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Miyota 8200 - The Ultimate Workhorse? (Part 1)

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  • Miyota 8200 - The Ultimate Workhorse? (Part 1)

    It's the same motor that powers your Magrette, your Armida, your Invicta, your ProMaster and many others including German made wristwatch! It may not be so beautiful to behold, but like the other Japanese watch maker, engineering and technology is its priority. Like its contemporary, the Seiko Watch Co., Citizen Watch Co. had come a long way and perfected their engineering prowess in watch making and produced several chronometer models that proved to be among the Japanese' finest.

    The Caliber 8200 is the longest running caliber in the production line, probably the most abundant caliber ever produced of all watch brands combined. It spanned about three and a half decades and still being produced to this day. Though it came with different versions it remained without any modification from the start and proved to be well-engineered, very accurate, very durable, and most of all, economical. So, that's how the game is played. In order to stay abreast, keep a low profile, remain the same, and carry a big tic-tac.

    Seiko reaped the fruit of patience and perseverance and now they have the technology that tipped the balance. For Citizen, the new caliber 9015 is just the resumption of fine engineering they were doing in the mid-20th century and until now they are concentrating on their equally pioneering technology: Eco-Drive. But it is electronic and the clamor for the revival of mechanical watches is growing more and more everyday. I am just hoping that Citizen regains enough resources and follow suit with a different approach: the Ultimate Mechanical Technology at half the price. Let's all cross our fingers

    Split personalities? The Miyota Cal. 82XX is the same caliber with several designations. 8200 is a 21-Jewels, 21,600 vph., day/date, automatic movement with manual-wind provision. 8203 is a 21-Jewels, 21,600 vph., day/date, automatic movement with manual-wind provision. 8205 is a 21-Jewels, 21,600 vph., date, automatic movement with manual-wind provision. 8210 is a 21-Jewels, 21,600 vph., date, automatic movement with manual-wind provision. 8215 is a 21-Jewels, 21,600 vph., date, automatic movement with manual-wind provision. Can you spot the difference?
    01 Citizen-Miyota Caliber 8200A.jpg

    With the rotor out of the way, a very neat movement comes into view. Held by just three screws, the power train bridge holds both the power train mechanism and the automatic mechanism. One nit, you must disturb the power train mechanism when replacing the auto-ratchet wheel. If you work like a wispher you may be able put the bridge back without a sweat.
    01a Inside View.jpg

    Citizen opted to integrate the chapter ring onto the dial. The paint on the dial is a true matt black due to the use of a pitch black pigment that almost absorb light. A good choice of material here. The markers are raised with lumes bounded by chromed edges. The hour hand and minute hand and the seconds hand is unique to this particular dive watch model. Note that the red painted seconds hand is a replacement of the ruined original.
    02 The Dial.jpg

    The calendar font is also unique to the caliber 82XX. I can tell if a watch is powered by a Miyota. The calendar mechanism incorporates two animal-shaped components: the swan lever (yellow arrow) that advances the the calendar wheels, and the nessy lever (red arrow) that acts as spring for the swan lever.
    03 Calendar Disks.jpg
    04 Calendar Mechanism.jpg

    The swan and the nessy out of the loch. Note the swan-like shape of the manual advancer for the calendar wheels (right). It is actuated by the clutch wheel that has two tabs that when turned rocks the advancer lever. The lever on the left is a spring that repositions the advancer lever to its rest position clearing the way of the teeth of the calendar wheels. I call it nessy as it resembles the head of the Loch Ness Monster. Note the other head sometimes breaks at the location pointed by the yellow arrow. I've encountered about a dozen of this breakage already and the wandering break-away head often binds everything under the dial rendering a malfunction.
    05 The Swan & The Nessy Levers.jpg

    The set mechanism, all made of stamped steel, is straightforward in design and is simple and very efficient. The yellow arrow points to the set lever, set in place by a robust set lever spring (blue arrow). The yoke (red arrow) is not tensioned by a spring but operated by the set lever pin sliding in a guide slot. Note the clutch wheel below in its adjusting position. The swan lever is shown in place (green arrow) and the spring lever (cyan arrow).
    06 The Set Mechanism.jpg

    The power train bridge is a single piece, robust and properly designed. Red arrow point to a full bearing of 14 miniature steel balls without spacers in between them. Yellow arrow points to the tension spring for the floating seconds pinion. Blue arrow points to the barrel arbor pivot, worth mentioning since it did not indicate any wear after about 34 years of continuous work. This is where all other designs fail due to wear and affects the movements performance greatly. Wearing of this hole would bind the barrel wheel against the bridge and the main plate. I never encountered such problem on all 8200's that I've worked with.
    07 The Bridge.jpg

    The power train layout is carefully thought of and the spaces are maximized paving way for an optimized layout. There are no negative (unused) spaces. The yellow axis denotes the crown down position and the red axis denotes the common axis of the three centers of the balance wheel, pallet fork and the escape wheel. In a crown down or crown up position, the pallet fork is in equilibrum minimizing, if not eliminating, positional and beat errors. The barrel is big enough to keep it running for 45 hours. What is notable with it is it keeps the 8200 isochronized well within 24 hours. Accidental or smart engineering?
    08 The Power Train.jpg

    (I "type" a lot and due to the forum's limit of 10,000 words per post I splitted this post into two parts, so please, proceed to Part 2)
    Last edited by JunMel; 12-10-2011, 07:34 PM.
    Tempus fugit...

