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 is protected with a sealed plastic cover. Please see Fig. 2


The ESA 900.231 module runs both the analogue and LCD part 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 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
  • Crashing/resetting


The above problems seem only to be caused by age or possibly ESD problems where the module has been zapped due to miss handling CMOS devices which this is one.


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.



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.