Electronic, Not Electric
The Timex Model 87, caliber 882, is a 13½ ligne electronic watch movement. The miniature energy cell, time drive, date indexing, hand setting, the case and the crystal are identical to the Models 84 and 85.
A switch actuated by the hand setting mechanism disconnects the flow of current in the electronic circuitry when the crown set wheel is pulled out into the set position. In this position the watch is stopped, allowing time to be set to the exact second, and the energy cell is not being discharged.
The Timex electronic has an hourly beat of 21,600. The large balance has a temperature compensating hairspring system and the rate can be adjusted in the usual way by moving the regulator. It can be checked in all positions on a normal watch rate recorder, and dismantled and repaired with conventional tools. For checking the battery voltage, a high ohm voltmeter of about 20,000 ohms per volt is sufficient.
Exploded View
The circuit group at 4010 through 4160/3 is what replaces the Model 84’s contact spring, and much of it is insulating hardware: washers, insulators and the hairspring clamping block.
Disassembly for Cleaning
Cell, Crystal and Movement
Remove the energy cell. To avoid damage to the watch case, the energy cell cover should be opened only at the spot indicated on the caseback, where an arrow and the words “lift here” are stamped. Check the voltage: any cell reading less than 1.5 volts, or one known to have been in service in excess of one year, should be replaced.
Remove the crystal using a Timex crystal lift or conventional crystal lift. The movement can now be removed through the front of the case.
Note the locating notch in the bezel seat (A) and the corresponding key on the balance bridge (B).
The Crown Set Wheel
The crown set wheel remains with the caseback. An automatic coupling device connects it with the setting stem when the movement is replaced in the case.
Should it be necessary to remove it, lift the crown set wheel to the “stop” position.
Spread the retaining spring open with the tips of tweezers and push the crown set wheel down through the rear of the case. If necessary, the retaining spring and gasket can now be removed.
Fitting the Retaining Spring
To examine the function of the movement, place it on a movement ring and clamp the energy cell in place with an energy cell retaining spring, available on request from the Timex Material Sales Division.
To assemble the retaining spring, loosen screws A and B, lift the switch insulation with a screwdriver and insert the spring between the switch insulation and the hand setting spring, then tighten screws A and B.
The Cell in Place
One end of the retaining spring depresses the stopping spring fixed to the movement and allows the balance to be turned freely.
The Circuit
The electrical impulses given by the electronic circuit are transferred to mechanical driving impulses for the balance in the same manner as the Model 84. The impulse current flows through the balance drive coil, and the magnetic south pole of the coil is attracted by the north pole and repulsed by the south pole of the permanent magnet system. The electronic circuit is triggered by the voltage which is induced in the coil of the balance when moving through the permanent magnet system.
The Circuit Diagram
Two transistors, four resistors, one capacitor, the coil, the battery and the stop switch.
Where Everything Sits
The permanent magnet system together with the shunt bridge can be rotated out of position so the balance and hairspring are visible. To do so, remove one screw (C); it may be completely removed by removing both screws (C).
After removal of the permanent magnet, the balance bridge and balance can be removed. Screw (D) serves to adjust endshake of the balance and is fixed in place with epoxy.
Before disassembling the balance bridge, screw (E), which connects the electronic circuit to the balance bridge, must be removed. The bronze hairspring must then be removed by loosening screw (F). The hairspring stud may be pressed out of the balance bridge to separate the bridge and balance.
The crown set wheel stem (G) is also the staff of the minute wheel and is connected to the crown set wheel on the caseback through a clutch device.
Setting & Stopping
Running Position
The crown set wheel is depressed to its running position. The clutch disc is kept out of engagement with the stem and the setting spring is depressed, so the projection on the setting spring is kept out of engagement with the stopping finger of the balance.
The nose (H) of the stop switch must touch the rivet (J) of the setting spring. Electronic switched on.
Set Position
The clutch disc now engages with the square portion of the stem and couples the stem and crown set wheel, allowing the hands to be set. This position also allows the setting spring to move upwards and butt against the stopping finger on the balance, stopping it.
