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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