restoring unknow led watch

[albertofenini]

ciao a tutti,
I have purchased this watch because I liked the shape of the case

00040.jpg

It was described as non working, and it is non working
However, the module is extremely clean, and I was expecting to find a fix.

00038.jpg

00037.jpg

I have noticed is that the left battery contact goes nowhere.

I mean, the smaller gold sopot on the right is where the negative side of the battery goes
and is connected to the time adjusting trimmer, then there is a metal clip on the watch back cover (not shown)
that shorten together the two LR-44 and the positive side of the second LR-44 battery goes over the big golden
spot on the left side of the module.

However, apparently it goes nowehere from there.

Could it possibly be a multi layer pcb ??

Thanks for any help or hint
Alberto

[richard_uk]

Maybe connected through the pcb to one of the tracks on the front?

[albertofenini]

That could be the case of a multi layer pcb, let's hope some one in the forum knows the module

thanks Alberto

[Old Tom]

The Exonix modules are double sided but instead of using conventional through hole plating to connect the sides they used tiny Gold pins which fit flush to the board and can be quite hard to see. I have had success on three occasions & getting these to work by replacing the crystal with an oscillator chip.

[albertofenini]

Thank you very much,

I'll post more pictures of the module, I was expecting to see some clips connecting
the two sides, but apparently there are none, I have looked around the side of
the module as well.

How can I check if those pins are present ??

The positive contact looks absolutely "isolated" from the the rest of the board so my
guess is the the board itself is not getting any power.

thanks again Alberto

[albertofenini]

Guys, I wanted to get rid of battery supply, being the module out of the case this was making hard
to make any test.
So I have soldered to thin wires and connected them to 3.0V DC external power supply.
Then, playing with a tweezer I have found out that if I short-circuit the gold terminal
(lower side of the module in previous pictures)with one
of the three soldered contacts, the watch lights up, it also enter in set mode, shows the calendar,
I cannot say it works, but at least is not dead or missing segments.

00069.jpg

00070.jpg

However, when the module is put back in the plastic shell and then in the metal case, nothing happen.
The front gold contact I'm touching with the tweezer in the pictures is normally under the top half of the
plastic shell that contain the module.

What can I do ? What is missing to transfer the battery power to the module ? Is still a Quartz problem ?

If this would be the case, any quartz from a led watch will do ??

Also, look at this picture :

00041.jpg

Under the red circled hole, there is a gold contact that goes nowhere,
so I have tried to insert a small spring, like those that are used to connect the alarm piezo to the module,
still nothing ...

Please, any help will be very welcome !
thanks again Alberto

[azimuth_pl]

hi Alberto,
please try again with a longer spring that needs to connect the board to the caseback.
the same approach was used the Frontier/Omega modules:

[albertofenini]

Thank you very much for the suggestion, I have used a spring like this :

00106.jpg

also I have used a fresh set of batteries, but nothing ....
It must be considered that the circuit point that light up the watch is this on the front :(the one circled in red)

00107.jpg

while the spring touches this one on the back :

00108.jpg

I have checked with a ohm meter that the two are not interconnected in any way.
Waht can I possibly test ?
thanks again, Alberto

[azimuth_pl]

Just a guess here as I have not seen this module before.
The point on the back goes all the way to edge of the board and the same thing is with the point on the front.
Perhaps these were once connected and then the spring on the back would work.
Give it a try and if not you can still use the spring and solder it to the point on the front but insulate it from the point on the back.

btw. why so much solder on the battery pads?

[albertofenini]

Hi there,
soldering has been done because during the previous tests I have used an external 3.0 V power supply
rather than batteries. I have soldered two thin wires (see previuos pictures) and then connected the
module to power.

This has allowed me to play with a twezeer on the module out of the protective shell and out of the case.

Last night, in order to test the spring solution I have de-soldered the wires and cleaned (a little) the
soldering, enoought to not break the module for excessive pressure due to the soldering material under
the batteries.

