HP Forum Archive 14

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HP-67 display trouble: Help! Message #1 Posted by Albert on 25 Feb 2005, 8:49 p.m. Hi everybody, After a successful card reader gummy wheel replacement, sometimes the display shows a very brilliant row of " --------------" (middle segment) when I turn on the machine. Even if the calculator is off, when I push some keys, a dull red middle segment twinkles (-). ¿How can I do? ¿How can I fix this problem? Thanks in advance, Albert

Re: HP-67 display trouble: Help! Message #2 Posted by Tony Duell on 26 Feb 2005, 5:46 a.m., in response to message #1 by Albert The 'g' segment (the one in the middle, used for the -ve sign) has a separate current control circuit, which is pair of transistors in the corner of the logic board. That, in turn is controlled by a resistor on the keyboard/display board. Bad contacts between the keyboard/display and the logic board can cause this. Since you've just taken the machine apart to repair the reader, I would check the pins between the 2 boards carefully.

Re: HP-67 display trouble: Fixed! Message #3 Posted by Albert on 26 Feb 2005, 7:34 p.m., in response to message #2 by Tony Duell Many thanks Tony, There was a bad contact between the power plug-in and the display PCB (the ground wire). Now, the machine works fine. Albert

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