sunkko 737g spot welder modification
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- Опубликовано: 28 дек 2020
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Right out of the box this welder did weld, but only at the highest setting and only the thinner nickel plated strips that came with it. When I tried to weld 0.20mm solid nickel strips, I found that even on the highest setting the welder was unable to do its job. Sorry, I should have shown video of the welds before the modification but this video was too long already.
After modding the welder I was easily able to weld 0.20mm solid nickel even on the positive side which is harder to weld to to begin with. I also noticed that I had to turn down the current when welding the thinner nickel strips and that's the way it should work.
amazon.ca link for welder
www.amazon.ca/dp/B07XP3SS73/r...
amazon.com link for welder. amzn.to/3d4P8xa
amazon.com link for 1/4" heat shrink - amzn.to/3sFFGrL 
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![Sunkko 788H FIXED [battery tab welder] (041)](http://i.ytimg.com/vi/SXxamjDQul4/mqdefault.jpg)
I just completed my modification on my 737g / 110 volt. I used #4 superflex copper wire. I followed your U-Tube for the most part. The entire job took me 1.5 hrs. The welder went from a wimp @ 2P and 99% to a tiger @ 1P and 60 %. I would probably burn holes @ 90%. I intend to add a vent fan in the coming days. Thank you for all your advice / training video. Good job !
Thank you for the story of success.
What do u think about upgrading the pedal switch and wire, it's like 22awg wire, any input on this pedal
Thanks so much for making this I just got one and was less than blown away with it but now maybe there’s hope 😃
good luck with your mod and thanks for watching.
Thank you very much, I made the mod today on my 787A+, 3 turns of 35 mm^2 cable and now works with 0.2 nickel from 75%
You are very welcome. Thanks for watching and share with all your friends. :)
This guy is great at explaining stuff in detail. Hope you more vids bro 👍
Working on it!
Thank's for the video. I was able to do that with 4 turns with 25mm2 wire which is almost 3 AWG. I rolled the wire, then I soaped it and after 3 turns there was no place for the quarter turn. Finally I pushed a screwdriver through that and pushed down to make place for the 4. turns. Now I have feeling that it has 3x more performance then before. Nickel plated steel 0.15 mm can run at 12% 1p and before it was 45% 2P (max for 16Amp breaker). Pure nickel 0.2 run on 40% 1P. It is 220V version.
Awesome. Thanks for watching.
Couple years ago I had to use a big battery charger and a g72 battery and jumper cables to spot by hand for a 7p8s 24v 26650 pack for a power chair, just recently had to service the battery, and bought one of these spot welders. I had to run it at 99 2p in order to get it to realistically spot them properly with the thicker nickel I use. For smaller packs I've just been hitting everything with a brass brush and soldering on using a torch to heat up a slug of copper as an iron. I had a distinct feeling while using the spotter right out of the box that it would have welded better being fed by euro 220. Thanks for the vid, it solidified the idea I had regarding the transformer mod. much prefer an occasional hole to get blown rather than anemic spots. Making a set of contacts that aren't quite as thin - more of a V instead of a sharp thin point will probably help with tip erosion
Good tip! Thanks for watching.
I made the mods you explained except that I was not able to make the 4 turns like you did on the secondary winding. Instead, I was only able to fit 3 turns and that was very tight. I used 4AWG battery wire (from Ace hardware) and 1/2" shrink tubes. Was very happy with the mods and was able to weld 0.15 pure nickel at 70%/1P settings. To weld 0.2mm strips I use 90%/2P for a good weld. Before the mod, 0.15mm pure nickel strips requires 95%/2P settings to weld. Forget about 0.2mm strips it would not even stick even with 99%/2P setting. The next step is to add pencil welds. Or maybe even try a microwave x-former to replace the original one. Thanks.
Awesome. I like to hear stories of success.
GOOD VIDEO THANKS I NEEDED THIS !!!!!!!!!!!
You are welcome. Thanks for watching.
That wire look very flexible.
More strands in a wire make it more flexable. Thanks for watching.
Thanks for this tip. Mine isn't powerful enough right now even at 99%
Happy to help!
Great Video! Modified mine with 6AWG and 4 windings. works great i can now do good job on 2x 0.15 strips on 90. It was hard to measure the original secondary I think on my unit it was 6 awg also? hard to say. I tried 4awg but was to tight ended up scraping the heat shrink and cutting it. 6awg was much easier to work with. Maybe lost a little by using 6awg but works great now for 2 0.15 strips that was my goal. Thanks again!
