Accutron Batteries
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Battery Installation   Timing your Accutron

 CAUTION:  If you found an old Accutron in a drawer and put a battery in it, you may be quite pleased to find that it runs, but may I suggest that you remove the battery immediately and have the watch serviced before putting it back on your wrist. For an explanation please visit the  Q & A Page  

The correct cell replacement for your 214 is a #387/394 (silver oxide), which is the exact size of the old #387 (mercury) cell and comes with a plastic sleeve which is necessary to prevent an electrical short in the Accutron circuit.

 The electronic circuit in your 214 (commonly referred to as the coil) was designed to run on 1.35 volt mercury batteries which are no longer sold in the USA. Currently available silver oxide batteries produce 1.55 volts. Perfect adjustment of the index mechanism was not as critical with the lower voltage of mercury batteries as it is with silver oxide batteries. The higher voltage (+0.2V) can cause some movements to run too fast. If this happens to your 214 it is usually because  the adjustment of your Accutron was borderline in the first instance and you will have to have the movement professionally adjusted.

COIL MODIFICATION: Is your Accutron running way too fast?  A readily available 1.55V silver oxide battery usually works well and most 214's can be adjusted to run properly without any difficulty but there are some movements which can only be described as over-active. The adjustment of an over-active movement with a 1.5V battery is so tenuous that any external force will cause the movement to speed up. This explains why some watches run great on the dresser but too fast when worn while others will run well for a while until a hard bump causes them to slip out of adjustment.

The bottom of each 214 tuning fork tine was notched at the factory to set the frequency (click photo). A relative few have tuning forks that were cut to the thinner end of their tolerances. This was OK when the magnets were energized by 1.3 volts but at 1.5 volts these forks are over-active. This causes them to index two teeth instead of one either periodically or with every stroke. Previously the only way to correct the problem was to replace the tuning fork with one that has thicker tines but that is not a reliable solution to the problem. Experience has shown that quite often, the watch will run well for months after the fork is swapped, but the movement is still susceptible to speeding up after suffering a severe shock.

Fortunately there is a way to permanently solve the problem. A diode which lowers battery voltage in the circuit by 0.2 volts can be installed in the coil. This is really the best possible solution to the problem. The watch will perform as it did when new, battery issues will be resolved, and the life of the coil will be extended. Whether actually needed or not, this inexpensive modification is highly recommended. It is not noticeable and it is reversible.


The micro-thin coil wire used in your 214 is already working against the ravages of age. Running an over-voltage of .2V through the delicate wire can't possibly be a good idea. The other delicate components in the circuit will not benefit either. Even if your 214 runs well with the new batteries, the longevity of your coil could be at risk. There is no longer any doubt that all 214's will benefit from a reduction in voltage back to the original 1.35 volts.


INTERMITTENT BATTERY CONTACT: If your 214 kept good time right up until the battery was replaced but has been losing time ever since, the problem is most likely poor battery contact. This is a fairly common occurrence which can often be avoided (or corrected) by installing the battery properly.


 INSTALLING A #387/394 BATTERY IN YOUR ACCUTRON 214 

Check the voltage of the new battery to make certain that it's not defective. It should measure 1.5V. If the battery is ok, install it by following these instructions carefully.

 1)  Unscrew the battery hatch, and carefully place the battery into the watch as follows: Angle the battery slightly downward, aim the lowered edge toward the outside of the case and insert the battery, lower edge first so that it falls into the recess easily.

Battery Insertion
View of the battery as it should appear when placed into your 214s battery compartment (unprinted side up). The printed (+) side is facing down.

 Important
: Hold the battery with your fingers or non conducting tweezers only.



 2)  Make certain that the plastic insulator is not hanging up on the battery nest, preventing the battery from having solid bottom contact. After dropping a battery into your 214s battery compartment, it may appear to be seated properly even when it is not. Always press the center (metal part) of the battery down firmly until it seats against the bottom contact. This is necessary because the plastic spacer is often too large to enter its opening thus preventing the bottom of the battery from seating all the way down.  
 
 3)  Check to see that the contact spring installed on the under side of the battery hatch has not been flattened. Observe whether  the spring moves down freely when pressed, and that it pops back up when released. The spring must provide positive pressure against the top of the battery. 

Left: Early 3 finger battery contact spring (1960/1961)
Right: Common battery contact spring (1962 on)

EarlyBatterySpring.jpg (30132 bytes)                           BatteryHatch.jpg (30017 bytes)     BatterySpring.jpg (30536 bytes)
 Click on thumbnails for a larger image and use your back button to return

 4)  Screw the battery hatch back on being very careful not to cross-thread it. Do not over tighten the hatch, Slight pressure on the new gasket is all that's needed.  

 IMPORTANT:  TO PREVENT DAMAGE TO THE COIL, MAKE CERTAIN THAT THE METAL PART OF THE BATTERY IS SEATED FLAT AGAINST THE CIRCUIT BOARD. IF YOU FEEL PRESSURE BEFORE THE BATTERY CAP IS SCREWED ALL THE WAY DOWN, STOP, REMOVE THE CAP AND RE-SEAT THE BATTERY.

Continuing to screw down the battery hatch in that situation will invariably put pressure on the coil through the battery well before the hatch is closed fully and the coil will break at the adjacent mounting screw.

This will be the outcome if you fail to heed this warning


 STARTING YOUR WATCH

Many 214s will start spontaneously when a new battery is installed but some will not. Over the years the permanent magnets on the tips of your tuning fork may have lost some of their strength. If this is the case you will need to jump-start the movement. A sharp smack with the palm or knuckles of your hand at the 3 or 9 oclock position should cause the tuning fork to start to vibrate. Once started the watch will perform normally until the battery dies.

 

ACCUTRON BATTERY CHART 

Caliber

Old Mercury 1.35V

New Silver Oxide 1.55V

214

387

387/394 & AccuCell-1

218

343

344

219

343

344

221

388

329

230

343

344

224

343

344


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Copyright  2002 by Martin Marcus. All rights reserved. These pages may not be copied without written consent.