HEUER Chronosplit Repair and Modules

ESA 900.231 Module and Repair

Overall, the ESA Y2 900.231 module is made to a high standard both mechanically and electrically. It is also worth mentioning that unlike the previous Heuer LCD watches like the Chronosplit and the Manhattan the delicate electronics are protected with a sealed plastic cover. Please see Fig. 2


The ESA 900.231 module runs both the analogue and LCD parts of the watch in a single module. The analogue hands are driven by a Lavet-style motor that is pulsed every 5 seconds. The first 5-second pulse is positive driving the motor 180 degrees, the 2nd five-second pulse is negative driving the motor a full revolution. This I believe was designed to save battery power and is also replicated in the Rawsar H4 module which is discussed on the next page


The LCD display consists of a very small LCD panel with 4 x 7 segments and 2 colons which indicates the operational mode.




The biggest problem with these modules is erratic behaviour, especially with the LCD display and push buttons. This manifests itself as:


Flickering segments

Missing segments

Unresponsive buttons



The above problems seem only to be caused by age or possibly ESD problems where the module has been zapped due to miss handling.


In my experience, the analogue driving part of the module seems to be more resistant to faults however they also do fail from time to time, more details on typical faults, things to look out for and pricing can be found further down this page.


Fig1 - Original ESA Y2 900.231 Module front and rear view

Fig 2 - Integrated circuit hidden under display. Left sealed cover, right cover removed exposing IC and bonds.

Fig 3 - Clean wire bonds, faulty IC.


General Problems


Here are some of the issues that I have learnt along the way whilst repairing watches based on the ESA 900.231 module.


1 - Pushers

To carry out a successful repair both your left and right pushers need to work without sticking or jamming, If your pushers get stuck or jammed the H4 module will draw excessive power and drain the batteries quickly.

I don’t have the tools or spares to repair sticky or jammed pushers but sometimes I can free them up by lubricating them.


Please check your pushers simply by pushing them and making sure they work smoothly and return without jamming.


2 - Spacer Ring


In some of the larger ESA 900-231 based watches, there is a plastic spacer ring that holds the ESA 900-231 module into place. The ring also has special plastic “fingers” that assist the pushers by transferring the pressure to the electrical contacts on the H4/ESA module.

Ideally, these spacer rings need to be intact and undamaged to allow for the pushers to function correctly.


These spacer rings often become fragile due to their age and I don’t hold any spares.


I have developed several ways to repair the spacer ring and costs vary depending on how much time and effort I have to put in.


My advice is not to touch the spacer ring as they can be brittle and easily damage


3 - Dirty or damaged ESA mechanism


Sometimes the mechanical part of your ESA 900-231 module can become dirty, worn or broken. I hold spares and can repair them but this adds time and cost.


A couple of checks can be made before sending your watch to me.


a)If the analogue part of your watch works does it keep good time? If the analogue part runs but loses time it could be that the mechanism is dirty. This will need a complete strip-down of the watch and ESA module followed by a clean and oil.


b)Another recommended check that is advisable to try is the analogue time setting. Pull out the setting crown (unscrew first on some models) and carefully twist it clockwise and ensure the hands move and set properly.

Repeat this in an anticlockwise direction, the hands should move smoothly. If you notice clicking stop as the mechanism is either worn, broken or dirty and will need stripping down and cleaning.


If your watch has either of these issues I recommend that the mechanism is stripped down and cleaned, oiled and reassembled. The cost for this service is $200 AUD



 4- Non-functioning analogue time


The Rawsar H4 module like the original ESA 900-231 module drives the analogue part of the watch however it is reliant on a working and clean mechanism (see above) and a coil that drives the motor. Sometimes these coils break or are damaged by previous repair attempts as they are very fragile and easily damaged.

I can supply and fit an original  ESA coil for $100 AUD if required.



5 - LCD Display


In most cases, your LCD display should be OK and will be reused. I remove the display clean it and fit new conductive zebra strips this is included in the AUD 475 price. However, sometimes the LCD display can be affected by the following issues:


 a)Completely dead, in this case, I will have to fit a reclaimed and tested ESA LCD display. The cost for this is $150 AUD


 b)Faded or weak display. This can sometimes be rectified by replacing the front and rear LCD polarisers. Cost $50AUD


c)Temperature fade where the display will work in a cool environment but fade or die in warm or hot environments. The only solution is to replace the display the cost $150 AUD.


If your LCD display is working (even partially) please send some pictures to me.



I'm currently working on providing new Rawsar LCD panels as I have done for my H1, H2 and H3 modules but in the meantime, I have a stock of original ESA LCD panels


 6 -Weak screw-down crown


Some of the ESA 900-231 based watches incorporate a screw-down crown.

I have seen examples of these watches where you can unscrew the crown and set the watch OK but you cannot return the watch to normal time mode because the spring in the crown is too weak to overcome the spring in the ESA module mechanism.


Please check your watch can set the time and return to time mode. If the watch is not running sometimes difficult to do but you should feel and hear a click and the crown will release from time set mode and then just spin freely.



7 - Spare Parts


I only carry spares for the original ESA 900-231 module as mentioned I do not have spare parts for your watch.

I’m sorry I don’t provide spares or modules, I use the spares I have to perform repairs.