That's awesome. Glad the video helped.
did you use the insulated jacket that came with the 6 awg
how many windings in the original unit before modification ?
Probably another option is getting a 120 V to 220 V transformer box. Takes a regular 120V power lead. You can usually get a 1000W for $25 used. Best to verify the case isn't electrically hot though.
There is usually more than one solution to a problem. Thanks for watching.
Thanks for the video
Where did you buy the secondary cable?
Princess auto. Any welding place should have it though. It's the ground wire they sell for welding.
Ok Im right in the middle of this project thanks to you :) and Im curious what size heat shrink did you use
I used 1/4 inch heat shrink I purchased from Princess Auto, but here is an amazon link just in case.
amazon.com link for 1/4" heat shrink - amzn.to/3sFFGrL
@@thecityviking I have 8mm coming thank you!!
How did your turn out
@@jasperhart1188 It got the job done but still didn't seem hot enough
What size heat shrink did you use to fit over the 4 awg wire? Was it standard or dual wall
The heat shrink I used was 1/4 inch single wall I purchased from a local store called Princess Auto. It's an inexpensive made in China heat shrink, but most transformers use wire that just have a varnish coating on them for insulation, so this should be good.
thanks for watching
Thxs for the video. Doing this mod now, but I can't get the paper on. Got 3 turns on it.
The paper is there to stop the sharp edges from cutting into the insulation on the wire. If your insulation is thick enough you should be ok. Thanks for watching.
Hello, great video, congratulations, so what you did was replace the original 2-turn secondary with one of the same 4-gauge to give it 4 turns?
That's exactly it. Thanks for watching.
I'm trying to this, but after calculation, I decided to use 35mm cable 3 turns
Because if I use 25mm cable as original and goes 4 turns, heat will be I^2R, Secondary winding goes double means double resistance and double current, that make 8 times heat than before, so I use 35mm cable goes 3 turns try to cancel that extra heats out.
I have the same machine and i am in the middle of the job, just realised
in mine 4Gauge\25mm2 will never fit.
Gonne buy some 6Gauge\16mm2 and gonne try again.
Still dont get how it fits in yours so easy and in mine there is not chance 4Gauge will fit.
From a physic point i also dont got it yet why we chance the insulation
against another insolation. We are just doing this for size reasons?
So it fits better?
If 6 Gauge fits stright can i use it stright with the insulation it has from factory?
Would make the job even easier.
Generally thicker gauge wire is better, that is why I removed the insulation. With the thick insulation removed and the thin heat shrink, I was able to get the heavier wire in. The energy is transferred in a transformer by the magnetic field, so thicker insulation shouldn't have a big effect except that it is spaced further from the field.
I hope that helps clear things up, and good luck with your mod.
I just ordered one of these to assemble 2170 battery packs with 0.15 pure nickel strips. I had tried to build my own with a 500F 2.8V capacitor, but the capacitor had too much internal resistance and I couldn't get a good "pop" out of it. More of a slow burn. And now seeing this video before I've even received my welder, I'm bummed (that it's too weak out of the box) AND encouraged to know there is such an easy fix. I'm thinking the gauge of the wire is maybe not super important (within reason) unless you plan to do LOTS of welds in a short time period. If I want to add extension leads, will it work to continuously hold up the arms (to satisfy the limit switch) and only use the foot pedal, or does the limit switch on the arms need to cycle on/off between each weld? It seems strange that the 110V version is weak vs the 220V version, because the primary on the transformer clearly is set up for either. I assumed you checked to make sure the primary was correctly configured for 110V operation. It really should work the same if the primary is wired correctly. It also makes me wonder if their controller is monitoring something (like primary current) which would be higher on a 110 unit, and if it is shutting down too early (too short of pulses) because it thinks its giving more power than it actually is?
It is may be a 110 Volt AC transformer (? looks like an microwave oven transformer ?)
A lot of owner with 230 Volt AC have problems with there 16 Amp standart circuit braker.
One spot and these owner have to go to the circuit braker ...
An not perfect work around (not allowed) is to use a 20 Amp ciruit braker
(not allowed with a wall plug max 16 Amp peak ).
Other owner use a 25 meter cable (with cable on the drum) between the spot welder and the AC wall plug.
The copper resitance and the induction ! The ciruit breaker stays on.
Both work a rounds are not allowed in my country.
