HP38E not work

[Jorge Tucakov]

I have an Hp38E calculator that does not work because it was plugged into electricity without batteries. I was told to replace the processor and it was done, but it didn't work. When turning on, the display does not light up. Can anybody help me. Thanks. Jorge Tucakov

[teenix]

(04-12-2020 01:43 AM)Jorge Tucakov Wrote:  I have an Hp38E calculator that does not work because it was plugged into electricity without batteries. I was told to replace the processor and it was done, but it didn't work. When turning on, the display does not light up. Can anybody help me. Thanks. Jorge Tucakov

Sadly, a poor design when most people probably wouldn't think about batteries being in when the charger is applied, even though the manual mentions the problem, although changing the word "Note" to "Warning" might make it stand out more.

It is possible that some components in the power supply were damaged as well.

Maybe the new processor board is faulty or was not connected properly. I hope not, but worst case, the new calculator fault might be damaging the new processor.

It is hard to say without measuring voltages and signals around the circuit.


Edit: If it is a model with unsoldered chips, one of those might not be making contact with the circuit board properly.

cheers

Tony

[Steve Simpkin]

Some additional repair information. Also see links at the bottom of each page.
https://www.keesvandersanden.nl/calculat...pair_1.php
https://www.keesvandersanden.nl/calculat...pair_2.php

And if all else fails, this repair kit may be an option.
https://www.hpmuseum.org/forum/thread-13745.html