Having A Crack At Replacing Synchronar Cells.

[bucko170]

Although it has been well documented in previous threads I thought I'd join the trend and have a crack at opening up a recently purchased Synchronar module.

I used a Dremmel to run around the joint between case and back plate and then prised it open carefully with a screwdriver - this worked well and I was pleased with the results, only minimal damaged around the joints, no cracked lexan.



The dead cell was surrounded by white power from where it had degraded, (not clearly visible in the photo's) the good news is the potting gel has served to contained itaway from the PCB



I scooped out the gel and removed the old cells, one was dead but surprisingly one was still giving out a steady 1.3v on the multimeter





Having removed the batteries I tested the solar panels and found them giving out a good charge.

I prepared the replacement Varta batteries, using some conductive silver epoxy to connect up the + to - and two leads to connect up to the solar panels. I choose to use the epoxy as I can see that space is going to be very limited, although it looks a little messy, I thought without solder tags the batteries would take up less space.





Then before joining it up and trying to fit it all in the case I gave it a final test and all worked well........... until DISASTER struck when one of the wires from the PCB snapped off

Soldering a new wire is to big a challenge for me so I have sent it away to be soldered and I am waiting with fingers crossed that the soldering can be done.

Will keep you posted.

Regards Mick.

[charger105]

Bad luck with the broken wire Mick. Re-attaching it should be a very simple task. I'm sure whoever you've asked to do it will be able to do it for you.

I've opened up a MkI and some MkIII modules just using a craft knife. I ran the knife carefully around the joint, continuously until it penetrated right through. Very little Lexan loss. You have to be careful not to go too far around the display area.

I've thought about using conductive epoxy, but I think tabs would actually take less room than a wire glued down. So long as you can put the back on, I don't think it matters much.

On another note, there looks to be a bit of corrosion where the trimmer capacitor sits.....I hope this doesn't affect things.

Rgds,
Andrew.

[bucko170]

I managed to test the watch before the wire broke and it functioned ok, I noted the corrosion around the trimmer cap, just seems to be isolated around the top of the trimmer cap. I don't know why it should occur just at that one particular place, I was just going to clean it off best I could before sealing it back up - what else can you do?
Regards Mick.

[retroleds]

The wire repair isn't a hard job, just not in a terribly easy place to get to, without the module out of the case top. The conductive epoxy is probably a pretty good choice for the battery conections. It's not so much that the battery tab is so big, but soldering it or the wire directly on could cause some damage to the battery. Varta says on their web site that the batteries can be safetly soldered if they are charged and the soldering time is kept to a minimum. Basically scrub the battery case good with some sandpaper to prep the area, clean it with rubbing alcohol and use some soldering flux on the wire and the battery. You got lucky on your purchase - those red bottom ones are the easiest to open....wait until you come up against a black bottom one. A seriously different opening job.

THe screws on those trimmers appears to be brassy/coppery...not surprising that it would react to the lightest amount of acid. Good job on the opening!

[bucko170]

Thanks Ed,

I had noticed the difference with the black bottom ones.

I bought some spare parts off ebay which included the black bottoms and noticed how tightly the batteries fit into the wells on the base.

Surprising how many different variations there are with the Synchronars, especially as they all look very similar externally.

I like the red bottom Synchronars as you can see through to the workings.

Regards Mick

[Synchroserious]

I just spent 1 hour trying to type the proper help and The Message was deleted Why why ED????

[Synchroserious]

Don't use silver epoxy to make a battery connection

[Synchroserious]

Don't install batteries with green rubber insulator

[Synchroserious]

Never never solder directly to the batteries

[Synchroserious]

Use insulating tape underneath both cells and between them.

[Synchroserious]

Use insulating tape underneath both negative terminals

[Synchroserious]

Have the tabs double spot welded on, "Batteries Plus" will do it for you.

[Synchroserious]

Don't use black electrical tape. Use electronic type. I use Teflon insulating tape. Not the white kind used in plumbing.

[Synchroserious]

It,s a pity someone with first hand knowlege is blackballed by an ignoramous jerk When are you going to grow up Ed?

[retroleds]

I didn't comment on the insulating because I figure that would be normal electrical procedure. The soldering is no more heat than spot welding. You are welcome to your opinion that silver epoxy is not ok - I am welcome to mine that it is. You had no good reason for unloading on me for answering a guy's question - doesn't seem like you have been on for a while anyway.

Try behaving, you're disturbing my peace. Now go in peace.