How is this wired to 220v? I wanna add this copper wire to the transformer but I also wanna 220v wire this. But how is the wire done to the circuit board in the transformer? Any links or tips? Cool video
@@jasperhart1188 replace transformer you can just buy euro version instead its cheaper
Nice video. Did you ever add a pen to the setup? Would you pigtail secondary leads off of the transformer, or would you need a switch or relay?
I have some external leads that I plan on adding. I would just parallel of the existing wires. The welder pins and the added external leads would have power when welding, but all the current would flow to whichever you are using. A relay would probably just melt after a few welds.
Maybe I should make a video showing my pen mod?
Thanks for watching
Nice modification. Idk why this version have only 2 turns. The cable should be 25mm² thick and no less than 3 turns to weld 0.20 mm, even 0.15. Doesn't matter weather is 110 or 220 volts, the amperage is important here, more turns and thicker cable, lower voltage and higher amperage. Well I learned this hard way cause I build my self a DIY battery spot welder machine with transform from a microwave and first try with 2 turns 25mm² black thick isolation cable for arc welding. After that I bought from this clear, soft silicon Chinese cables 25mm² because there us no place for more than 2 turns with the black. So with 3 turns can spot welds 0.15 and 0.20 on lower milliseconds without heat.
I don't understand why this welder only has 2 turns as well. thanks for watching!
Here's ideas self a DIY pneumatic battery spot welder machine with transformer from a microwave with 3 turns 25mm² black thick isolation cable.
ruclips.net/video/bOLO600N2Jg/видео.html
Hi friend I have a cuestion
That is a nice rig!
Technically, its not true regarding the voltage and amperage with more windings. The more windings you add, the voltage goes up but the amperage decreases. The primary coil windings are fixed and the secondary depends on the number of turns. As the turns increase, the voltage in the secondary goes up, but the current goes down.
Great video could it spot weld pure micro 0.2mm without the mod I’ve just bought one.
If you mean 0.2mm pure nickel, no. At the highest setting it could barely weld the 0.15mm(0.13mm measured) nickel plate that came with the welder.
WHEN YOUR DOING LARGE BATTERY PACKS .. HARBOR FREIGHT SELL THE LONG COPPER PINS THAT WILL LET YOU WELD THEM. THEY ARE LIKE 12 INCHES LONG IF YOU SEE WHERE I AM GOING WITH THIS !!!!!
I am working on adding welding pens right now! I will upload soon.
You basically doubled (or more) the voltage on the secondary winding , right?
By doubling the secondary windings it should double the voltage. That being said I didn't measure the voltage beforehand but the voltage after the mod was still less than a volt measured with my Fluke 177 set on min/max. Perhaps someone with a scope can get a more accurate measurement.
@@thecityviking just received my 120v version of this, I live in Australia (240v) but wanted to test it out, connected it to my oscilloscope after doing your mod, the voltage read less than a volt till foot switch pressed (it’s got a relay in it to switch power) but the voltage read double ranging 8.3v to max 9.4v, asked a mate who welds for a living, he said that you are still doubling total power generated, just more voltage, all it means is this is more likely to have less cleaner welds than more current and have a slightly higher chance of damaging the batterie, but in my experience at that voltage still generating enough heat to weld tabs to battery and so far no damage to 50 lithium cells I have used, thanks for the awesome video! I’m an electrical engineering student and love doing mods like this!
@@hrox112 do you think doing this modification it’s worth doing ?
@@hrox112 having thicker wire gives high current more turns give more voltage. That being said the look of the original wire not being tightly wound together will give lower current to some degree. A slightly higher voltage should damage much as you can adjust it. 4 turns at a.c. over 2 volts a.c. won't do much harm.
Bris. Qld
Doubles the voltage and halves the current.
Awesome video! If you’re willing, I’d love to see the pen mod. Been trying to figure out a way to add one for days. I plan on doing this, as well as a pen/individual leads.
Funny thing is that there are some knock-outs on the front probably for a pen option. I will record my mod and upload very soon!
Mine doesn’t seem to have any spaces for a pen, I plan on splicing it into the wires currently connected to the welding arms, after I recoil it as per your video! I’ll await your video!
Great idea. But I just got one, put it to 99. Was like meh. Then I started welding the strips but not putting much force down. Badically just touch the points.
hmmm....Ill try that!
