The Museum of HP Calculators

HP Forum Archive 19

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HP 16c - needs cleaning?
Message #1 Posted by Glenn Becker on 22 June 2009, 12:12 p.m.

I just received an HP 16c in cosmetically VG condition. It works fine, too ... except that the ENTER key has a strange, reluctant, "mushy" feel to it, almost as if there is dirt in there or something.

I have never opened a calculator in my life. How difficult would it be to open this unit up and clean it? And what is a safe method of cleaning?

Maybe I should just send to fixthatcalc, even though they have a big backlog/wait period.

Advice is welcomed. %^D

GB

      
Re: HP 16c - needs cleaning?
Message #2 Posted by Mark Edmonds on 22 June 2009, 1:44 p.m.,
in response to message #1 by Glenn Becker

I don't want to sound fatalistic about it, but from what I've learnt through recent experience of opening an 11C, I'd advise against attempting this as it is a seriously major job that involves breaking certain elements of the calc's construction.

My thread is just a few below this one:

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/forum.cgi?read=151913#151913

It contains some sage advice from other members as well as links to various pages with pictures and instructions. Access to the keyboard involves breaking over 40 "heat stakes" that hold the main PCB to the keyboard assmebly. If I was going to try this, I wouldn't do it on any Voyager that is in good condition!

I am sure that more experienced members can add to this to verify what I've written.

Indicentally, I used to have a 16C with a mushy On key yet never had mushy keys on my other Voyagers. Is this a strange feature of 16Cs?

Mark

            
Re: HP 16c - needs cleaning?
Message #3 Posted by Glenn Becker on 22 June 2009, 5:04 p.m.,
in response to message #2 by Mark Edmonds

Darn. Well, I wrote fixthatcalc -- we'll see what they say. Thanks for the response.

                  
Re: HP 16c - needs cleaning?
Message #4 Posted by Michael de Estrada on 22 June 2009, 5:31 p.m.,
in response to message #3 by Glenn Becker

Actually, FixThatCalc is a contributor to this forum, so maybe he will respond to you here later today.

                  
Re: HP 16c - needs cleaning?
Message #5 Posted by Glenn Becker on 22 June 2009, 10:16 p.m.,
in response to message #3 by Glenn Becker

Got a nice informative email from FixThatCalc re: the 'feel' of the ENTER key. Apparently it is due to the construction of the longer key & is quite normal.

But I was just playing around with the lil' beast and the display blanked out & doesn't appear to want to return. I'm hopeful it is just a matter of batteries, but who knows ... :(

GB

                        
Re: HP 16c - needs cleaning?
Message #6 Posted by Glenn Becker on 23 June 2009, 8:05 a.m.,
in response to message #5 by Glenn Becker

... not batteries.

I checked the "Self Tests" section of the manual and pressing 'D' and 'ON' simultaneously, then releasing them, brought the monster back.

                              
Re: HP 16c - needs cleaning?
Message #7 Posted by Mark Edmonds on 23 June 2009, 8:23 a.m.,
in response to message #6 by Glenn Becker

Regarding the "heat stakes" and breaking/removing them, has anyone tried melting them with a fine-tip solder iron? I am just wondering off the top of my head if it is possible to soften the plastic to make it easier to cut the "head" off and when it comes to reassembly, using a pastic adhesive to re-seal them? Feasable or not?

Mark

                                    
Re: HP 16c - needs cleansing?
Message #8 Posted by Klaus on 24 June 2009, 8:03 a.m.,
in response to message #7 by Mark Edmonds

I tried it with a HP-71b. I used a swiss army knive. Push the blade under the heatstake, then twist the knive. The edge of the mushroom-form will break off, but the center will remain intact. That means that after this procedure, the heatstakes are still as high as they were before, only the diameter of the mushroom head is reduced.

I put some foam in the case back to apply pressure towards the keyboard, works good enough now for me. I thought about re-melting a few heatstakes, there seems to be enough material left for that, but I did not test it.

                                          
Re: HP 16c - needs cleansing?
Message #9 Posted by Mark Edmonds on 24 June 2009, 9:26 a.m.,
in response to message #8 by Klaus

Thanks for describing that. Using foam as padding sounds like quite a sensible way of doing things and keeps it possible to do future maintenance without having to break re-sealed heat stakes.

Mark

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