[Synchroserious]

My freedom of speech to help people had nothing to do with your comments or anything negative about you.Nor was i disrespecting you when you had delusions about me disrespecting your wife.Your the one who sent emails to everyone stating she helped you catch up.Don't be so paranoid just because you are aware that i have good reason to be upset with your actions. You have caused enough delays with my progress at helping people and keeping my fathers legacy alive.

I forwarded your nasty email to several people here. Charger105 did not go through because of your vulgar language in the mail that caused a failure demon because of the F word you used, clever

[Synchroserious]

I didn't comment on the insulating because I figure that would be normal electrical procedure. The soldering is no more heat than spot welding. You are welcome to your opinion that silver epoxy is not ok - I am welcome to mine that it is. You had no good reason for unloading on me for answering a guy's question - doesn't seem like you have been on for a while anyway.

Try behaving, you're disturbing my peace. Now go in peace.

Try learning something dude. Spot welding is quick and precise if the machine is adjusted right.Attempting to solder to a battery is a different ball game that keeps heat directly on the Pos or Neg cell for many seconds longer. about enough to ruin the battery or have it blow up in your face. Big difference.

[retroleds]

Properly prepped, with an 18 watt iron, solder time is less than 2 seconds with silver bearing solder - just a dab will do it. And with a tab spot welded on, you have to solder to the tab, giving it a second dose of heat. Myself, I often solder things I want to keep cool on top of a damp rag...something I learned doing stained glass work. A plastic drink straw between the teeth is also a nice way to give a cooling blast once the soldering iron is lifted. But the spot welding is fine if you are more comfortable with that. Now matter how it is adjusted, a spot welder is being asked to melt a small amount of the steel jacket onto the tab; whereas, solder flows on and stays thru static adhesion. Only the solder has to melt.

[Synchroserious]

I only speak the true facts. You are sounding like a hipocrite again to me.

Are you actually promoting the idea of soldering directly to a battery . Spot welding of battery cells terminal to terminal has been done for years man come on.How do you think they make battery packs with spot welded tabs.Varta does it to. How do you think they come up with battery packs of 2.4v,3.6v,4.8,6v and 7.2??.... all multiples of 1.2 cells with a tab spot welded to connect them.
Sorry it upset you that i do not recomend silver epoxy or a possible novice attemting soldering to a battery. There is a safty issue there man. Just because someone says something cross to your oppinion does not mean they are attacking you and certainly is no grounds to erase my efforts to help people do it right.

[retroleds]

Yep, that is what I am suggesting, they just need to be quick and clean. Spot welding is faster in a manufacturing environment, but many battery packs over the years have ben soldered in this fashion. Still not sure why you are so down on silver epoxy. And you are back to the name calling, for no good reason. It would be hypocritical if I did it differently myself while suggesting it to others. I have no idea where I was erasing out your opinion - I didn't knock you method at all, but I think there is a place for other methods. Not like the factory jobs have been known for stability and long life. Since they are way out of warrenty, I think we are allowed to try something different.

And yes, I have pretty much caught up on the outstanding work. It's never really all done...always somebody who wants something put together for them special. Or at least talk about it.

[J Thomas]

[retroleds]

J: I agree, the pissing match is not pretty. My erstwhile adversary tells me he is committed to fighting with me - so it has came to an end. This site cost about $3000 in first year costs and countless hours - I don't mind someone disagreeing with me, but they can't go for the jugular "just because". Personally I would be inclined to go back and remove all the detritus(trash) from this thread and only leave my suggestions and Howard. But the greater body that comes here has historically cried foul at that - some consider it entertainment(I personally do not). I do appreciate being reminded it has gotten out of hand - I have an erratic, tempermental streak, like many. I apologize for not just letting it go..

Regarding the soldering: Google "soldering to batteries" and you will find that it is actually described by most manufacturers and is not considered a problem, if proper precautions are take. Clean well, flux, solder for just a second. If every thing is properly cleaned and the metal scarified/scrubbed, a drop of solder on the tip bonds instantly. And you can certainly have a moist rag handy to press against the battery to sop up the majority of the heat very quickly. The Varta batteries are actually fairly substantial in size, having almost twice the volume of a #357 battery. Look at the size of them and some welded tabs: http://www.thedigitalwatch.com/Archives ... bottom.jpg

Many of these tasks should be undertaken by people who are experienced at the tasks, as they all sound easy on paper. Sort of like explaining a triple-axel manuveur in skating," just jump up and spin three times". Right