Service Eterna 520U

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The Eterna calibre 520 is a superb pre 1950’s movement and their last model featured modern shock protection. This watch is in decent condition, but in need of a service.

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The movement is in decent condition. (I have already replaced the barrel bush when I did my last 520).

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Here you can see the gear train with the train bridge removed.

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The click and click spring is fitted on the underside of the barrel bridge.

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Old mainspring.

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After cleaning the movement I fit the cap jewels to see that the movement moves freely. I like this version the best as it provides the best shock protection.

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Mainspring in the barrel.

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Gear train comes back in place.

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The crown wheel is fitted underneath it’s own bridge.

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The construction of this movement must have been expensive as it has 3 individual bridges and a separate escape wheel cock.

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Setting/winding mechanism back in place.

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Movement back together and ticking.

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Preforming well for a 60+ year old watch!

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I suspect the dial was restored a long time ago and still looks very nice.

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Someone fitted a tension ring crystal even though the watch should have a normal crystal.

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Movement back in the case looking good!

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For being a late 1940’s watch it has a rather large case diameter of 34.5mm w/o crown.

Eterna 520U

Super watch that would go well to most occasions:)

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6 Responses to Service Eterna 520U

  1. Gary says:

    Hi Mitka,
    Great walkthrough! Thank you for sharing. Question, did you have the case replated?
    Gary

    Like

  2. mitka88 says:

    Hi Garry,

    No need as it’s stainless steel. The discolouration on the case was grime that cleaned up:)

    Best regards,

    Mitka

    Like

  3. Dušan says:

    Hi Mitka,

    Great articles on your site. I wish you all the luck now that you are working independently.

    One question, how do you know this watch should have a crystal without a tension ring?

    Regards

    Like

    • mitka88 says:

      Hi Dušan,

      Thanks:)

      You can tell by the grove the crystal is fitted in. Tension ringed crystals have straight edges while the normal crystals have a slant grove.

      Best regards,

      Mitka

      Like

  4. David Webb says:

    Excellent site & information & first class work.

    Like

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