  • #2
    Miyota 8200 - The Ultimate Workhorse? (Part 2)

    The heart of a Citizen. 8200's balance wheel is among of the best size-to-weight proportioned balance wheels. Not too big and not too heavy, at 21,600 vph, makes this particular design one of the most consistently oscillating balance wheel around. Take note that inertia, centrifugal force in a gyroscopic motion greatly affects the proper oscillation of a balance wheel. An overly sized and heavy balance wheel suffers slow momentum when flung around such as when the arm is swinging vigorously, affecting the oscillation of the balance wheel and adversely affecting the timing of a watch. Properly proportioned balance wheel in size-to-weight is the key in the excellent performance of a watch. Together with the calibers 6XXX series of Seiko, this is where the Miyota 8200 endears itself to me. One more plus is the use of the most efficient shock protection ever, the Parashock system. The balance staff is virtually indestructible in the event of accidental droppage. The very thin olived hole jewel that virtually eliminates friction and the robust cap jewel contribute to the excellent performance of the balance wheel assembly.
    09 The Balance Assembly.jpg

    The balance staff is quite long and perfectly proportioned to the diameter and thickness of the balance wheel. This proportion controls the gyroscopic effect that can disturb the proper oscillation of the balance wheel, considering the type of shock protection employed here.
    10 Balance Wheel Profile.jpg

    Jumping Jack. The only annoying "feature" of the 8200 is its stuttering seconds hand. Citizen rectified this with a specially shaped seconds hand, by enlarging the counter balance tail and in the process made the tip of it a little adorable by putting a lumed triangle. Not bad, though a better internal solution should've been substituted like employing a sandwiched third wheel, eliminating the use of a pressure spring. Thankfully, Citizen eliminated Jumping Jack in the new caliber 9015.
    12 The Floating Seconds Pinion.jpg

    The main plate is beautifully machined with lotsa holes and pits Note the extra protection given for the barrel wheel. Its delicate teeth is protected by leaving a piece of metal which is unmindfully machined to oblivion in other calibers.
    14 The Main Plate.jpg

    The dial side of the plate is also carefully machined to accomodate all vital functions.
    15 The Dial Side.jpg

    While the movement is in the spa, let's have a peek inside the case of a Citizen diver. The walls are thick which, obviously, is designed to withstand high water pressure. Note the concave crystal seen in this view. The screwed case tube is about the size of an Oyster (Rolex) case tube, about the same design and construction and about the same double-locking gasket system!
    16 Inside Cavity.jpg
    17 Threaded Case Tube.jpg

    This freshly COAed caliber 8200 is minty again and performing an average daily rate of about +0.40 seconds per day after more than a week of settling. I think I've done my best on this particular 8200A. 34 years in service, it's former master has already retired and found a new caring master in me. I may refinish its case in due time but as for now, I'll just have another look at its battle scars and replay the battles it witnessed deep in the forests of Northern Luzon.
    18 The Freshly COAed Movement.jpg

    Here are some samples on how you may want your 8200 to be.

    The new standard finishing on all ProMaster Automatic dive watches. Note that for new Citizen dive watches, the 8200 assumes the 8203 designation without any modification except for the finishes.
    19 Miyota 8203B.jpg

    You can also engrave it and plate it in gold and apply chaton (with "s" if you wish) as done in this exotic 8200 by Hemess® Watch Co.
    21 Gilded & Decorated.jpg
    22 Chatoned & Engraved.jpg

    The new Miyota 9015 signalled the retirement of the 8200. This caliber promises an even more accurate timing by being a hi-beat movement at 28,800 vph, 24 jewels, hacking and better decorated. Will it break the record of 3 decades in production? Only time will tell
    20 Miyota 9015.jpg

    What are the reasons why I chose the Miyota 8200 to be commended in this manner? I summarize: First, accuracy and durability. Second, engineering and technology. Third, economy and abundance.

    Have a nice weekend.
    Last edited by JunMel; 12-10-2011, 07:39 PM.
    Tempus fugit...


    • #3
      Very, very cool! Thanks, JunMel! So, does my 8203 diver have the version with the blued rotor?
      Not yet keen to open her up


      • #4
        Surely it is Enjoy your new ProMaster.

