For professional watchmakers. Reference only.

This guide is provided as a technical reference for qualified watchmakers servicing Brew chronograph watches. It is not intended as do-it-yourself instructions. Opening the caseback or servicing the movement should only be performed by a professional watchmaker.

Damage caused by mishandling, tampering or unauthorized repairs is not covered under the Brew warranty. If your watch is under warranty or needs service, please contact us first and we'll take care of it.

Movement and battery

  • Movement: Seiko (TMI) VK64 + VK68 meca-quartz chronographs 
  • Battery for TMI VK64 and VK68 movements: SR936SW also sold as 394 (silver oxide).
  • Type: 1.55 V silver oxide Expected life is 3–4 years depending on climate and use.
  • Tools: Flat-heard watch screwdriver, non-conductive tweezers for battery handling, conductive tweezers for the circuit reset.

Diagram

Diagram from the TMI VK series technical guide. 

Battery replacement procedure

  1. Open the caseback. Keep the caseback gasket clean and in place.
  2. Remove the old battery. Release the hook of the battery clamp (switch spring) and lift the battery out.
  3. Install the new SR936SW (394) battery.
  4. Reset the circuit (required). With conductive tweezers, touch the AC terminal of the circuit block and the switch spring at the same time, as shown in the diagram. Without this step the movement may not start, even with a new battery.
  5. Set the time. Pull the crown to the second position, set the hands, then push the crown fully back in. The movement will not run with the crown pulled out.
  6. Confirm operation. Check that the small seconds hand is running. The chronograph hands do not need to be re-zeroed after a battery change.
  7. Close the caseback. Confirm the gasket is seated evenly before tightening to maintain the 5 ATM water-resistance rating.

If the movement does not start

  • Confirm the battery is new, at full voltage, and an SR936SW (394).
  • Check that the battery clamp hook is caught on the main plate.
  • Repeat the circuit reset in step 4.
  • If it still won't start, the customer can contact Brew for service.