I also have thought of something going aroundthe module in order to connect the front and
the back side, but it also must be said that before I did any test, the module side and traces where
perfectly clean, with no sign at all of springs, connectors, enything, it was almost immaculate.

Also, it's true that playing with the twezeer I have been able to get the module on, but it must be said that
connecting the trace with the three buttons produces a weird behaviour, for instance I have never been able to see
the seconds running, while I have been able to see hours and minutes (still on 1:1) and the date.

Have you have ever seen this module ?
thanks again Alberto

[azimuth_pl]

I've never seen this one so can't share any hints.
it's a ceramic multi-layer board so it might be a broken trace someplace beneath and thus unrepairable.

whenever you want to solder wires to the battery pads you'd better do it on the trace leading to the pad with positive polarity and on the very edge of the negative pad.
when you place a battery negative side down it never touched the entire surface of the pad so you can leave solder on the edge for a future attempt with wires.

[retroleds]

Alberto,
I am very familiar with that module - I have 2 or 3 on e my site with that one. It is usually a stopwatch of the left side contact.

You do not need the spring - it was never made with one. It is through-board construction - the contact you are touching on the front IS supposed to make contact, through the board, to the one on the back. I don't consider that multi-layer, just thru-board. The hole in the plastic was for testing purposes at the factory when assembled, many modules have these types of ports. So, you are thinking - how would you do that stuff from below? * I have a simular little "jig" for Frontiers, this one is just for generic stuff and ladies movements which always have the batteries closed together due to size. It may look crude, but it works great. Get creative (hint - springbars are your friend if you want to build a Frontier tester.

*Oy vay, I have reached the limit for board attachments, so I cannot show you this. WTF?
Sorry, the board attachment quota has been reached.

azimuth's suggest has a serious flaw - the negative side of a button cell has the positive charge right there at the edge of the negative side - you could easily short a battery. If you don't know, they make a nice pop if shorted for too long - not qite an explosion, but close. Other options I would show if I could upload - you can take a flat-jawed clip, bend one jaw so it is a tooth/fang for contact...cover the other jaw with some plastic so it doesn't short the traces on the front side and you have a friend for doing single side contact.

I wish you luck with this...

[bucko170]

.......*Oy vay, I have reached the limit for board attachments, so I cannot show you this.

This problem has previously occurred when photo's are added as attachments, you could try posting them via 'imageshack' or 'photobucket' or failing that send them to me and I will post them for you.

[retroleds]

That is a temporary fix - imageshack & pohotobucket don't keep them up forever. Server space is cheap these days.

Anyway....

Alberto,
Find a cheap toy or something that used a few AA or AAA batteries. Rip out the contacts that are spring and glue down to something with them not touching - now you have something to hook your power too and you can press a module or circuit board against the springs with one hand, leaving you a hand free for your 1.5v common(positive) from your power source/battery pack. This would be so much easier with pictures.

Fine - here it is over on this new digital watch forum- visit, there is no limit on attachments. And great looking user gallery..
http://www.thedigitalwatch.com/forum/viewtopic.php?f=19&t=38

[azimuth_pl]

...azimuth's suggest has a serious flaw - the negative side of a button cell has the positive charge right there at the edge of the negative side - you could easily short a battery....

What I had in mind is to leave a small point of solder on the edge of the pad, not a big blob. Also the surface of the pad is in many cases slightly bigger than the diameter of the battery so you should have not have any shorts.

[retroleds]

...azimuth's suggest has a serious flaw - the negative side of a button cell has the positive charge right there at the edge of the negative side - you could easily short a battery....

What I had in mind is to leave a small point of solder on the edge of the pad, not a big blob. Also the surface of the pad is in many cases slightly bigger than the diameter of the battery so you should have not have any shorts.

Still not a great idea, imo. The negative pads are usually slightly smaller than the diameter, only the positive pad is same or bigger. Considering the drop/distance from the negative terminal on the battery to the edge of the positive casing is .5mm or less(depending on manufacturer) a non-permanent solution is much safer. And the smallest blob could stop one from putting the back half of the plastic chassis back down neatly. I'm into neatly done.