Kevin's first attempt at battery changing and module opening

[clockace]

redcar, from the looks of the magnet placement you should be showing the time. all 4 digits should be lit up. also the 4 looks dimmer. is it just the photo, or is it dimmer? do any of the other functions lite? peter

[clockace]

you need to clean off the old gel and especially the green crud. it is probably shorting out the traces. that looks like a mkII since it has no trimmer cap. what does it look like under the solar cell? that more than likely needs to be cleaned up as well. nice photos. peter

[redcar66]

[J Thomas]

[clockace]

look closely at the sc on the display end and you will see 2 fine wires soldered into holes on the pcb, one on each end of the display. with a soldering iron + a very fine tip you can unsolder these 2 wires. on the other end of the sc there is also a wire soldered from the sc to the pcb. unsolder it as well. then you can carefully lift/pry the sc off. be very careful as it is brittle and can break easily. under that you will[i suspect] find much more corrosion. you may very well have some segment/digit transistors turned to mush from the nicad leakage. cotton swabs[q-tips] with alcohol will help in removing the gel. was the gel in yours hardened like jello or more liquid like unset jello? the unset gel is where you will run into badly corroded traces, transistors, chip legs, etc. if you have only 2 digits working it does not look good at this point. your photos really help to see what you have got there. peter

[redcar66]

[clockace]

don't give up yet. let's clean it up and see where we can go from there. peter

[charger105]

Yes, I agree.
Clean all the green stuff away, and you might be lucky.

The other side of the board where the green stuff is, is where the 1st and 2nd digit driver transistors are. These are probably being shorted by more green oxidization.

You may have to replace these transistors, but that's not the end of the world.

Rgds,
Andrew.

[redcar66]

[redcar66]

[J Thomas]

[redcar66]

[redcar66]

[clockace]

kevin, that is a digit driver transistor. the segment drivers are on the other side of the chip and there are 7 of them. the digit drivers are the 3 on your photo and the 1 on what would be around the corner of the chip on the upper right of the photo[it is not shown on the photo]. you need to clean off the gel better as well. i am sending a pm to you. regards, peter

p/s: it does show in the 3rd photo.

[clockace]

for the benefit of those dealing with the sticky gel removal. i have found that a cotton swab[q-tip] saturated with liquid lighter fluid works well. the brand i am using is ronson. it does not totally dissolve it, but it causes it to clump up better than alcohol. it will come off the pcb etc. much easier than with the alcohol. i put the sc in a small covered glass dish for a few days and worked at it a little each day. peter

[charger105]

Hi Kevin.
Yes, clean all that crap from around the digit transistors (the 4 on the left of your images). Scrape the green off from around them, and hit each attachment point with a soldering iron (some flux will help). You might get lucky and not have to replace any of them.

Rgds,
Andrew.

[J Thomas]

[redcar66]

[J Thomas]

[clockace]

i too think #1 and #2 are gone because on one of your earlier photos only the minutes segments were lit. i have changed a segment driver using just a soldering iron[a battery rechargeable with a micro tip]. archaic, but it worked. jeff is a pro at this kind of stuff. i have a post on the method i used a few posts back on the synch forum. peter

[redcar66]

[Sully008]

Yes, just connect your 3V source to the leads. You don't need the SC to test functionality.

quick question guys
can you still test the leds on the watch without the
solar cell being mounted to pcb?
Kevin