Fine-tuning a Grand Seiko 9f

**JGJG** · 31st March 2019, 11:47

There doesn't appear to be a huge amount of information online about the procedure for adjusting the Grand Seiko 9f movement. Given some recent comments regarding the 9f on the BST Challenge thread, I thought I would share my experience.

Seiko says:

Regulation switching for precision control in a quartz movement
While mechanical watches possess a mechanism for fine tuning precision, these controls are impossible in most quartz watches.The 9F quartz movement, however, features a regulation switch that makes such precision control possible. If, because of environmental conditions or other factors, a watch ever becomes too fast or slow, the switch can be used to correct for such divergences. Owners who come to intimately know the individual tendencies of their watch over the years can quickly adjust the accuracy and continue to use it for years to come. Given the superb inherent accuracy of the 9F quartz movement, however, most will never need to know this adjustment function even exists. This is true to the high standards of Grand Seiko.

What it doesn't say, however, is how adjustment works so I thought I'd mention my own experiences on my own watch in case it is useful. Obviously, this is only intended as a set of observations for people who already understand what they're doing, the attendant risks etc...

Ultimately, it's really easy: you just turn the regulation switch clockwise to increase the rate and vice versa, exactly as it says on the tin. But here is some additional information that you'll need to know, which I found across multiple sources and have verified through my own adjustment:

1. Each graduation represents a 6 second per year adjustment (some sources say 8 spy, some say 6spy; most recently, Joe Kirk of Grand Seiko Seiko US confirmed 6spy in an interview - that figure accords with my findings regulating my own watch).

2. Adjustment must be to a full graduation. This is important info. There are very minor detents in the regulation switch travel. It seems that if the switch isn't left in a position aligning directly with one of the markers, then a correct regulation signal will not be passed to the movement and all bets are off. Take time to get the switch absolutely aligned; which leads to

3. Have a plan as to how you will operate the regulation switch. The switch is a plus shape as you can see above, and it is very small. To get the level of control required for (2) above, you will need some sort of coupling so as to apply pressure on both sides of the central pivot. I found that an odd size spring bar tool worked perfectly - one half way between the two widths of a Bergeon 6767.

Given the above, it seems that accuracy to within +/-3spy should be achievable for any 9f, this figure improving (potentially to 0spy) the closer your unadjusted variation is to a multiple of 6.

Hopefully this is of some use. I would be very keen to hear of other peoples' experiences in fine-tuning their GS quartz.

**JGJG** · 31st March 2019, 11:56

As an aside, it would appear that every 9f is supplied to the customer with the regulation adjustment switch in the centre position.

This would mean that the base accuracy (+/-10spy for the regular 9f, +/-5spy for the specials) is achieved through the matching of the quartz crystal and IC.

My understanding (but I would certainly appreciate any data to confirm or otherwise) is that the regulator switch will offer 6spy increments of adjustment for both the regular 9f and the specials.

This means that the special 9f would not enjoy any inherent advantage over the regular 9f, post-regulation. The ultimate post-regulation accuracy of either would merely depend on how close either unadjusted movement's variation was to a multiple of 6. i.e. a regular 9f operating unadjusted at +6spy could be regulated to 0spy, but a special operating unadjusted at +3spy could not be adjusted to a greater accuracy than +/-3spy.

Splitting hairs at this point, certainly. But then, that's part of the attraction of HAQ :)

**paskinner** · 31st March 2019, 12:08

If the ‘standard’ model could be reliably adjusted to better than 10 seconds (a year!), then why wouldn’t GS do that ? And why go to the trouble of selecting better samples of quartz for the 5 seconds models if you could just tweak them anyway.
I’m only guessing, but I suspect that adjustment is provided so that technicians can get the movement into the guaranteed range. Then the wheel is centred. GS certainly don’t intend for owners to break the seals and fiddle around. It would void the guarantee. So that can’t have been why the adjustment is there.
Anyway, they are usually more precise than the quoted range, so it’s pretty academic.
If you want better, the new Citizen 0100 will be plus or minus one second a year. That might be ‘adequate’.

**JGJG** · 31st March 2019, 12:23