Kronos British SBS Satin 200M Military Diver Watch Modification (Part 1)

This is my modification of the Kronos British SBS Satin 200M Military Watch (no date, orange second hand) Part 1. Why? We will see later. I got this watch very cheap from the Internet (used). I will not go into a review of this watch at this time as this is about my modification to the watch. However the basic specifications:

Case: stainless steel

Size: diameter 42 mm, height 13 mm, lug width 20 mm

Crystal: Mineral

Water resistance: 20 ATM

Photographs: Military Watches Mall

One modification carried out by the previous owner was to replace the spring bars with thicker Seiko spring bars. I had a look at the spring bars and they are very solid and secured on the watch. I thank the previous owner. It does give me some comfort when wearing the watch with the 1 piece Mil spec strap.

This was is fitted with the ETA 804.114 quartz movement. I understand this is the basic ETA quartz movement.

Basic specifications:

10.5 ligne, height 3.40 mm

0 jewels

3 hands (120/70/20)

Date with quick set (unused as this is the non date version of the watch)

The watch with the case back removed. You can see the movement in the watch and the white movement holder. The design of the movement holder is interesting as there is a tab to hold the battery. The movement is ETA, but China movement with Swiss parts.

Why change the movement? Well I kind of like the quartz movement that drives the British military issued CWC and Precista. Since this watch is a homage to the British RN Diver watch, why not fit it out with the same movement. Additionally I like the fact that there are 7 jewels in the CWC/ Precista movement. The problem is that the CWC and Precista is fitted with the ETA 955.112 movement which is 11.5 ligne. Finally found that ETA has another movement in the 955 series, the ETA 955.412 movement. It has the same diameter as the ETA 804. However it is thinner, but should not pose a problem as I can fit it with a thicker battery.

The movement, ETA 955.412. Note the hour wheel on the outside of the movement case (about the 3 o'clock position).

The bottom plate.

The top plate.

Now that I have the replacement movement, the modification can proceed. First, remove the battery, then the crown. The out comes the movement and dial. Note that dial is held in position via friction to the movement. You can see the dial feet at the 6 o'clock position.

The case and the case back.

Other parts of the movement. At the 1 o'clock position, we can see the stem. The longer stem is from the new movement. We will need to trim the stem down to the original stem (shorter one). We can see the crown at the 4 o'clock position. It is of the screw down design. We can see the battery and the white movement holder. The gold wheel is the hour wheel of the new movement and the black crown is also from the new movement. It also acts to protect the tip of the stem.

Mount the movement on the movement holder to facilitate the removal of the hands.

Don't forget to protect the dial.

The hands, removed from the movement. The hand size: 120/70/20.

The dial side of the ETA 804 movement. Notice that it comes with the date wheel. The hour wheel seems integral with the movement.

The dial.

Next is to install the dial to the movement. The ETA 955 uses the modern dial fastener. You can see this at the 5 o'clock position. The fastener will swing into position and cut into the dial feet and hold it in position. The hole you see at the 9 0'clock position is the case screw hole. It is to hold the movement to the case. We will not be using this as we will be using the white plastic movement holder.

Now to refit the hands. The new movement and dial on the movement holder. Don't forget to protect the dial.

The hands installed. Reinstall the stem to check that the hands do not hit each other or bind. I also refit the battery to check that the second hand does not bind and can do 1 full rotation.

Remove the stem and refit the movement into the case.

It fits perfectly. But something is not right. The movement holder. The tab is not over the battery slot. Another view.

A small modification to the movement holder and problem solved. Now the tab is over the battery slot.

This is where the modification comes to a halt. Why? Well I decided to inspect the case. I found the internal thread of the crown slightly damaged. This is not good, as this may mean that the stem tube on the case may be damaged. On closer inspection, I found that the stem tube is cracked. This is not good at all. Well, it is off to my friendly neighbourhood watchmaker and see what can be done. Stay tuned for further updates.