HEUER Chronosplit Repair and Modules

ESA 900.231 Module and Repair

The idea for the Rawsar H4 module came to me a couple of years ago when a customer asked me to repair a Heuer Verona.


The Verona exhibited the erratic behaviour I discussed on the last page. After a lot of searching and emails I did manage to find a NOS module to repair the watch but it struck me how difficult it was to source a good reliable replacement module.


I also have bought a fair few used ESA 900.231 (Chrono) and ESA  900.911 (Alarm) modules online and all of them have similar problems, time for a new module I thought.


The Rawsar H4 has taken me around a year to develop and get right as it is the smallest module I have designed and built and I thought the H3 was difficult !.


As per the original ESA Y2 900.231 movement the Rawsar H4 module drives both the LCD and Analogue parts of the host watch, it also functions in exactly the same way as the original except for 1 minor issue that the time colon does not flash and is permanently on in time mode. This was a deliberate move to save power much in the same way Ebauches SA did by only driving the Lavet stepper motor every 5 seconds.


Currently the Rawsar H4 module is undergoing battery consumption testing but will be ready for market very soon.


November 2020 Update


I am delighted to announce that after extensive testing that I can now offer repairs to watches based on the ESA 900.231 module using my H4 module. I have had a lot of interest on supplying modules but currently I am only offering repairs to your whole watch only using my H4 module. By repairing your whole watch I can ensure that the H4 module both fits and functions correctly, this also minimises problems. The cost of this service is $450 Australian Dollars plus postage.


In the longer term I may offer a module repair service, module exchange service and possibly  direct sales of H4 modules, however I wish to focus on watch repairs first.


The Rawsar H4 repairs should suit the following watches:



Heuer MEMPHIS 371.303

Heuer Verona 371.213*

Heuer Verona 371.215*

Heuer Carrera Twin 371.253

Heuer Carrera Twin 371.255

Heuer Diver 980.024

Heuer Diver 980.027


*Heuer also produced an alarm version of the Verona.


Breitling Navitimer 2100  Pluton

Breitling Navitimer 2300 Jupiter

Breitling Navitimer 2400 Cosmos


Chronosport UDT Sea Quartz 8109

Scubapro 200




If you are interested in a H4 conversion please email support@rawsar.com

Fig 1. The Rawsar H4 module.

Fig 2. A repaired Breitling Navitimer 2300 utilising the Rawsar H4 module.

A demonstration video of the Rawsar H4 repair module: