Service: Seiko 3703-8000T / calibre EL 370

IMG_3731I have a soft spot for transistorized electronic watches so I could not resist this super cool Seiko EL 370.

The watch is running but the date does not change as it should.


IMG_3732Lovely looking movement.IMG_3734Movement out of the case.IMG_4724I start by removing the electronic unit very carefully as I do not want to damage the coil.IMG_3738Underneath the electronic unit you can see the hacking lever.IMG_3740To prevent backlash in the movement there is a tension spring that engages with the escape wheel.IMG_3741Removing the train bridge reveals the gear train.IMG_3744I now turn the movement over to start on the date and setting mechanism.IMG_3746I remove the day date spring revealing the date mechanism.IMG_3749Removing the plate for the date mechanism you finally get to the setting mechanism.IMG_4715The parts have been cleaned and the movement is ready to be put back together.IMG_4716I start by putting the balance jewels back in place.IMG_4718I turn the movement around and fit the center wheel.IMG_4720I then put the setting mechanism back in place – notice the long spring that provides tension for the date quick set. The plate for the date is also back in place.IMG_4721I now put the gear train back in place.IMG_4722The pallet has a little magnet attached to it. This cool feature is to create draw towards the banking pins that are made out of metal.IMG_4723Here you can see the recoil spring engage on the finely cut wheels on the escape wheel.IMG_4725The balance is put back in place.IMG_4728The day disk should be riveted onto the star wheel that engages with the spring, but it is loose and causes the disk to move out of place every time the date changes. I do not want to try and re rivet this, as the disk is very thin and delicate. I align the date correctly and use s small amount of super glue to fix the disk onto the star wheel.IMG_4729The movement goes back in the case and is looking good.IMG_5094I made a little isolation cap so the battery fits a little bit more snugly, I suspect it should have had one and that it is missing.IMG_4730I really like the dial design of this watch.IMG_5090The case diameter is a little large for my wrist, but with a leather strap and the hidden crown it just about makes it wearable;)

11 thoughts on “Service: Seiko 3703-8000T / calibre EL 370

  1. I found the exact same watch at a market earlier this year.
    Dates to 1972.
    The movement is quite complex – it has 16 jewels.
    Very expensive when new, but of course outdated by quartz.
    Mine shows good accuracy on a timegrapgher, but stops after a few hours.
    I guess after 43 years it’s time for a service..

  2. Your full of surprises aren’t you.
    Didn’t even realise / know that Seiko had got involved with Electronic watch’s.
    You learn something every day don’t you.
    Luv the simplicity and colour of the dial and the movement looks very presentable.
    If its doesn’t fit your wrist , it will fit mine I’m sure.
    Carry on the the good work .
    Barry.

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