Omega de Ville cal 1325 ref. ST 192.0002 needs a service. I bought this one
on eBay.
Omega De Ville story and tech info
I didn't treat quartz watches as serious collectables in the
past. But some time ago, I discovered its beauty (from an engineering
point of view) :) :). Still, my main hobby is connected with mechanical
watches, but I am not afraid to get also an interesting quartz watch.
This kind of exciting peace is for sure Omega de Ville from 1976.
Cal 1325 circuit components.
Omega de Ville ref. 192.0002 has a stainless steel case and sapphire crystal glass. An exciting movement feature is that crown has a push button inside. To change minutes user has to push the button in the crown. The crown has to be pulled up and rotated (like in modern watches) to change hours. There is no sweep second.
Calibre 1325 is a quartz-controlled stepping motor movement with a 32768Hz (32KHz) quartz oscillator - like in modern quartz watches.
How Omega Quartz cal 1325 works:
1. Battery power causes the crystal oscillator to vibrate with a very high frequency (32768 times per second). The high crystal frequency is a great natural feature. Because of it, a quartz watch can be very accurate.
2. Microchip detects oscillator frequency and converts to one electric impulse per second.
💡Tech details:
There are several frequency dividers (flip-flops) inside the microchip. Each one of them divides the frequency by two. Output from a previous
divider is an input for the next divider. As a result, the chip generates one electric impulse per second:01: 32768 ÷ 2 = 16384
02: 16384 ÷ 2 = 8192
03: 8192 ÷ 2 = 4096
04: 4096 ÷ 2 = 2048
03: 8192 ÷ 2 = 4096
04: 4096 ÷ 2 = 2048
04: 4096 ÷ 2 = 2048
05: 2048 ÷ 2 = 1024
06: 1024 ÷ 2 = 512
07: 512 ÷ 2 = 256
08: 256 ÷ 2 = 128
09: 128 ÷ 2 = 64
10: 64 ÷ 2 = 32
11: 32 ÷ 2 = 16
12: 16 ÷ 2 = 8
13: 8 ÷ 2 = 4
14: 4 ÷ 2 = 2
15: 2 ÷ 2 = 1 output impulse
In other words, the first divider changes its output 16384 times per second, the next divider 8192 times, and the last one only once per second.
This amount of logic in the chip - 15 dividers, each with several
transistors, was not available till the 70s. The first quartz clocks were
very expensive and looked like a closet because logic took a lot
of space before an integrated circuit was discovered (in 1958). This particular Omega
chip from the 1970s consists of about 300 transistors.
3. Electric impulse powers stepping motor.
4. Stepping motor turns movement wheels
Omega 1320/1325 Stepping motor
Typical vintage Quartz movement issues
Almost 50 years is an extremely long time for an electronic circuit. So
watch that survive this long may have some electronic issues like:
- Broken path in the circuit board and similar issues (like broken
battery handle).
- Damaged stepping motor.
- Damaged quartz oscillator.
And also:
- Mechanical issues like dirty (not serviced for ages) movement.
Diagnosis - Why the watch is not working right
I opened the case and found several issues:
- Broken battery contact (missing fragment).
- Corrosion on a preserved fragment of the battery contact.
- Broken path in the circuit board (chip pin).
- A small part of the battery contact in the movement locks the second wheel.
- Detached setting lever.
- Corrosion on a preserved fragment of the battery contact.
- Broken path in the circuit board (chip pin).
- A small part of the battery contact in the movement locks the second wheel.
- Detached setting lever.
And:
- Bad quality back gasket.
Detached setting lever.
Corrosion on the battery contact
Blocked wheels by metal filings (battery contact fragments).
Broken paths/microchip pins
Donor of parts
Not required! :) A lot of issues to fix - but no parts are needed (instead of a new back gasket).
The repair
I started by checking connections between circuit elements. I used a multimeter with a resistance measurement feature. There were two broken paths between the microchip and other
components. I used soldering iron to repair paths. The circuit board is made of plastic, so it is easy to deform it during soldering. Maybe safer would be to use liquid silver to fix connection issues. Then I cleaned the battery contact. Only a part of the contact is present
in the battery holder, but still, it should be enough to power the circuit board.
I soldered all microchip pins.
The setting lever was placed in the correct position. The movement was cleaned.
Next, I removed two small metal parts which blocked the wheels. I cleaned the movement and oiled jewel bearings with swiss watchmaker oil. I placed the setting lever in the correct position. The setting lever was not damaged - I think that somebody (in the past) pulled up the crown with too big force.
Summary
The result is quite good. The main goals were achieved :)
- The watch keeps the right time.
- The watch doesn't stop.
- The time setting feature works ok.
Vintage Omega quartz with push-button - after repair
Tools
- Movement holder
- Metal and plastic tweezers (a good quality number 2-3)
- Rodico cleaning putty
- Screwdriver set (a good quality watchmaker set with precise blades)
- A good quality small paintbrush
- Watch hand lifting levers
- Watch hand press set
- Watch oilers
- Watchmaker oil
- Case opener/pocket knife
- Pegwood
- Eyeglass
External links
Electronics-tutorials - flip-flop (microchip element)
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