Replacing Solar cell questions.

[Sully008]

Hello all,

I recently purchased a dead Sunwatch to see if I can get it working again and tonight I managed to open the case without too much damage. Problem is the all internals were pretty much turned to mush.

Luckily, the watch came with a bunch of parts and a brand new solar cell. I found a module/PCB that had a working display, IC and reed switches, but no solar cell. I've found some great info in the reference section here:

http://www.dwf.cc/viewtopic.php?f=21&t=230
http://www.dwf.cc/viewtopic.php?f=17&t=23

But I have a couple of questions:

How many wires are supposed to be connected to the solar cell? The one I have only has one wire.

If the one wire is correct, does this get soldered to the +ve location as indicated in the second link? I'm not sure if that circuit board is the same as the one I have.

If 2 wires are required, where can I solder the second one to on the cell, and where would it go to on the circuit board?

I've got a set of Varta V80 batteries coming from Mouser. Hopefully with the help of the forum I can get this watch up and running again.

TIA,

Mike

[clockace]

the one i replaced has 3 connections. one on each corner at the display end and one on the other end at approx. 2/3 to the right edge. that would be the lengthy solder connection the the view topic site. the other end went in the solar - position on the diagram. the opposite corner wire goes thru the little hole and has a tiny plate soldered to the backside of the pc. there is no real connection to anything. i think it is just to stabilize the edge of the sc at the display end. it looks like only 2 connections are necessary, a + and a -. mine is working so i guess i got it right. peter

[Sully008]

Hi Peter,

Thanks for your reply. I've been reading that link over and over again and it looks like I need two wires on the SC. One is already soldered to one side of it, I guess I'll have to add a wire to the other side, and figure out which one is +ve, and -ve. Just realized that my circuit board is probably a Mk III, since it looks like this one, but I can't tell where the SC is connected to. I'm guessing in the same spots as the Mk I.

[clockace]

hi, thanks for the photos. you must have either a mkIII or IV there. it is much different than the ones i am working with. in the lower photo it looks like the soldered connection on the right of the photo is in the right place and the soldered connection is off from the lower edge on the left. if you put your probes on each connection under a light you should get 3-4 volts. maybe the mkIII/IV's only have 2 wires. that is all that is needed anyway. i got some sc's from howard and he did mention that he had to resolder the connecting wires differently for the mkI/II's. i got my first cells from mouser as well, but batteries + has them also. they charged me $2.87 for them and $1.00 more each for solder tabs. is the display on the right side of your photos? if so, i think it looks right. if not, maybe someone else on the forum can help better than i. regards, peter

[charger105]

There should be 3 connections. Two positive, which attach to either side of the display, and one negative at the back, which connects to the battery negative. As Peter suggests, I believe one of the positive connections to the board is just for physical stability.

Make sure you're getting about 3V at the battery connection points (under a bright light) before connecting up the batteries, and sealing the case.

Good luck !
Rgds,
Andrew.

[Firefly]

There should be 3 connections. Two positive, which attach to either side of the display, and one negative at the back, which connects to the battery negative. As Peter suggests, I believe one of the positive connections to the board is just for physical stability.

Make sure you're getting about 3V at the battery connection points (under a bright light) before connecting up the batteries, and sealing the case.

Good luck !
Rgds,
Andrew.

Hi there
I agree with charger105 it's 3 connections 2 positive attach and 1 negative at the back



look the next picture 2+ in red and 1- in blue



This is my MKIII without chip silicon because i lost it see beelow

[Sully008]

Hi all,

Thank you very much for the pictures! It all makes much more sense now. I can resolder the two +ve connections back on. I only had one @ the back of the SC which I'm assuming is the -ve. Then I'll confirm that it's working with my multimeter.

[Sully008]

Hi there
I agree with charger105 it's 3 connections 2 positive attach and 1 negative at the back



look the next picture 2+ in red and 1- in blue



This is my MKIII without chip silicon because i lost it see beelow

Hi Firefly,

I just want to confirm that the first two pictures are the topside of the IC and the third is the bottom side, correct? I've got a bunch of those ICs too, I haven't had time to test them yet, though. I lucked out and the first one I picked was working.

[Firefly]

Hi there
I agree with charger105 it's 3 connections 2 positive attach and 1 negative at the back



look the next picture 2+ in red and 1- in blue



This is my MKIII without chip silicon because i lost it see beelow

Hi Firefly,

I just want to confirm that the first two pictures are the topside of the IC and the third is the bottom side, correct? I've got a bunch of those ICs too, I haven't had time to test them yet, though. I lucked out and the first one I picked was working.

Yes it is it's that the 2 first pictures are the topside and the third is the bottom side you can see the resonator with 2 resistors

[clockace]

sully008, do you have an email address? i have been trying to send you pm's, but they are not going thru. peter

[Sully008]

sully008, do you have an email address? i have been trying to send you pm's, but they are not going thru. peter

Hi Peter,

Pm sent. Let me know if you got it. Mike

[Sully008]

Hello all,

I just wanted to update this thread. I soldered 2 leads to the bottom side of the SC for the +ve connections. Then I managed to solder the SC to the circuit board as per Firefly's pic. But I have a problem. When I measure the SC on the top (indicated in red and blue in Firefly's pictures) it measures ~3 volts. But when I measure the voltage @ the battery leads, it only measures ~1.2 volts. Did I do something wrong? Also, when I connect 3 volts to the battery leads, the display lights up part of the segments, but then goes dark. Putting a magnet to the reed switches does nothing. Before I had the SC attached, when I directly put 3 volts to the leads without the SC all the segments lit up. Help??? I'm going to stop at this point.

