Author Topic: Old Casio fx2000 calculator  (Read 2042 times)

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Offline alank2Topic starter

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Old Casio fx2000 calculator
« on: April 02, 2016, 04:32:48 pm »
I bought it today for $3 in a garage sale and have been playing around with it.  I fixed the power switch which was intermittent by cleaning it up, but the LCD display is hard to read except at extreme angles.  At normal angle it looks like all segments are on, but if you hold it at 75 degrees from normal you can make out the digits and it works.  I've had it all apart and took the LCD odd and cleaned up the contacts/elastomer between the display and pcb.  I tried some flux and resoldered all the connections around the IC.  I replaced the 3 caps which now that they are off look like 1uF with some 10uF ceramic ones I had laying around.  There is what looks like a SIP-6 and one more resistor where the pcb is marked 100 that measures 100 ohms.  The SIP reads all sorts of stuff so I'd probably have to take it off to measure it.  Any other ideas or things to try?
 

Offline sherlock

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Re: Old Casio fx2000 calculator
« Reply #1 on: April 02, 2016, 07:23:49 pm »
Here's a trick to try but you have to be careful doing it.  Sometimes the segments in the display loose their connections internally.  First, take out the battery.  Then take some aluminum foil and place it under the display and around it to protect the surrounding board and components.  Now take a heat source (heat gun or hair dryer) and heat the display.  You'll soon notice it gets black around the edges.  Keep heating until the whole display turns black.  Then let everything cool down for about 20 minutes or so.  The display should return to it's normal color.  Remove the foil, put the battery back in and try it out.  If that was the problem, the display should work normally.  I've done this on several different devices with about an 80% success rate.  I guess for a $3 item it's worth the shot.  Good luck.
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