Seiko 7A38 - by the numbers

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Forum Home > Bend it, Mend it - Mods & Wreckers > An utterly perplexing metal blob on watch back.

Rob Benham
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Posts: 269

I purchased this a few days ago and it was declared as a no-go.  I was relieved to find a quite clean movement though one coil was open circuit.  Tedious, as it was for the second time in a month, one of the big ones where my last purchase batch is down to two small ones.  It seems that lot may be the last new ones I can lay hands on as I recal I had to have them sent to the US from the UK four years or so back.

This fault may be linked to an oddity on the case.

It was some time before I poked at a tiny blob on the back's edge.  It didn't budge.  I used one of my micro chisels made from a large sewing needle.  It still didn't budge.  Drag out the old Watson Scientific microscope. 

The two blobs, one about the volume of a large grain of sand, were near a gouge mark that was counter-intuitive.  i.e. as though someone slipped doing it up!  It may juat be coincidental. 

The connection between all this is the notion that someone may have taken extraordinary measures to open the case - perhaps using electrical power to induce heat.  I then wondered if the coil had induced current that fused it inside, as the usual damage was not evident.  I imagine the circuit will be history if that's the case. 

There is one other scenario that I can think of.  The metal has some impurities that have rusted, but the blob just seems too hard to be rust.  I'm at a loss. 

Despite being small, the blob would I'm sure irritate one's skin fairly quickly. 

Any thoughts?

March 23, 2018 at 9:07 PM Flag Quote & Reply

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