I hope you enjoyed these blasts from the
past.
As for the future, we will continue our
work on the quartz watches and plan for our lathe workshop starting at noon on Sunday, September 23. We also have the Woodsboro Mart coming up on Saturday, September 15.
Thanks to all for your participation and
continuing great support of HAM.
Best regards,
David
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Secretaries
Report
The July 9
regular meeting began promptly at 7:40 PM. In attendance were:
Stan Craig, Earl Knight, Robert Rothen, William McLane Sr., George Tresansky, Al Takatsch, John Reilly, Dan Spath,
Brett Louis, Bill Miller, Jerry Kincaid, George Painter, Jack Kennan, Dave Grau, Dave Hennemann and new member Mike Dale.
Introductions
were made and the Treasurer’s Report was given by Stan Craig. Stan noted
that we have paid our AWCI dues and supported Jerry and Dan for the national meeting in August, so our treasury has taken
the usual annual hit for around $800. The report was accepted. The Secretary’s report was accepted as well.
Old Business:
Dan Spath delivered a fruit basket to HAM member Bob Myers, who was very grateful to receive it. He was particularly happy that we made him a life-time honorary member of HAM.
A motion was
made to have the HAM treasury pay the dues of the next president of HAM as an incentive and reward for taking the position. The motion was seconded and past unanimously.
The motion will go into effect with the next election in November.
New Business:
Bob Rothen made members aware of the Cottone Auction in Franklin PA to take place July 20 & 21. Bob intends to go and bring back a lot of rare tools, some horological, some not. Franklin is north of Pittsburg.
There was no
new business so the door drawing was made and won by Mike Dale who picked his own number.
Mumbling and protest were heard throughout the hall but the drawing stood. Just
kidding Mike.
After the meeting
Stan Craig gave a talk on quartz watch repair. The following notes were taken. Please accept any inaccuracies as the information was coming hot and heavy.
Stan noted
that almost no information was available regarding quartz watch repair until Henry Fried’s book around 1988 and S. La
Rose printed a parts book. The quartz movement vibrates at 32768 times per minute,
accounting for their accuracy over the normal 300 vibrations per minute for a conventional watch. Early quartz watches jumped
every 10 to 30 seconds in order to extend battery life.
Crystals have
to age for about a year before they are used. If they are not aged then the watch
tends to lose time for the first year then settle down. Early on, parts were
replaced individually, now whole circuits are replaced as a unit to save time and money.
Most parts now cost as much as new movements. Various parts can be tested
for resistance and continuity using a VOM that has at least 20,000 ohms/volt sensitivity. Sometimes if the coil has a break
on the surface windings, it can be repaired with one of the proprietary coil mending fluids.
Lithium batteries were 3 volts, Mercury 1.35 volts and Silver 1.5 volts. Some
early quartz watches had a mechanism to regulate the gain or loss of time, but modern quartz watches have the trimmer built
into the circuit board and automatically adjust themselves.
To begin repairs,
first clean the outside of the case, even a small amount of debris can stop a quartz movement.
Work the dial side first, remove dial, hands, day/date wheel etc., take all except the setting parts. Remove minute wheel and cannon pinion. Remove the guard over
the coil, remove coil, remove the circuit board cover and board. This usually
has 4 screws, one of which acts as a ground. Note that three of the screws are
the same, one is short. Remove the battery and insulator, remove the setting
cover, the bridge over the train wheels and the hack lever. Then remove the train
wheels. Do not remove the rotor with regular tweezers, use antimagnetic tweezers
and grab it by the pinion.
Do not oil
the train wheels esp. if they are plastic. The train is a floating train and
has no lateral pressure on the wheels. Do not put the rotor in solvents, just run the outside edge over some Rodico to clean
any iron filings the may have been attracted to it. Clean rust if you see it. Clean all parts as usual.
