Ronda Caliber 756

Ronda Caliber 756

Ronda Caliber 756

Manufacturer Ronda
Caliber Number 756
Movement Type Quartz, battery-powered, analog
Lignes 5.5”’
Jewel Count
4 or 1 (see below)
32,768 Hz
Battery Cell
379 / SR521SW
Battery Life
7 years
Accuracy Rating
-10/+20 sec/month
Hand Count 2
Hand Sizes
1.2mm / 0.7mm
Functions Central hours; central minutes
Country of Manufacture Swiss made / Swiss parts (China?)
Known Models
Nove Craftsman, TACS Time Glass, Invicta Cuadro (Add your watch to the comments below…)

The Ronda caliber 756 is small 2-hander quartz watch movement with a very notable feature – it has no crown/stem aka a back-set movement.

This affordable caliber is part of Ronda’s normtech line of quartz calibers, and is considered by Ronda to be a serviceable/repairable movement.

The 756 is available as a Swiss made or Swiss parts movement. The Swiss made version is gold plated with 4 jewels. The Swiss parts variation comes in a silver tone nickel plated finish with 1 jewel.

In Ronda’s own words:

“In the quartz domain, the “Normtech” line will be extended into a product with electronic time setting. The caliber 756 with size 5½’’’ with two hands is particularly suitable for jewelry watches and elegant timekeepers without a winding stem. The pressure point for electronic time adjustment is clearly perceptible. In addition, importance has been attached to user-friendly handling: adjustments are made in three clear steps and easy for owners to carry out. The new model is offered as Swiss Made and also in a Swiss Parts version and is already available.” –Source (Ronda Press-Release, March 2017)

How to set the time?

Instead of the traditional crown and stem system to set the time, the crownless cal. 756 has a feature that Ronda calls “Electronic Time Setting” (ETS).

It is a back-set style watch, but unlike the vintage back-set movements of the 60s and 70s, the Ronda 756 does not have a crown for setting the time. Instead, built into the back of the movement is a pressure sensitive metal arm that can be made to work with a custom button on the back of a watch case.

While there are only two hands to adjust, the 756 has three pressure points for time setting mode. In Ronda’s words:

  • Brief pressure up to two seconds – minute correction
  • Medium pressure between two and four seconds – hour correction
  • Pressure more than four seconds – continuous correction until corrector is released

Time-setting can only be achieved by advancing the hands forward. If you go past the time, you’ll have to go around again. Also note that since there’s no crown or seconds hand, this is a non-hacking movement. However, there is a possibility that a sort of “hacking” occurs while setting the time, but that is unconfirmed.

Changing the Battery:

Since the Ronda calibre 756 has a battery life of up to 7 years, you won’t have to change the battery often. When you do, the battery cell you’ll need is 379 (SR521SW).

Note: You may see other publications quoting a 5 year or even 10 year battery life for the 756. Caliber Corner has confirmed that Ronda’s official documentation states 7 years.

Replacement Prices:

Despite the unique technology in the 756, prices were found in the range of just $10 – $31.95 USD.

Dial Side:

Ronda Caliber 756 Crownless

Examples of watches with this caliber:

There are not many watches using the 756 yet. This is partly due to the fact that the crownless concept requires designing a unique case, as well as marketing and educating customers about why they should consider non-traditional watch unlike anything else in their collection.

Very few watch brands have ventured forward with the caliber 756. So far, some examples include Nove Craftsman, Invicta Cuadro, and the TACS Time Glass:

Caseback Executions:

Below are some of the ways these brands have designed the caseback around the push-button on the 756:

Nove Craftsman Ronda 756 Pusher

Invicta Cuadro 35314 Ronda 756 Pusher

Tacs Time Glass Caseback Ronda 756 Pusher

Ronda 756 VS ISA 257A:

It turns out that this concept it not unique to Ronda. ISASwiss, which is no longer in business, also produced a very similar back-set caliber 257A.

Both movements are metal with a similar shape in a 5.5”’ size form-factor (although ISA also had a larger version cal. K62A measuring 6.75”’. Both have two-hands, no date, and no crown/stem. Both use a pusher on the back to set the time. ISA also called theirs “Electronic Time Setting”.

One difference is that the ISA claimed a 5 years battery life (321 cell) and Ronda says theirs lasts 7 years on a new battery (379 cell). Also, the Ronda is taller at 3.1mm vs the ISA at 2.75. The ISA had 2 jewels vs 1 or 4 in the Ronda.

And of course the biggest difference is that you cannot buy the ISA anymore.

What remains to be undetermined is which movement came out first. And if the Ronda was released after the ISASwiss, did Ronda acquire (or become “influenced” by) the design for the ISASwiss version (or vice versa).

Update: The ISA 257A was found in watches as far back as 2015, specifically an Indiegogo watch called the MMT R Series. The caliber was also found in old ISA catalogs at least as far back as 2016. Ronda posted this press-release on March 17, 2017 mentioning their caliber 756.

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