What does it mean...

[Sully008]

when the display slowly fades away when I check the time? I wore my Sunwatch to work yesterday, and noticed that it wouldn't show the time. So I went to a window to charge the batteries, and it would light up, but not nearly as bright as it usually did. I got home and let it sit for several hours under a light and it did the same thing. It would light up dim and fade away.

I guess it could be one of two things:

1. The solar cell has gone for a walk.
2. The batteries are no longer holding a charge.

Both possiblilities would be really strange since both the SC and batteries are new. I guess I'm going to have to open the module up again...

[clockace]

mike, something could be draining the cells prematurely. peter

[Sully008]

Any ideas on what it could be, Peter? I'm not sure what it could be, the display is off, maybe it's a short somewhere?

mike, something could be draining the cells prematurely. peter

[clockace]

mike, not being that familiar with the sunwatch circuitry, i could only guess, but was it working well before you closed it up? on the ones i have going i only have used scotch tape up to now to close them to make sure everything is ok. they are easier to reopen that way. i had one that didn't have enough clearance for the cells and it put too much pressure on the pc board. it just stopped everything in that case. it could be that the sc connections are not good and the cells are not getting a full charge. i have always checked mine after a lengthy charge right at the cells to see if they have at least 2.6v. i have 2 modules that i have running well on the v40's. 1 because i ran out of v80's and the other because i used the black bottom from my sunwatch. i gutted it and it fits nicely but there is no room for the v80's. anyway i think on yours i would reopen it and check the sc connections and the cell wires to make sure the wires are making good connection with the tabs where you soldered them. as delicate as the mkIII/IV's are i think i am going to stick with the I's/II's. i have had really good results from the ones i have worked on. hope you find your problem. maybe one of the tabs is shorting out on the backside of the display. it sure sounds like something is draining them. best wishes, peter

[Sully008]

Well, I took apart the module tonight. Measured the voltage @ the cells. ~2.1v. Hmmm. Checked the voltage right @ the solar cell. ~2.1v. That's not good. Hooked up a pair of AAs to the module and voila! The module lit up nice and bright. I guess the solar cell went kaput and is only outputting 2.1v to the batteries.

Not sure why that would happen, unless the cold affected things. It was -10ºc when I was wearing the watch, and it was peeking out of my jacket driving to work.

I have parts on the way, so I'll just wait 'til they show up. It did give me a chance to make the fit of the board better. I can almost get the bottom flush with the top when closed.

[charger105]

Hi Mike.
Where the rear SC wire connects, it should feed through a little hole to connect to the battery negative. If you solder it to the strip on the SC side of the board, it will work, but I've noticed that the solder can prevent the PCB from sitting on a "ledge" in the top properly. Try mopping up some of the solder, or feed it through the hole and attach it to the other side of the board. This may help it close properly........it did with mine !

There may be a crack in the SC, or some of the strips that make up the SC may have a poor connection. I've noticed that if you apply very light pressure at various points on a suspect SC then the output voltage will vary when you touch the right spot. I've thought about re-sticking strips that have a poor connection with silver epoxy, but have never done so.......not sure if it would work ?

Is this the same watch you've been working on for months ?
Rgds,
Andrew.

[clockace]

on the red tops i use a dremel bit and grind the ridge away so the pc will fit in all the way. there is a ridge in the front also that needs to be ground down. mostly the front one needs to go to get clearance for the display. the rear one can be trimmed to fit. also the rear corners of the pc on the mkI/II's will sit on top of a little diagonal corner in the rear and not fit in all the way unless they are ground out. i use a small flat faced bit about .083" in dia and just go straight down producing a radius that is a near perfect fit of the rounded corners on the pcb. peter

[Sully008]

Hi Andrew,

I'll try resoldering the -ve through the hole. I did notice that it was soldered to the top side of the board. This is a Mk II board I'm working on. I do have a working MkIII board, just have to attach a new SC and batteries to it. No problems with it. (Crosses fingers this time)

Hi Mike.
Where the rear SC wire connects, it should feed through a little hole to connect to the battery negative. If you solder it to the strip on the SC side of the board, it will work, but I've noticed that the solder can prevent the PCB from sitting on a "ledge" in the top properly. Try mopping up some of the solder, or feed it through the hole and attach it to the other side of the board. This may help it close properly........it did with mine !

