HP-25: More common problems?

[Juergen Rodenkirchen]

Having read the messages suggesting a "warm up phase" for certain HP-25 machines in order to make them work, I've encountered another problem with my machine: When switching on the machine, the display is sort of flickering (the display appears somehow like during running a program, that is). Sometimes, it even seems to be dead. A "warm up phase" doesn't help at all. But after awitching the machine on and off repeatedly a few times makes it finally work. I'm not sure whether this is sort of an electronic problem as discussed in the article by Katie (I think) or if it's just a mechanical problem concerning the on/off switch. Does anybody have encountered similar problems and/or has advice on how to fix it? Thanks for your time!

[Thibaut.be]

How fresh are your batteries ?

[Juergen Rodenkirchen]

Well, I actually encountered the problem when operating the machine with the charger plugged in. The batteries were completely discharged and I gave it only a few minutes (5 or so) to recharge, though. Do you think that a longer recharging period is supposed for the machine to work properly (even if the the charger is connected)? However, I'm going to charge the batteries for a longer period tonight and try again ... Thanks for your input!

[David Smith]

This is THE symptom of a bad or missing battery pack. NEVER EVER operate a Woodstock machine (especially a 25C or 29C) in this condition. On the "C" series machines they do not even need to be turned on to cause problems. The internal voltage rises above the destruct level of some of the internal chips... hence my pile of over two dozen bad ACT chips that I have accumulated over the years.

If at all possible charge your Woodstock batteries in the external charger or an already blown machine.

[Juergen Rodenkirchen]

Dave, thanks a LOT for your warning! I immediately unplugged the machine (which is an ordinary one, i.e. not a "C")! Fortunately, the machine seems to be intact as a test showed. However, I will follow your advice and charge the pack inside a different machine which is already broken (the memory chip doesn't work any more). Guess what? The "rebuilt" battery pack comes from the broken machine, so I guess you are absolutely right. Many thanks for your advice again!