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HP Forum Archive 02

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HP-97 printer problems
Message #1 Posted by Erik Wahlin on 2 Jan 2000, 1:16 a.m.

The display on my HP-97 goes blank when print X or the paper advance is used. I was wondering if anybody knows what could cause this problem. Thanks

      
Re: HP-97 printer problems
Message #2 Posted by Steve on 2 Jan 2000, 5:58 a.m.,
in response to message #1 by Erik Wahlin

Does the paper advance when you try to advance it?

Does the display come back after the advance has completed?

Does printX print the display correctly?

My display blanks for a short period while advancing or printing. I think this may be correct operation. The nicads have not been charged for a while in my HP97, but still have a reasonable charge.

I've not done too much printing (any at all actually) as I have only a single roll of paper. This is the second time I've printed with this calculator, and the first time I've noticed the behaviour.

            
Re: HP-97 printer problems
Message #3 Posted by Jan H. Bos on 2 Jan 2000, 6:47 p.m.,
in response to message #2 by Steve

I have just checked a HP 97 on NiCad power and the display goes blank while printing, but only for half a second. An other point. As almost everybody is low on thermal paper rolls, can there be an alternativ? Thermal fax paper works, but it does not come in the right reel size. Being a paper engineer, I might be able to solve this problem, but what are you guy's prepared to pay per roll?Regards, Jan

      
Re: HP-97 printer problems
Message #4 Posted by DaveC on 2 Jan 2000, 6:56 a.m.,
in response to message #1 by Erik Wahlin

Erik, Its normal for the display to blank when printing. As Steve suggests if the display does not resume then there is a problem. Maybe you could confirm if the display comes back when printing is complete.

            
Re: HP-97 printer problems
Message #5 Posted by Erik Wahlin on 2 Jan 2000, 9:27 a.m.,
in response to message #4 by DaveC

Thanks for the replies. The display remains blank, and I have to switch the calculator on and off.

There is a small circuit board inside that seems to be associated with the printer. Could the fault be here? I just received a "parts" 97 and might try changing out this small circuit board.

                  
Re: HP-97 printer problems, problem solved
Message #6 Posted by Erik Wahlin on 3 Jan 2000, 1:36 a.m.,
in response to message #5 by Erik Wahlin

I tore my HP97 printer apart and discovered the problem. There are two wires running from the small circuit board adjacent to the printer. The wires go to a magnetic switch. Basically, two metal vanes inside a small glass tube are brought in contact when the print head, which has a small magnet is brought in close proximity. This is when the print head is in the rest position. I discovered that the magnet was missing from the print head. Luckily I had another HP97 for parts and could see the problem.

                        
Re: HP-97 printer problems, problem solved
Message #7 Posted by Andrés C. Rodríguez on 3 Jan 2000, 7:59 a.m.,
in response to message #6 by Erik Wahlin

Such magnetic switches are called "reed switches".

                              
Re: HP-97 printer problems, problem solved
Message #8 Posted by Wayne Brown on 3 Jan 2000, 8:39 a.m.,
in response to message #7 by Andrés C. Rodríguez

In the 8th grade (1968) I had a lot of fun with a magnetic reed switch that I bought at Radio Shack. I hooked the switch up to a small battery and light bulb and hid it in my shirt pocket. Then, with a magnet concealed in my palm, I waved my hand across my pocket and made the light blink on and off. It really amazed the other kids at school, none of whom had ever heard of a reed switch and had no idea how I was doing it.

These days, if a kid brought something like that to school, somebody probably would think it was a bomb and call the police...


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