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34s:howto_timing_crystal [2012/01/22 17:09] (current)
vladhed created
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 +According to Kerem Kapkin:
 +I purchased the caps and the xtal from Digikey which succesfully added more accurate time function, here are the part details:
 +  * 300-8340-1-ND .68000 1.36 T CRYSTAL 32.768 KHZ 12.5PF SMD HTSUS: 8541.60.0010 ECCN: EAR99 LEAD: LEAD FREE ROHS: ROHS COMP COUNTRY/​ORIGIN:​ JAPAN CAGE: 0CS65
 +  * 445-1272-1-ND .10000 .50 T CAP CER 18PF 50V C0G 5% 0603 HTSUS: 8532.24.0020 ECCN: EAR99 LEAD: LEAD FREE ROHS: ROHS COMP COUNTRY/​ORIGIN:​ USA CAGE: 1ZFM7
 +According to Peter Mansvelder:
 +  * Backup up the calculator using ON + Store + Store
 +  * Take off the battery cover and take out the batteries
 +  * Take out the 5 screws: 2 on top, one in the middle, 2 under the '​antislip'​ strip at the bottom of the backside (outside the battery cover)
 +  * flip the calculator over and pry off one of the sides by slightly bending the plastic outer housing, the center '​metallic'​ part has to come loose. ​  First one side, then the top, then the other side. Actually this is so tight that I wonder where the screws are for...
 +  * Now you have the complete calculator front with the back of the PCB visible.
 +  * Top right you see a place for 3 components, marked C3, C4 and Y1. Each one has 2 copper-coloured pads.
 +  * Take the smallest soldering iron you can find (I use a Weller 12W with a pointy tip) and put some solder on them.
 +  * Take the 2 capacitors (I used 18pF ones in 0603 size, farnell article code 1612182), and solder them into place, using tweezers, a needle and a magnifying glass. It takes some practice, but it is not impossible: this is only my second time, and I haven'​t fouled up anything yet.
 +  * I used a SMD crystal too (farnell part number 1712821), but there is enough room for a regular '​tubular'​ watch type crystal, which is much easier. Same method, be careful not to let any solder flow too wide.
 +  * If there is any excess solder, clean it with a needle and some tissue (or better, use desoldering tape). I used regular solder, which is much too big for SMD use, so my work looked somewhat sloppy. But no matter, it worked!
 +  * Put the calculator back in reverse order, and try to set the crystal: ON+C+C. If the crystal is mounted correctly, you get '​OK'​ and you now have a much improved WP34s! In my example, there used to be almost 10 minutes to the hour discrepancy in time keeping, but now it runs like a clock!
34s/howto_timing_crystal.txt · Last modified: 2012/01/22 17:09 by vladhed