HEUER Chronosplit Modules and Repairs

This page is dedicated to the internals of the Heuer Calibre 102 Chronosplit and what goes wrong.


As explained in the previous page Heuer leveraged 70s LSI technology and "improved" the electronics in the Chronosplit with a reduced IC count, lower power consumption and a faster chronograph. On the face of it this was a logical and advanced step, however as you will discover its Achilles heel is the "open" construction of the integrated circuits.


The next page covers the Rawsar H1 Repair module a reliable repair option for the ill-fated Calibre 102 watch module.



Fig 1. Front and rear view of a rare fully original working Calibre 102 Chronosplit module:

Original Chronosplit LCD LCD module - Front
Original Chronosplit LCD LCD module - Back

Within the Calibre 102 Chronosplit module there lies a single circuit board that hosts three very delicate integrated circuits, two ICs are open the third is encapsulated in black epoxy resin. The wire bonds that attached the ICs to the substrate are thinner and more fragile than human hair, as such, they are extremely delicate and fail in several ways.

Fig 1. Rear and front view of the Chronosplit PCB. Note the very delicate exposed ICs.

Original Chronosplit LCD LCD module - Opened back
Original Chronosplit LCD LCD module - Opened front

Fully functional Calibre 102 modules are very rare as the majority have failed during their 40+ year lifespan, this has given the watch the rather unflattering name "Chronosplut" amongst enthusiasts and collectors.


Module failure occurs as a indirect result of very poor internal design. The design relies on bare exposed integrated circuits connected to the substrate of the PCB with very fine and delicate wires. As a result, the exposed wire bonds and ICs have very little protection from external influences such as leaking battery acid, stray fingers and foreign objects that can cause short circuits.


The age of the module also plays a significant part in its demise, as Heuer used conductive epoxy to adhere the ICs to the substrate. I have seen many instances where the very old epoxy glue fails causing IC lift or complete shear, this can be exacerbated by mechanical shock.


To add to the problems the old first-generation LCD displays tend to completely fail or "bleed". Dead displays typically in most cases will go completely black or show black streaks when they fail. I however have developed Rawsar replacement LCD displays which are a direct drop-in replacement for the original.


Please see the next sections for LCD Chronosplit repair or where a repair is not possible a Rawsar H1 module.

The pictures below depict typical Calibre 100 Chronosplit module failure scenarios including battery corrosion, short circuits, wire-bond damage & IC lift due to silver epoxy failure.

Chronosplit LCD LCD Corrosion
Chronosplit LCD LCD Short circuit
Chronosplit LCD LCD IC lift
Chronosplit LCD LCD IC loss
Chronosplit LCD LCD - Wire bond trauma
Chronosplit dead broken LCD

For advice or enquiries please send an email to support@rawsar.com