HP-67 not working anymore

[christophe guerin]

Hi,
I recently had a broken HP-67: no batteries, and a rubber wheel.
I changed the batteries and the wheel and everything worked fine for a week.
I was able to use the cards, do any operation, etc.
And all of a sudden, things started to go wrong: the display didn't match what I put on (ex: just after OFF/On, key 1 gave -266665616540 01)
Sometimes funny things happen on the screen : CoC-E or 0C-E.
Sometimes nothing appears at all, although the current is flowing (about 150 mA).
Can someone give me advice on how to repair this machine?
Thank you for your help

[teenix]

(02-16-2021 01:59 PM)christophe guerin Wrote:  Hi,
I recently had a broken HP-67: no batteries, and a rubber wheel.
I changed the batteries and the wheel and everything worked fine for a week.
I was able to use the cards, do any operation, etc.
And all of a sudden, things started to go wrong: the display didn't match what I put on (ex: just after OFF/On, key 1 gave -266665616540 01)
Sometimes funny things happen on the screen : CoC-E or 0C-E.
Sometimes nothing appears at all, although the current is flowing (about 150 mA).
Can someone give me advice on how to repair this machine?
Thank you for your help

If you can remove the back and hold the battery in and turn it on, leave it for a few minutes and then check for any warm chips on the circuit board. Sometimes this gives an indication of a failed chip, like the ACT, (nearest the bottom of the circuit board).

Check the circuit board for corrosion and other visible problems.

150-200mA seems reasonable when 0.00 is displayed.

cheers

Tony