First successful open heart surgery

[Sedi]

Yesterday I adjusted a Casio for the 1st time - never had the guts before and it also wasn't necessary as all of them run well within specs but I received a PRG-100 that was over one second slow a day. First I thought about selling it but I like the watch so much and it was on my wish-list forever so I gave it a go.
When I opened it I didn't even know if it has a trimmer screw but lucky for me it has one. First you have to remove the strap however - the plastic back-protector is attached to the backplate (looks like it's simply snapped on).




Strap removal is fairly easy as it has those metal pieces that hold the springbars - I used a paperclip to push in the springbars.
You can also see that it's a "sample" watch with the engraved "S" on the backplate.


The trimmer screw is to the bottom-left of the battery.



I took my most precise Casio (AE-1000 which runs at about 1-2 sec + / month) and started adjusting - I gave the screw a little turn counterclockwise to speed it up - then used the stopwatch of the AE-1000 and started it once the PRG-100 reached the full minute so that they were perfectly in sync - then watched it for an hour or two - the whole process took about a half day with repeated turning of the trimmer screw and then checking against the stopwatch. Once it seemed to be in sync with the AE-1000 for a longer time I closed it back up and synced it with my GW-6900. After one day it still shows almost no deviation from atomic time - operation successful and I can finally enjoy this great watch!
Some thoughts on the process:
- I had to turn quite a bit before I noticed any change for the better - in the end it was almost 1/4 turn
- I ordered some JIS-type screwdrivers as I slightly messed up the backplate screws - which is bound to happen with Philipps-type drivers as they're just the wrong type - sure won't happen next time with the new screwdrivers
- It was all worth it as I hate a digital watch that runs slow and I didn't want the watch to be "spoiled" for me as I really like this model - a review of the PRG-100 will follow soon.

cheers, Sedi

[Sedi]

Finally the right tool for the job:




So I opened it one more time as it was still running a little slow (yet much less so than before the operation) - the screwdrivers work great - no comparison to a Phillipps. I should have gotten some of those long ago.

cheers, Sedi

[cpl]

Wow! Did not know you can adjust a digital watch.

[Sedi]

Not all of them have a trimmer screw however but if they do it's pretty straightforward. From what I know the newer Casio models don't have one anymore.

cheers, Sedi

[BlackNomad]

The trimmer screw is to the bottom-left of the battery.

Thanks for the post, Sedi! I can't see "S" on the back plate, but I see "AC" at 10 o'clock - does it have an Air conditioner?

[Sedi]

Yes, if it gets too hot the fan turns on but one should be careful if said "s..." hits it.

[Sedi]

Seriously though - the "AC" is the contact for the reset procedure - after changing the battery you need to shorten the battery with the AC-contact - some say it stands for "all clear" but I'm not sure on that. The "S" for sample can be seen on the 1st 3 pics - it's on the backplate of the watch right across the Protrek logo.

cheers, Sedi

[popoki nui]

Seriously though - the "AC" is the contact for the reset procedure - after changing the battery you need to shorten the battery with the AC-contact - some say it stands for "all clear" but I'm not sure on that.

I'm certain; it does indeed stand for "All Clear". And as you know, that is what happens when you touch the battery + to that connection: it basically reboots the watch, clearing all the previous settings.

~Sherry.