The nose (H) of the stop switch must be clear of rivet (J) of the setting spring, interrupting the starting current of the electronic circuit. Electronic switched off.
Adjusting the Setting Spring
Move the crown set wheel upwards so the clutch disc is just out of engagement with the square portion of the set stem, resting against the bottom of the square. In this position the projection on the setting spring must contact the stopping finger on the balance by the amount shown.
When the crown set wheel is pulled into the set position, the stopping finger on the balance must be in full contact with the projection on the setting spring. For this adjustment, bend the setting spring in the area marked (K).
The nose (H) of the stop switch must be clear of the rivet (J) on the setting spring by at least one half to one and a half times the thickness of the setting spring. If necessary, adjust this clearance by bending the setting spring in area (L).
Removing the Clutch
Lift the plastic sleeve from the stem with tweezers as shown. The tip of your finger should be placed on top of the plastic sleeve during this operation to avoid loss of the sleeve. Next remove the clutch disc, then the screw “A” and the setting spring.
Lifting the Circuit Out
The electronic circuitry can now be taken off by removing screws “B” and “M”.
Lift the circuit base as shown and turn it in the direction of the arrow until the stop switch clears the train bridge. Take care that the stop switch does not become damaged.
The Index Train
When the balance moves counterclockwise it moves the indexing lever to the left. The lever contains a steel “D” shaped pin which advances the index wheel forward one tooth, after which the lever comes to rest against the banking pin. The tip of one tooth on the index wheel is attracted and held in position by the magnet. When the balance moves clockwise the pin moves the index wheel backwards slightly until it clears the tooth, and magnetic attraction then retracts the wheel to its original position.
The Two Positions
When the index wheel has been moved forward three teeth, one tooth of the two-toothed pinion fixed to it engages the sweep second wheel and rotates it forward one tooth. That one tooth rotation, aided by the click, provides the one second jump of the sweep second hand. The safety finger ensures that no more than one tooth will index at a time.
The Third Wheel Friction
The dial train friction is provided by the third wheel assembly. A friction washer is interposed between the third wheel pinion and the third wheel. It is important to carefully lubricate this as indicated after cleaning.
The Arresting Magnet
The index magnet may be removed to check the train. During removal of the magnet, the index lever must be in the position shown in illustration 1.
Refitting the Circuit
Locking the Stop Switch
Position the electronic circuit as shown, above pin “P”. Push down the stop switch to a level slightly below the nose of the train bridge “R”.
While holding the stop switch down, move the circuit to its final position over pin “P”. This will lock the switch into position below the nose of the train bridge.
Now assemble the setting spring and the screws holding the circuit board.
Use the disassembly procedures as a guide for further reassembly. When replacing the movement into the case, pull the crown set wheel out into the set position to facilitate entry of the setting stem into the crown set wheel.
Cleaning & Lubrication
1. The movement including the electronic circuit may be cleaned in the usual method using normal watch cleaning and rinsing solutions. The balance must be cleaned separately to prevent damage to the coil. Do not clean the energy cell with any liquid; if necessary it should be wiped with a dry cloth only.
2. After cleaning, any particles adhering to the magnet should be carefully removed before assembly. A piece of scotch tape rolled to a point will be found useful. This process should not be used when the movement is assembled, as there is danger of severing the lead wires of the balance coil. The other parts must be free of particles, especially steel or nickel which would be attracted by the magnet.
3. The movement should be re-oiled in the normal manner using only high grade watch oils. Elgin M 56 b is used in factory assembly. Under no circumstances should oil or grease containing silicone be used.
The points requiring lubrication are the jewel bearings and pivots of the train wheels and balance; the minute wheel and set stem bearing surfaces; the steel “D” shaped pin on the index lever; the surface of the click which rests against the sweep second wheel; the third wheel assembly; and the pipe of the crown set wheel, so the lubricant will seep down to the rubber waterproofing gasket which surrounds it.
4. The best performance is achieved if the hairspring does not vibrate between the pin and key of the regulator. The outside edge of the hairspring should be in light permanent contact with the inside edge of the regulator key. Make sure that both hairsprings have good clearance to all other movement parts, for example the balance bridge and the upper shunt of the driving magnet.