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 at 07:34 PM.