Post Reply 
HP41 refuses to switch ON after some time OFF
02-18-2016, 09:31 AM
Post: #1
HP41 refuses to switch ON after some time OFF
Hello All,

I restored an HP41C "Tall keys" not long ago:

I changed the badly corroded flex circuit by one of Diego's replacementes and added 3D printed battery holder, modules and side covers from shapeways. The calculator has been working flawlesly for about two months, but recently it refuses to be powered on after a "long" OFF time (lets say a couple of days). It usually simply does not respond to the ON button, but once it happened that it just beeped. a short beep for every ON press and nothing else.

Pressing clear+ON doesn't seem to change anything, but shorting the battery contacts do; after that it will turn on with a "memory lost" warning, an work normally until it is left OFF again for a long period.

Posts are OK, inside is corrosion free, flex circuit is, obviously, clean and shiny, as are the contact pads. I've not dared to look at the lower end flex circuit, as the control board is held in place by nuts, and I fear to strip the thread, but I'm quite confident the problem doesn't come from it (after all, when "reset" it works normally).

Any experience similar to this? Maybe some electrolythic cap will need replacing? (I feel that those are the most age-affected components, after having repaired several TV's and computer boards just renewing the caps, strangely, all recent models, old ones seem to last longer).
Find all posts by this user
Quote this message in a reply
Post Reply 

Messages In This Thread
HP41 refuses to switch ON after some time OFF - ElectroDuende - 02-18-2016 09:31 AM

User(s) browsing this thread: 1 Guest(s)