There may be a crack in the SC, or some of the strips that make up the SC may have a poor connection. I've noticed that if you apply very light pressure at various points on a suspect SC then the output voltage will vary when you touch the right spot. I've thought about re-sticking strips that have a poor connection with silver epoxy, but have never done so.......not sure if it would work ?

Is this the same watch you've been working on for months ?
Rgds,
Andrew.

[Sully008]

Hi Peter,

Thanks for the tips, I did grind away at those areas, but I guess I can go a little further. BTW, I just sent you a PM.

on the red tops i use a dremel bit and grind the ridge away so the pc will fit in all the way. there is a ridge in the front also that needs to be ground down. mostly the front one needs to go to get clearance for the display. the rear one can be trimmed to fit. also the rear corners of the pc on the mkI/II's will sit on top of a little diagonal corner in the rear and not fit in all the way unless they are ground out. i use a small flat faced bit about .083" in dia and just go straight down producing a radius that is a near perfect fit of the rounded corners on the pcb. peter

[Sully008]

Hey all,

I'm bringing this topic back to the top because the module is doing it again. But the weird thing is it's doing it while in a light source. If I leave the watch in the dark, the digits light up fine, they're dim, but that's because it's in the dark. The minute I put it under a light source, the digits light brighter, but then fade away to nothing. I put it back in the dark, it works properly. I think it's the batteries, these are the same ones that measured ~1.02v when in a non-charged state. I'm waiting for new batteries to come in.

This is a six-reed MkI module, BTW. On the plus side, I have another MkI working in a Synchronar case on my wrist as I type this.

[charger105]

Sounds like it might be the batteries.
They may have just enough "juice" left to light the display in dim mode. With light falling on the SC, it will try to light up in bright mode.

It is charging isn't it ?
It's possible that the SC is fine, and the brightness control is working, but if the diode is blown (or in the wrong way !), or if tracks are broken after the brightness circuit, it won't charge the batteries.
If you get about 3V with the batteries disconnected it should be fine.

Rgds,
Andrew.

[Sully008]

Hi Andrew,

Yup, the SC is charging fine. I checked it before I put these batteries back in. It was outputting 2.86v under the light. Too bad, I managed to seal this one back up pretty good. Shame I have to take it back apart. Oh well, I'm getting pretty good at this for a noob.

Sounds like it might be the batteries.
They may have just enough "juice" left to light the display in dim mode. With light falling on the SC, it will try to light up in bright mode.

It is charging isn't it ?
It's possible that the SC is fine, and the brightness control is working, but if the diode is blown (or in the wrong way !), or if tracks are broken after the brightness circuit, it won't charge the batteries.
If you get about 3V with the batteries disconnected it should be fine.

Rgds,
Andrew.

[Sully008]

Hey all,

Just to update this thread, I took the Sunwatch apart last night and checked the batteries. Sure enough, one of them was only showing .5v. To be safe I replaced both batteries, made sure I was reading ~2.5v when in series, and put it back together. I'm wearing it @ work right now. The sad thing is all the lights in here are fluorescent. Oh well, gives me an excuse to walk up to the front to get some sunlight.

[charger105]

Seems a bit strange that one of the batteries should discharge so much, so fast. Maybe something was shorting (even intermittently/partially shorting) when you "closed the lid". The negative tab on each button cell can easily touch the positive case of the battery if you bend it over too much, or if solder flows under it. I put a piece of plastic film under these tabs, so that if it bends over it won't short.

Hopefully you've got it sorted anyway.
Rgds,
Andrew.

[clockace]

yuuuuupppppp, i always use a small piece of plastic film between the tab and cell. i also install them with the + side up on both of them. i also have begun using the heatshrink on one of the cells to separate them. to get enough side by side clearance i cut about 1/3 of the heatshrink on the 2nd cell away so only the part on the inside is used to separate them. not sure if that makes sense w/o a photo. peter