How to regulate a mechanical watch (7S26 / 7S36 / valjoux 7750, ETA)

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caseback wrench
All images(except the biggest one at the bottom) and content DMP 2007

If your watch is particularly expensive, it is highly recommended that you get it regulated by a professional watchmaker.


The watch repair tools required to do the job can be bought seperately, or can be found together in inexpensive watch repair toolkits. Although 4 tools are shown on the left, you won't necessarily need to use all of them. Tool #1 & #2 are used to open up the watch. Tool #3 is a watch clamp. Tool #4 is actually just a bit of plastic cling-wrap used to wrap sandwiches. Click on the pictures to see a bigger picture.

Opening the case

If the back of the watch is screwed down(there will be notches equally spaced around the caseback - see pic #5), watch repair tool #1(with 2 prongs) is used to open it up. A tool with 3 prongs is better than a tool with 2 prongs because there is less chance of the tool jumping out of the notches. If the back of the watch is snapped down into the case, tool #2 is used to pry it open. In each case, the plastic cling-wrap should be used to cover the caseback, so that if the tools jump out of the notch, or slips, the caseback will not be scratched. Masking tape can also be used to cover the caseback. Tool #3 is used if you have trouble getting a good grip on the watch with your hand, and the watch moves around when you are trying to open it up. Alternatively, you can use leather golf gloves, or even rubber dishwashing gloves to get a better grip on the watch.

Note:If excessive force is required to remove the caseback, and the tool slips,or jumps out of the notch, it is highly likely that the caseback will be scratched, regardless of whatever is used to cover it. The cling-wrap or masking tape can only provide protection against light scratches. Be very careful, especially if you have little or no experience in using caseback removal tools, because scratching the caseback is very easy to do.

Warning: Tool #2 is almost like a knife. If it slips when you try to pry open the watch, it can seriously injure the hand holding the watch steady. So take precautions to protect the hand holding the watch.

Regulating the watch (see pic #6)

Once you've opened up the watch with the watch repair tool, all you need to do is to move the regulator bar that is directly in front of the +/-. If the + is on the left of the -, to slow the watch down, move the regulator bar left(clockwise), to speed the watch up, move the bar right(anti-clockwise). Some people like to use a toothpick to move the bar, I personally like to use a matchstick. But you can use anything to move the bar.

Note: Expensive watches, like Rolex and Patek Philippe etc. don't use a regulated balance system. Hence there won't be a regulator bar with a +/-. They use a free-sprung balance wheel, and you will need to look elsewhere for instructions on how to regulate it. Special tools are needed for free-spung balances. But why would you even attempt to regulate such a valuable watch yourself?

The regulator bar is very sensitive - a small movement causes a large change in the accuracy of the watch. Hence, it should be moved only a fractional distance, so that the movement is barely percepible.

Be very careful NEVER to move the bar on the left(with the single gold dot). This bar regulates the isochronism, which is the amount of change of accuracy over a certain period of time. For example, a watch with good isochronism runs consistently X seconds fast or slow each day, every day(all things being equal). A watch with bad isochronism runs X seconds fast one day, Y seconds fast the next, and Z seconds slow the next day. If you move this bar, you will need to see a professional watchmaker who will use a timing machine to reset it back to it's original position.

Also, be very careful NEVER to touch any of the springs, or other parts of the watch mechanism. The only part you should touch is the regulator bar.

Once you've regulated the watch, let it run for a period of say, 2 hours, and see how much fast or slow it runs, then mutiply the time by 12 to see how much the time will change over a day. Then regulate again, watch it for another 2 hours and so on.

Picture #6 shows the mechanism of a 7S26 movement, found in a Seiko 5. Not all mechanical movements will looks exactly the same, but they will look similar. All you need to do is to move the regulator bar that is directly in front of the +/- .


prying tool


watch clamp


cling wrap




7s26 movement

Before even trying to regulate your watch, give this a go:
positional regulation
All images(except the biggest one at the bottom) and content DMP 2007

My Watch Collection Seiko Dive Watches Internet Wristwatch Index Resizing straps