        Kind regards.
        Tempus fugit...


        • #5
          found the diff online.
          mine apparently has the 8203A (shown here). the blued version is 8203B


          • #6
            That's the same version I have in my NY2300. The blue version is probably in the AutoZilla.
            Tempus fugit...


            • #7
              Wonderful piece JunMel

              Thank you. I enjoyed it immensely.


              • #8
                Is the miyota movement better than the 7S26 movement?


                • #9
                  Super writeup!

                  Thanks Jun. Fascinating.



                  • #10
                    Thanks, Jun...and a question...

                    We have the Miyota 8215 in the Magrette Bronze watches. Any interesting variations on this?

                    The rotor has a peculiar rattle to it.



                    • #11
                      Thank you all guys. I am hoping these kind of threads will benefit everyone.

                      @Tyler: That is not actually a rattle but the sound coming from the bumping action of the rotor turning the ratchet wheel in one direction leaving the other direction freewheeling. The force of the mainspring rebounds the rotor, hence the bumping sound. Note that the rotor turns on a full bearing and its very sensitive that only a slight movement sends the rotor to jerk. Miyota did not rectify this over the years since it poses no problem in the automatic mechanism's performance. You can only hear this when you hold the watch near your ear, otherwise you won't notice it.

                      @Barometer Watch: Seiko's are worse on this that you can actually hear a grinding sound. To make matters worst, the bearing employed on a Seiko has only 5 to 6 steel balls that tend to wear over the years and the rotor would grind on the plate and the bridge.

                      In my 40 years experience servicing watches, except for those destroyed by water entry, I haven't seen a worn out 8200 bearing in normal use. I remember replacing bearings on a Seiko 5206, a couple of 6309's and dozens now on 7XXX series, but never on 8200's.

                      Except for those Seiko calibers with jeweled barrel arbors, most Seiko calibers tend to eat the bushings for the barrel arbor. Whenever you see brassing on the barrel wheel (worst scenario) suspect a heavily worn-out arbor bushing. If the watch is left alone in this situation the click wheel will eat on the bridge and the barrel binds on the bridge and the plate giving an erratic timing. Seiko 7S26/36 is the weakest caliber regarding this as it doesn't have a replaceable barrel arbor bushing. The workaround is to punch near the arbor hole to compensate for the wear. I say "hole" and no bushings on 7S26/36.

                      This is what greets you when the barrel arbor bushing is already worn out. Good timing for me since it was only beginning and the barrel wheel hasn't brassed yet. Note the wear pointed by the red arrow. The bushing is worn-out on its side near the wear on the bridge. It is replaceable though, so no problem here.

                      There are plenty of replacement bushings. And since this Seiko 6139 (courtesy of Mr. Sparks) is priceless to me, I also replaced the third wheel bushing with a jewel. Now it runs perfectly. Red arrow points to worn-out bushings.
                      Tempus fugit...


                      • #12
                        My compliments for the overall best article I've yet seen on any watch subject. You confirm my feelings about Citizen quality, especially after the last 3 Seikos I've had have stung me (2 kinetics & a 7T92).
                        A question about the 8200A...I just lucked into my first one, probably a 70's model, hooded lug SS 3 hand w/ gold colored dial & plastic crystal. To my amazement, it still works and keeps halfway decent time, tho a bit fast. Upon opening, I find the adjustment tab set way over on "+". Would I be right in guessing that cautious readjustments back toward the "-" mark will bring better accuracy--or is a good cleaning the answer? Many thanks in advance.


                        • #13
                          Thanks Jun, LOVE Citizen !

                          "So Many Watches / So Little Time"


                          • #14
                            Thanks Kurt, citchu. Surprised to read an old thread!

                            @citchu, there are several factors affecting the accuracy of any watch. In the worst scenario, worn-out parts due to neglect or depriving a seemingly well-running watch of a much needed COA. Note that COA should be periodically given to a watch for a preventive maintenance. In the case of your 8200A, someone might have thrown the regulator to "+" position which gives a fast rate. If you center the regulator between the + and - and acceptable timing is acheived, then it is done. But if you happen to observe an erratic rate, then your watch must be submitted for COA. A good timing machine can spot errors in real time and it is only here that you can confirm if the watch requires a much needed COA.


                            If you are familiar with the service history of your watch, I advise you to have it serviced every 5 years at most, that is if it is an ISO rated water resistant dive watch. For most watches with only 30 meters to 50 meters rating COA must be conducted periodically every 2 to 3 years. In every COA, have the gaskets replaced to ensure water resistance.

                            COA - Cleaning, Oiling, Adjusting.
                            Tempus fugit...


                            • #15
                              Very interesting article indeed. I've just purchased a Citizen Automatic NH8250-53X from Japan (sold out locally) that uses the 8200 movement. I wasn't aware of its pedigree but I am now. Sounds like I've invested wisely :-)