Quoted from kapsreiter:
everything at the pcbs is prepared for it
i think the wanted to save less then 1 euro at this product, grazy
you will need
1 DS1307 sms realtime clock RTC = U3
1 Quarz quarz, 0,032768 MHz = Y2
1 battery 3V
running since a view hours without problems
also unplugged it for more then 15 minutes
and the perfect time after reconnect
So I'm gonna post my failed attempt at making my clock keep its settings when it's off lol. At the very least it might help someone else not make the same mistake I made.
So I got the 3 parts (chip Quartz and the battery) to make my clock save its settings when it's off.
First getting the clock apart wasn't as easy as it looks. 4 screws in the back, then you have to pry off the plastic tint in the front. (It's glued on the corners) then you have to pry the LED board out (also glued). Now that I know how it shouldn't be a problem again.
The board is deceivingly small. Which means the soldering spots are very very small. It wasn't too bad soldering the Quartz Y2. Soldering the battery was tough. Two wires to the board was simple but soldering those wires to the battery wasn't working for me. I would get one side then do the other but the battery would get so hot when trying to do the other side that the first side would come off again. I ended up just taping the wire to the battery just to see if it would work.
Now the DS1307 chip. The ones I got were bigger than the spot I needed to solder into. On top of that I wasn't sure of which way it should face. The board doesn't have the little square showing which way it should go. With a little schematic searching I went with it faceing the battery. Soldering this was very tough with mine being bigger and the solder spots on the board being so small. I felt I got it though.
I plugged the clock in and my best result was it was saving the time when I turned it off. So I would unplug it at 10:07 wait 10 minutes plugged it back in and it would still say 10:07. I double checked all my soldering and even tried the chip the other way (it got hot so I think I had it right the first way) I really think the DS1307 chip I had was wrong since it was so much bigger than the spot.
Any advice would help. I ordered the smaller chip so I'll give that a try next. In the end I'm just glad I didn't permanently damage it lol.