To reassemble,
place the stem with crown attached making sure it snaps back and forth. Replace
the rotor in stator. Place another rotor or small magnet under the rotor outside
the plate to hold the rotor in place. This will keep the rotor from jumping around
while you are replacing the wheels. Replace wheels, hack lever and train-wheel
bridge, align all and replace screws – lightly at first until you are sure all pinions are in place. Replace the setting parts, setting cover, circuit and coil and coil cover.
The watch should run at this point. Apply 1.5 volts to check. Do this
at the battery contacts. Time-out the watch before you put the dial side in place.
Very little
oil is needed in quartz watches, but put some on the canon pinion post and post of minute wheel so the watch will set smoothly.
The oiling of a quartz watch is a subject for another lecture. Put calendar parts
in next. This can be hard to do. Next
place the hour wheel and day disk in place making sure the trips are aligned. Put
on dial and hands. Done!
VP Ramblings,
Last meeting
Stan gave an informative presentation on Quartz Watch Problem Diagnosing. John asked that I give my take on what we learned
about.
-First look
at the watch, is the second hand moving or pulsing. Did the customer have any particular complaints why they brought it in
for repair. Do the hands move freely when setting. Write down observations.
-Lay watch
on pulse and frequency tester. Does the counter show quartz vibrations and coil impulse? Write down results.
-Assuming that
problem exists, clean watch carefully to remove dirt before opening. A properly working watch can be caused to fail with another
problem by loose dirt finding its way into the mechanism. Open case and again clean dirt from around seal that didn't come
off earlier. Again observe the movement for any obvious problems.
-Take out battery
with non conductive tools and test voltage, it should be about 1.5volts or voltage specified by manufacturer. Note results.
It might just need a battery, but lets test the electronics anyway.
-Test resistance
of coil which should be about 3000 ohms or 3K of resistance. If open or shorted note the results.
-Set tester
to drive the watch simulating a battery driving the watch. It supplies a voltage and current reading of both which help in
analyzing the movement. Apply the probes to the battery input connections making note of proper polarity. A properly working
watch will show current flow in the microamps(ua). The tester shows a decreasing current flow of approximately 5 to .5 ua,
after firing the coil the reading jumps back up to 5ua . My own impression of why this happens is the electronics starts off
charging a capacitor that’s discharged and as it reaches firing voltage the current reduces to almost zero before the
electronics fires the coil. At the point the coil if fired, the capacitor discharges and the ua are then back up to a high
level.
-It should
be noted if the movement is dirty it will draw excessive current giving shorter battery life. This is shown by a large increase
in current usage way above the normal 3 to 5ua. Readings can be as high as 10 to 30ua. If this is the case the movement should
be cleaned. We didn't cover that yet.
-If all readings and operation is normal than install new battery and place watch on test stand to analyze frequency
of quartz. This tests the accuracy of the movement, ex: how many seconds per hour or unit of time that the watch will run
slow. It should be noted that quartz movements have the ability of self correcting, you will notice a constant rate of frequency
for a few seconds. If the watch needs to correct, it is shown by a jump in frequency. Stan says the watch will do this for
the life of the watch. I haven't yet understood how the watch does this, I say this because the watch only has 1 crystal.
If the frequency is off slightly and needs to be corrected, what reference point does the electronics use to measure the correct
frequency? Also if the watch knows the correct frequency why did it have to correct it?
My take on this is, and I may be wrong, is the quartz frequency always is correct, that's why a quartz crystal was
used. The problem comes with driving the mechanical portion of the watch. I believe every now and it pulses the coil but the
gears are not advanced. The electronic feedback generated by the coil is sensed which should correspond with the pulses given
to the coil. It keeps track of this and when enough error is accumulated the circuit gives an extra pulse to compensate.
OR ANOTHER THEORY
The frequency of the quartz is analyzed as a very even frequency, the quartz input circuit contains a missed pulse
counter that senses a missed quartz vibration. When the counter sees enough missed vibrations it then gives an extra
fire or pulse to the coil to make up for lost quartz vibrations. As that point the counter zero's itself out and the process
begins all over again.
If I am wrong with my crazy theories will someone please explain this to me in detail. Inquiring minds need to know.
See you guys at the next meeting.
Al Takatsch
