Ronda Battery Clamp and Screw

Anyone who has decided to venture into DIY territory with changing the battery of a Ronda quartz chronograph movement knows all too well how much of a PIA it can be.

The pros of the Ronda quartz chronograph calibers mostly outweigh the cons, but there is one big con that can stop even the best watchmakers in their tracks during a battery service… that is the clamp and screw design.

The clamp is a wishbone design with two stepped down prongs that slide under the movement’s main plate (technically called the electronic module cover), and the other end is secured in place by a single flat head screw. While the design holds the battery cell securely in place, it is not user friendly whatsoever.

When loosening (or replacing) the screw, the wishbone shaped clamp becomes a catapult, prone to launching itself and the screw across the room. If you’re lucky, you might find the screw after a few hours of searching on your hands and knees with a flashlight – you may even recruit the help of friends and family to help you look for it, offering them a reward if found. A magnet sweeper can also be a helpful tool in this situation, but in most cases no matter who helps or what you use, the tiny screw is gone.

Don’t beat yourself up about it. It happens to the best. The only difference is that the pros usually have a box of spare parts. Time is money and professional watchmakers with a lot of jobs to complete do not have time to be on their hands and knees searching for screws. It’s easier to grab a replacement from the drawer and maybe the lost screw will turn up at the end up the day when floor gets swept. But this info doesn’t help the DIY-from-home amateur who doesn’t have the luxury of drawers full of spares. Keep reading…

Ronda battery clamp and screw replacements:

If the pro tips above are too late and you already lost your screw, find the replacement parts list below. Sometimes you can find replacements on eBay or from watch parts suppliers. If you cannot find the parts anywhere, always remember that you can try to find a broken watch for parts/repair to take the clamp and screw from (just make sure that isn’t the reason it’s being sold as broken). You can also try to find a cheap replacement watch to get the parts from.

• Clamp (Ronda calls it a bridle) Part Number: 3601.109
• Screw Part Number: 4000.250

These parts can be exchanged between Ronda 4000 and 5000 series calibers (ie: 4003, 4120, 4220, 5010, 5020, 5030, 5040, 5050, 5130 . A, B, C, D, etc) and possibly others.

You may also use part number X/14884 to find what you need.

Replacement Prices:

When buying from a watch parts supplier, the screw and clamp will likely be sold separately. You can expect to pay around $5 or 6 USD for each part. If you can buy several in bulk, it’s not a bad idea. The screws found in general screw kits generally won’t fit.

Ways to avoid the catapulting screw:

After you do enough battery changes on Ronda chronos, you will get the hang of it and the lost screws will only happen every 1/10 times instead of 10/10. Some tricks of the trade include using your glove or cot covered finger to hold the clamp down until you get the screw in placed and screwed in.

Another method that some choose is to use Rodico to hold everything in place while securing the screw.

Bonus: Another con of the Ronda quartz chronos is the need for the orangish/brown translucent insulator tab that goes under the battery cell. These sometimes get damaged from battery acid that leaks, or simply lost during the battery change. These also have a unique part number (3603.034), although you can sometimes cut your own from a larger piece of the material.