Casio MW-58 (1319 Module)

[BobKay]

I was recently given a vintage Casio MW-58 (1319 module) analog watch. This has the illuminated face plate. The batteries have never been replaced - I know this to be true as it was my son's. I have a few questions.

1. Do I slide the batteries out, or is there some way to release them?

2. Referring to the attached photo, there is a blue plastic piece of film which is acting as an insulator. That makes no sense to me. Must I reinstall it with the new batteries, or was this an error made during manufacturing?

3. Can anyone suggest a current battery part number?

Many thanks

Bob

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[watchweasol]

Hi Bob  The battry is a sr621sw   (364)   (silver oxide0     The numbers are etched on the the cct board..  The watch its self looks rather grubby   and would benifit from a clean

[BobKay]

No argument about the cleaning, but the real uncertainty is how to safely remove the cells and what is that blue plastic insulator used for? It electrically isolates the battery.

Edited September 30, 2021 by BobKay

[watchweasol]

Firstly  has it ever worked before you took the back off,  If so the refit the batteries as is, the dual battry arangment is because of the light feature as it soaks up power. There is a screw which appears to hold the cct board down near the battry remove it and see if the contact assy slides out to allow easy removal. I have had a check for a tech sheet  but as yet none found.  one of our members Andyhull works on electronic/digital watches he may have the direct answer.

[BobKay]

It worked fine for many years. I'm sure its just a matter of replacing the two cells. Casio just responded saying they dont offer any technical assistance to the end user. I would agree on installing the new cells just as the original cells are, but I do believe that the blue insulating material in not suppose to be there. Hopefully another member will join the discussion. I truly appreciate the prompt response!

[watchweasol]

It certainly is odd they both loo as though they are separate , one runs the watch and one runs the backlight, remiove the one without the insulator and replace it,      see what happens. or remove both batteries  and post a picture of the watch back again so we can acertain If i am correct in thinking  they are seoarate in operation.

[Marc]

 

2 hours ago, BobKay said:

It electrically isolates the battery.

I can't offer any suggestion as to why the blue film is there, but it doesn't isolate the battery. The battery positive contact comprises the back and sides of the battery case, there is a tab in the side of the battery well which makes the electrical contact with the side of the battery, and of course a pad in the base of the well for the negative connection. Although it does look as if the spring tab that sits on top of the battery provides the positive conection, I think it is simply to keep the battery secure.

From the shape of the sprung retaining tab I reckon that the battery is intended to slide out. An SR621 is not a thick battery so I would be inclined to use a screw driver to gently lift up the free edge of the battery whilst at the same time pushing the opposite edge of the battery through the slot in the retaining tab. Once out the new battery is simply slipped in under the raised edge of the retainer. Just be careful not to slip and gouge anything though.

Is there a piezo sounder element cemented into the case back? If so then it's possible that the blue film is to prevent an electrical contact between the battery and the piezo.

[LittleWatchShop]

3 hours ago, BobKay said:

but I do believe that the blue insulating material in not suppose to be there

I think it should remain.  At some point, it was working and some time later (long after the batteries died) it stopped working.  The insulator was there during both periods.  I believe the clip holding the battery under the insulator is not electrically the same (i.e., same node) as the positive terminal for that battery.  This easily verified using a meter (continuity) once you remove both batteries.

Regarding moving the batteries...I think you just lift the clip and nudge them out.  I suggest installing the insulated one first and then the other one.  I would hazard a guess that the insulator is stuck on the battery to make this installation fool proof.

[LittleWatchShop]

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