[Sully008]

One more thing I noticed...On this pic from Ed's site:



The +ve connections appear to be on the top, with the negative on the bottom. This is how I have it. But in this pic from Firefly:



It looks like the -ve connection is on the top, with the +ve underneath. Which one is correct?

[clockace]

hi, in looking at the photos with the red and blue highlites, i think the reds are the - and the blue is the +. i have a schematic and it shows the solar - connection on the display end of the module. the + is on the end with the qc. the schematic is from the view topic part of the forum under "how a synchronar works" posted by ledwatch. go to the "circuit diagrams" forum. you need to register to access that site also. peter i am going to edit this post. when i put the probes to the sc the + is on the end at the display, unlike is noted on the schematic . a clearer photo of the schematic shows the solar connection in the lower left of the photo to be a +, not a -

[Sully008]

hi, in looking at the photos with the red and blue highlites, i think the reds are the - and the blue is the +. i have a schematic and it shows the solar - connection on the display end of the module. the + is on the end with the qc. the schematic is from the view topic part of the forum under "how a synchronar works" posted by ledwatch. go to the "circuit diagrams" forum. you need to register to access that site also. peter

Hi Peter,

I've looked at that diagram as well. So, if I flip the SC over so that the 2 leads are on the bottom, that should work? Or am I supposed to turn the SC around so the one lead is connected to the front near the display, and one of the other ones is connected to the back of the IC?

Here's another pic from an earlier thread showing the SC. In this one it looks like the two leads are underneath the SC. This might lead me to believe that it should be flipped over.



It's late and my head hurts. I'll buy solder wick tomorrow and try flipping it over. Thanks for all the help, much appreciated!

[clockace]

hi, you are up late too. the solar cell i replaced had 2 leads on one end and 1 one the other. the end with the 2 leads i soldered on the pc board end with the led display. only 1 lead makes a connection with the pc circuit. the other lead just goes thru a hole in the pc and is soldered to a tiny plate that is connected to nothing. i think it is just to stabilize the front end. the other lead is soldered to the back end of the pc where the reed switches are. at least on the mkI/II there are reeds on the back end. it is soldered to a small rectangular connection on the back end. the schematic does not show this spot well, but it is in the upper right corner of the schematic. this schematic shows a dot matrix display, which is what i am working on now. it is a really cool display in 24hour format. hopes this helps. peter going to bed now by flipping over, do you mean turning it end for end? i think you want the dark side up.

[Sully008]

by flipping over, do you mean turning it end for end? i think you want the dark side up.

Hi Peter,

By flipping over meaning like flipping a pancake. Instead of having the two leads on top, they'll be on the bottom, but still connected near the display.

[Sully008]

Ever had one of those "AHA!" moments in the middle of the night? I did. Peter, I think you're right. The SC needs to be spun around 180º. When I was reading 3v it was with the +ve probe of my meter @ the display. But if the display end is actually ground (which makes sense, since the other lead goes nowhere, other than a plate), then the tail end of the IC connection must be +ve.

I can't wait until I get home from work to test this out.

"I can see clearly now, the rain is gone..."

[Firefly]

Hi

Oups my solar cell is not installed such as yours. sorry about that

[Sully008]

Hi

Oups my solar cell is not installed such as yours. sorry about that

Hey Firefly,

No need to apologize, I should've done my due dilligence first. Hopefully this will fix things and I didn't do any permanent damage to the chip.

[clockace]

hi, there seems to be some confusion about the +/- end of the sc. when i put the probes to it, the + is on the end at the display. the dark side is up, and the louvers,are facing towards the rear, looking like a closed venetian blind. the sc's i got from howard are wired by him for the mkI/II. it may be different for the mkIII/IV. in any case i would just try turning it 180 degrees, or end for end, and see if that helps. it can only go one way or the other. peter. i just got a clearer photo from phil and the position in the lower left where it says "solar connection", what looks like a - is really a +. so that should straighten everything out. this last sentence is an edit of the first part of this post. peter

[Sully008]

Hello all,

Well, after several hours of troubleshooting tonight I've come to a roadblock. My SC is soldered to the board correctly, the 2 +ves on either side of the display, and the -ve at the back near the QC. I can confirm that there is +3v from the SC at it's contact points to the circuit board. What's puzzling is when I check voltage at the battery leads it's only reading ~0.9-1.1v. I hooked up a 386 battery as a suggestion from retroleds and all I get is a partial digit lighting up. No reed switches work. I don't know what else to look for at this point.

I do have a set of Vartas coming in, but I highly doubt that'll make a difference. Thanks everyone for all the help, but I think I'm going to put this project on the shelf for now, unless someone has any ideas.

Mike