Ronda Caliber 4120 B

Ronda Caliber 4120.B

Ronda Caliber 4120 B

Manufacturer Ronda
Caliber Number 4120.B
Movement Type Quartz
Size 12 1/2”’
Diameter Total
Casing Diameter
Jewels 7 or 3 (see below)
32,768 Hz
Battery Cell Number 395
Claimed Battery Life 50 months
Stem S401-2025
Hand Count 4
Hand Sizes
1.5mm x .90mm x .20mm
Functions Central hours; central minutes; small seconds at 3:00; big date at 6:00; alarm at 9:00
Hacking Seconds?
Swiss made or Swiss parts, assembled in unknown
Known Models
Invicta Russian Diver III (Add your watch to the comments below…)

The Ronda caliber 4120.B is a quartz watch movement with a small seconds subdial at 3:00, a double-digit big-date indicator at 6:00 and subdial at 9:00 with an alarm.

Ronda Caliber 4120 B Macro

Watches with this caliber will have a button on the case around 4:00 for modifying alarm functions.

Ronda Caliber 4120b Alarm

Swiss Made Vs Swiss Parts:

According to the Ronda website, there are two versions of this caliber 4120.B quartz movement: a Swiss parts version with 3 jewels and nickel plated finish, and a Swiss Made 7 jewel version with gold plated finish (above).

Ronda Caliber 4120 B Macro Jewels

Battery Info:

The 4120.B take a battery cell number 395. The expected battery life for a fresh cell is about 50 months. This will depend on how often you use the alarm.

If you buy a new battery here, your purchase supports the site.

This movement also has a power saving mechanism with pulled out stem (essentially hacking seconds), which lowers the rate of consumption by approximately 70%. In other words, if you are not going to wear your watch for an extended period of time and want to preserve the battery, you can pull the crown out. Just keep two things in mind: make sure your watch is in a safe place with the crown pulled out. You don’t want it to catch on something and break the stem. Also, don’t keep your watch in storage for too long, otherwise you run the risk of the battery leaking acid into the movement.

When changing the battery, be careful when you unscrew the screw… the wishbone style battery strap becomes a cantilever and will fling the screw across the room if you don’t put something over it. One trick is to hold the strap down with your finger (only when wearing gloves or finger cots) or Rodico, then carefully remove the screw with tweezers.

Ronda Caliber 4120b Battery Clamp


You may notice that there are two springs sticking out of this caliber.

Ronda 4120b Springs

The springs send current to the Piezo buzzer style alarm indicator on the caseback.

Ronda 4120b Caseback Piezo Buzzer

What is a Piezo buzzer?

“Piezo buzzers are simple devices that can generate basic beeps and tones. They work by using a piezo crystal, a special material that changes shape when voltage is applied to it. If the crystal pushes against a diaphragm, like a tiny speaker cone, it can generate a pressure wave which the human ear picks up as sound.” –Source

Replacement Prices:

Ronda states that this is a repairable metal watch movement, however, if you need to replace it the prices online range from $48.95 (Swiss parts) to $66.95 (Swiss made) at the time of this post.

Watches with this movement:

The movement featured on this page was found in this Invicta Russian Diver III Alarm watch. If you have a watch with the Ronda 4120.B, please add it in the comments below…

Ronda Caliber 4120 B Invicta Watch

Additional Resources:

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Gonzalo García López
Gonzalo García López
3 years ago

Hola necesito un movimiento Ronda 4120 B date 12 donde lo consigo?

Ronda Movement List Watch Movement | Caliber Corner
1 year ago

[…] 4120.B – Small seconds, alarm, big date […]

Aaron Herman
Aaron Herman
4 months ago

I have a Tag Hauer Formula One 2-hand, 2-subdials, one is running seconds and the other an alarm, and a big date at 6 o’clock. The Ronda 4210.B movement Tag Heuer utilizes is a workhorse while the watch still remains dressy.

7 hours ago

Tag Heuer Formula 1 WAZ111A uses the same movement.

Seagull Caliber St19

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