HP Forum Archive 14

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HP-41CV Keyboeard Problem Message #1 Posted by Daniel Diggelmann on 28 Jan 2005, 3:27 a.m. Dear HP Enthusiast, i've got a HP-41CV in excellent cosmetic shape and very clicky keyboard that has a signle key which works unreliable. It sometimes works ok end then sometimes has to be pressed very hard to register. I openen the calc and saw the small hole to access the contact. I tried to gently clean it with a thin wire but this doesn't seem to help. Does anybody have a good idea. I don't see anything worng with it. Normally HP-41s have a very good keyboard. Thanks for any help Daniel

Re: HP-41CV Keyboeard Problem Message #2 Posted by David Smith on 28 Jan 2005, 12:21 p.m., in response to message #1 by Daniel Diggelmann Try cleaning it again a few times. Place a drop of alcohol on the hole and dip the wire brush in more alcohol. Some keys can be a bit stubborn about being cleaning and need the extra work.

Re: HP-41CV Keyboeard Problem Message #3 Posted by Artur on 28 Jan 2005, 3:07 p.m., in response to message #2 by David Smith Hi, After opening some HPs keyboards, I don't believe place a drop of alcohol is a good idea. The contact in 10 and 41 series is a little curved steel plate over the pcb and under a seal plastic. In some cases, may occur some oxidation, and alcohol may increase it, if it is not cleaned from the contact, as water will condense. If the problem becomes serious, I have only one way to fix it: breaking all melting plastics (carefully) that tight the PCB to the case, removing the plastic partially around the key and cleaning it with a small piece of fine sand paper. By the way, clean everything and, after that, put back the plastic and mount the pcb to the case. You really do not have to glue the PCB to the case, because 41 has the screws on the back! Good look! Artur

Re: HP-41CV Keyboeard Problem Message #4 Posted by David Smith on 28 Jan 2005, 5:55 p.m., in response to message #3 by Artur Alcohol will work just fine and not cause any problems. I have done this many hundreds of times. It helps to use the 91%+ isopropyl alcohol. Keep it off the display window... it will leave a white stain behind (but this can be polished off). Cutting apart the keyboard is a recipe for disaster. Getting it back together again so that it feels like new is very difficult.

Re: HP-41CV Keyboeard Problem Message #5 Posted by Daniel Diggelmann on 28 Jan 2005, 5:57 p.m., in response to message #4 by David Smith Many thanks for your inputs. I'll try the alcohol way first. and if it doesn't help i'l just drink it ;) I'll let you know my results. Cheers Daniel

Re: HP-41CV Keyboeard Problem Message #6 Posted by Daniel Diggelmann on 1 Feb 2005, 4:27 p.m., in response to message #5 by Daniel Diggelmann Juppie! my HP-41CV is registering every single keystroke after cleaning the contact with isopropyl-alcohol. It was so easy to do and i hope it will continue to work for a good while. Many thanks for your ideas and help. Cheers Daniel

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