Seiko 6139-6002 Chronograph - A True Classic

Its always a pleasure to service a Seiko and this month was made extra special by servicing not one but two Seiko chronographs ( one being my own ). This watch came in for a long overdue service, being a watch thats been handed down the family line the owner wanted it running back in tip top condition.

The watch was running but the chronograph could not be stopped or reset, the date function had also completely ceased and timing was sketchy at best. The most common problems with this watch are often the most dreaded but fortunately the chronograph wheel was not in bad shape and the original winding gear for the inner bezel was still present and rust free.

Stuck in the mud...
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Due to the holow design of the pushers, years of gunk and sweat can build up inside and wreak all sorts of havoc with the chronograph mechanism. The combiniation of moist sweat, dirt, and body heat can casue the springs inside to rust and become rotted in, cleaning them is usually straight forward but on this occasion the spring is truly rusted in. With patient scratching away at the rust i manage to free the damaged spring and the case can be cleaned up. Its surprising sometimes just how much can get stuck in them pushers  ;(

The pushers now removed the casing parts are stored separately away from movement for their own cleaning, i clean casings with a different machine to prevent contamination of the movement. The front end is built up of several parts including bezel, glass, rubber gasket, inner bezel, bezel spring.
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​Movement Strip Down - Seiko 6139B 17 Jewel
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Below are the pictures ( may not be in order ) of the movement strip down. Fortunately the chronograph wheel was in good order and an expensive replacement would not have to be found, however other parts had started to suffer and they would have to be replaced.
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Movement Assembly & Adjustment
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With the movement clean and damaged parts swapped for new it was time to rebuild and adjust as required. >>
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Timing looking much better and with only a few adjustments she was purring away happily. Its important to note that setting the correct lift angle on the timegrapher is key to getting correct information on the watches condition ( Seiko 6139B / has a 54.5 Degree Lift Angle ). Unlike Swiss movements Seikos run slightly different and a amplitude of 180+ is considered healthy, this movement running at 222 on a half wind is more than enough for me.
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Casing & Bracelet
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With the movement running well it was time to turn my attention to cleaning up the casing and bracelet. The satin finish had taken a few knocks so a brief touch up and thorough clean should go a long way, along the way a little polish to finish the job. >>

Finished Watch
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Finishing a Seiko is always very satisfying and this one has been both a pain and pleasure to restore to good order. The reset is not always dead on but the watch now runs well, day & date set correctly, and importantly the chronograph can be started , stopped , and reset  ( albeit not dead on every time due to minor wear ). With watches of this age it is expected to have some flaws, without them they kinda loose some of their charm and character, luckily this has plenty >>