - David Smith - 03-01-2002

If you want an HP25 that works and are willing to gamble your HP21, then you can remove the HP21 ACT chip and use it in the HP25... something not recommended unless you (or somebody you know) are quite skilled at desoldering and soldering.