Removing and replacing inexpensive Timex crystal

[xyzzy]

I'm trying fix to an inexpensive quartz Timex from the probably the late 80s.  I realize that it's not worth repairing, nor even meant to be, but nonetheless I'd like to try.

I haven't found any serious problems with the movement so far.  Coil has 1kΩ resistance, no corrosion on circuit board, rotor appears undamaged.

But it's a front-loader, so the crystal needs to come off to clean it and to get the dial side of the movement.  The plastic crystal has a lot of crazing in it and I don't think it was meant to be removed.  So I think there's a significant chance it won't survive removal, if I can even get it off with a crystal lift.

Does anyone recognize the way this crystal is attached?  How about what might be a suitable replacement?

It's slightly domed, with what looks like a large bevel on the edge that become vertical sides.  The acrylic looks thick.  There is no step.  The case is cast and while it has the form of an exterior bezel, I am quite sure this is part of the same casting as the rest of the case.  There is no exterior removable bezel.

Inside there looks like some kind of interior bezel, from the dial to the under the top of the case.  It looks like the top of the this bezel is smaller than the open in the case and has a flat top, which the crystal might be resting on.

The sides looked like maybe G-S AT would work, but I think these have a flat top, not domed.  And I really don't think there is an interior tension ring.  Perhaps Sternkreuz CO would work?

Here's some picture.   I put some think masking tape on the crystal so I could get a photo where the profile of the edge was actually visible.

Shape of the dome.  What looks like it might be an exterior bezel is quite clearly part of the case under magnification.

Looking at the inside of the watch bezel, crystal not really had to see, but I think the bottom rests on that lower ledge, which I think is a removable bezel ring, while the part above the ledge, with the rounded side, is part of the cast casting.

One asks, what movement or case is this?  I don't know, I can find anything to ID it!  I think the 57 on the case back is a Sep 1989 date code.

The front has no writing beyond Timex Quarts.

Nothing for the movement.  Timex, Philippines, Unadjusted, NO (0) Jewels.

 

There is a code in the battery holder, but I think it's just another date code, though it doesn't follow the format I found online.

[Randy55]

I'm thinking that a G_S PK Lo-dome may work,.but you will have to get this one off to verify the real profile

I would hazard to guess that it's cemented on with a typical crystal cement. Getting it off from the front may be a chore....

 

[JerseyMo]

fit the crystal and there will be a dial code printed just below the 6 hour marker. 

[xyzzy]

Wouldn't a G-S PK have a step and then a flange that's designed to snap into an undercut in the bezel?  This crystal really doesn't look like there's a step, nor a flange that snaps into an undercut.  It's dome, bevel, then vertical sides and that's it.

The dial code is hidden under the interior bezel, or rehaut?  The dilemma here is that is I will probably destroy the crystal trying to remove it, but must do so to find out if it can be replaced.  It would be much better to know before destroying it.

I haven't seen a Sternkreuz CO "Koncav" crystal and can't find any decent pictures of the crystal itself.  It looks like it has a low dome from the little picture in the catalog.  Does it?  Or is it flat?

[JerseyMo]

why would the crystal get destroyed?  

[xyzzy]

A few reasons I expect removal to end poorly for the crystal.

As can be seen in one of the photos, the vertical sides of the crystal above the face of the watch are short.  There is little for the crystal lift to grab on to.

I think it's glued in, so the glue will have to be broken free to remove it.

The face of the crystal is crazed.  There are many cracks inside the acrylic.  They are not scratches on the surface.   Some of them can be seen in the picture of the watch face, to the right and below the Timex logo.  The short horizontal scratches.  These aren't on the upper or lower surface but are cracks inside the acrylic.  You can't really see the depth in the photo, but when moving the crystal around while looking at it in a stereo microscope, it's clear.

I think the stress of trying to grab it and break the glue free will be too much for the crazed acrylic to take.

 

Edited November 9, 2021 by xyzzy

[JerseyMo]

ok if it is the original Timex crystal on there it should not be glued in. Timex used a similar crystal on many of its watches from that era.  I use a Timex crystal wrench to remove them.  they are quite thick and can take a good amount of pressure.   I typical replacement with low dome crystals from other model Timex. 

I give you credit for working on the watch as it as little to know $ value. But I know the feeling of wanting to get it done having just spent many hours messing with a recent lot of quartz watches that are worth less than the batteries in them.

best of luck with the repair

[xyzzy]

You were right, there was no glue.  Typical lip that fits into an undercut in the case.  Just could not see it at all through the crystal.

The crystal is indeed quite thick.  Despite years of practice opening jars for my wife, I needed to put on some rubber gloves to get better grip on the crystal lift to tighten it enough to compress the crystal to get it off.

There was a number on the edge of the dial, hidden
under the rehaut, 4403760288.

Crystal is 30 mm on the flat part (where the lift is gripping), 30.4 including the lip.  It's about 1.6 mm thick and solid, double domed, but the inside dome might be flatter than the outside.

Edited November 16, 2021 by xyzzy

[JerseyMo]

the date code on the back of the case would translate to sept 1989.  the dial code 4403760288 breaks down to model, movement, year.  so the year printed on dial is 1988.  Production years could have certainly overlapped.

[xyzzy]

I think I found the culprit. Something stuck the calendar and it looks like the hour wheel has ground down the plastic wheel, central in the below photo, that interfaces to the date change.

There's a residue of some sort on the wheel, sort of a crusty yellow.  You can see it intermixed with ground up teeth on the top, but there is more on the undamaged teeth on the bottom side.  Not sure if it's dried grease or some kind of battery leakage or other corrosion product.  I didn't think the battery had leaked, the battery holder is perfectly clean as one can see in the photo in the 1st post, but now I'm not so sure.

Three of the five screws holding the movement together were black, while two otherwise identical screws were typical bright steel.  It did not look like rust.  Black not red.  Tops still flat, slot still formed correctly, not the blob a heavily rusted screw turns into due the massive increase in volume of the iron oxide.  And uniformly black, tops, under the head, the complete threads at the way to the tip, etc. on all three screws.  While the two other screws were perfect.

It looked like someone had carefully applied chemical gun bluing to the screw, the kind that gives a very dark blue that's practical black.  I did that to the screws in my house's vintage mortise locks when I refurbished them, very similar look.

[xyzzy]

I think I was wrong about the screws being bright steel.  They've got a bit of texture to them.  I think they are plated.

Also the three black screws are slightly different than the two bright ones.  The black ones have about 8.5 threads while the bright are slightly shorter at 7 threads.

.

Cleaning the black screws in naphtha and scraping at the top with a pegwood scraped off some yellow residue.  Alkaline battery residue?  So, I put them in some vinegar in the ultrasonic for a few minutes, then cleaned with water and soap.  Now they look copper!  Except they aren't copper because A) they are magnetic and B) copper screws??

So, I think plated.  It's copper strike with something bright over it.  I think this is done to plate nickel onto zinc alloys?

There was also some kind of liquid residue on the plastic around the posts the screws were in.  It's not oil as there are no moving parts anywhere near here.  I don't think they used oil either, as I didn't see any on the parts that do move.