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Seiko 0624 Trimming Screw

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retrowrist

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Seiko 0624 Trimming Screw

Post04 May 2014, 17:09

Hello Everyone,

I have a Seiko 0624 module that runs incredibly fast, probably gains a minute every 2 days. I have examined the possibility of using the trimming screw to adjust the speed accordingly, but I am unsure if the trimming screw requires a special screw driver. If any of you could give me any suggestions of how much I need to turn the trimming screw right/left for proper adjustments in gain/loss I would be very grateful.

Thank you all,

- Patrick
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Ole Joe

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Re: Seiko 0624 Trimming Screw

Post04 May 2014, 21:15

retrowrist wrote:Hello Everyone,

I have a Seiko 0624 module that runs incredibly fast, probably gains a minute every 2 days. I have examined the possibility of using the trimming screw to adjust the speed accordingly, but I am unsure if the trimming screw requires a special screw driver. If any of you could give me any suggestions of how much I need to turn the trimming screw right/left for proper adjustments in gain/loss I would be very grateful.

Thank you all,

- Patrick


Hi Patrick,

If the trimmer cap adjustment is slotted, simply use a small jewelers type blade screwdriver to turn the adjustment. If using a PPM meter or frequency counter to set the correct PPM/Freq., it is best to use a non-metallic or insulated type tuning tool, otherwise body capacitance will skew the reading. Not sure which direction to turn the adjustment to correct the oscillator frequency, depends on how the trimmer capacitor is installed. Gaining about 1 minute in two days is equal to 182 minutes/year or 346 PPM (Parts/Per/Million) higher than the oscillator frequency should be running. In terms of oscillator frequency it should ideally be tuned to oscillate at 32.768KHz. Your oscillator, being about 346PPM high, is running at about 32.779KHz. Normally, the trimmer capacitors value will allow tuning of about +/- 2hz either side of 32.768KHz center frequency. I doubt that you will be able to tune the trimmer capacitor enough to correct the 11Hz difference. What may have happened is that the quartz crystal has aged over time, watch has been dropped shocking the quartz and altering its frequency from the original setting etc. What I would suggest is turning the trimmer capacitors adjustment a full 180 degrees and see if it changes the time gained or lost in a 2 day period. Make a mental note of which direction you turn the adjustment for reference. If it looses time in the two day period, which would be good, then readjust the trimmer in the opposite direction from the reference direction in small increments. IF this works, continue the same routine until you get it as close to not gaining or loosing time. Another suggestion is to take it to a jeweler who has a PPM meter or instrumentation device that will indicate if the quartz can be adjusted to the 32.768KHz. center frequency when the trimmer capacitor is adjusted. If you can't find a jeweler with that type of device, PM me and I can do it for you.

Best Regards,

Joe

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