Hi just finished the modification on my 737g/220 vet and after putting it all together all lights working but no weld 😢 any idea as to what could be wrong,still a very informative video,thanks for any help in advance
It's hard to tell without looking at it, but here are a few things to look for.
It sounds like you have power to the circuit board, but the transformer is not getting power to it. The transformer is switched on momentarily from the circuit board only when you are welding.
Check that no stray wires are shorting.
Check the connection of the high voltage wires going to the transformer are not broken. (These are thin wires and could have come loose while installing the new secondary winding)
Good luck with your trouble shooting.
thanks for the reply, ive looked into what you said and there was a loose wire going to the transformer but after soldering back still no joy, on reflection i think it could be a faulty transformer if so is there any way of checking that out, thanks again Tony @@thecityviking
hey man i followed this, and bothr at 3 turns and 4 turns my welds are even weaker, is there any explnation to this im using two oxygenfree copper 8 gauge cores combined and be it 3 or 2 turns im just gettign even weaker power
Thicker wire usually increases the current, and more turns increase the voltage. Longer lead wires outside of the transformer may cause more losses, but otherwise I am at a loss.
I cant fit to make a 4 turns with the space of my shrink tube.. can i shrink the tube? Will it still work?
You can absolutely shrink the heat shrink. You can flatten the wire out with a rolling pin or bottle as long as the insulation/heat shrink is not damaged you are good.
The cx4500 with two pens and foot pedal i think is better to work and has a bigger transformer inside.
That may very well be, but I already purchased mine and decided to fix what I had and show others how I did it. Thanks for watching.
Thank U!
You are welcome. Thanks for watching.
Oh. My. God. My Sunkko 709 AD (120 V) has been sitting in the corner for three years since I bought it because it never worked. I happened to have a bunch of 6 AWG welding wire around so I followed this video and now the darn thing actually works! I went ahead and removed the built-in welding prongs, so I wound up taking the secondary windings directly to the PA OUT. Also, after removing the original insulation from the wire and wrapping it in Kapton tape. My transformer tolerances were so tight I have no idea how people are getting 4 AWG in there, but the 6 AWG is working great for me.
Thank you, CV!
Thank you for your story of success. I am currently working on a pen mod for welding larger packs so stay tuned if you are interested.
Could you had re-wired the transformer to 220V? I saw the transformer tear down on another video by powerelectronicsblog.
You can absolutely change over the primary to run off 220v. I was originally going to do that to see if I could get it to weld my 0.2mm pure nickel strip. The transformer would be the easy part, you would have to make sure the pcb would not be getting too much power. The mains go directly into the pcb(not using the transformer)
I ordered the 110v version of the 709ad+. Thanks for the heads up. I’ll have to see the internals of that unit. I can probably use the 110V coil to power the control panel using separate wiring.
I don't think that will work. The control board has the main AC running to it to power it and it switches the transformer on and then off to make the weld. So the transformer has no power running to it until you trigger a weld. My control board has 2 big resistors in it that I though was a voltage divider. It then has a chip(I believe an LED driver) that it is using to supply power to the board. The board uses very little power so this LED driver powers the whole thing. The LED driver (if I remember correctly) takes AC in and provides DC out.
If it works well with 110v, I will leave it alone. If not, I will have to come up with some way to supply the board with a separate 110V source and convert the main transformer to 220v. It may just need a separate 110v power cord wired to the board. I’ll have to see the actual tracing.
He doesn't show the wiring of the circuit board. Where to connect the wires
worked great! but now blows the fuse everytime i turn it on (after a grumbling sound) any ideas? thanks
Does it blow the fuse when you turn it on, or when you activate a weld? If it blows the fuse right away then it may be a problem with the board otherwise it may be the transformer. Try unplugging the transformer and see what happens to narrow down the fault.
thanks for your reply. It was working for a bit but as soon as i put the cover back on the box it started doing that I figured it was because I stuffed things together too much and something was shorting, but now seems to do this regardless. I haven’t tried narrowing down the problem I will tonight though. Last time I tried it as soon as I flipped the switch I saw something glow white for a second hopefully it was only the fuse blowing. I picked up some slow acting fuses I was going to try as well ...hope I didn’t fry this thing
I’m wondering if maybe my heatshrink tubing shredded up and caused a connection to those plates, it was hell getting it in there. Because I think the ground and the probes had continuity when testing it recently but since then I fixed that but haven’t tried again because I need more fuses. could this be the case? Thanks
You should have the paper separating the wire from the transformer case, but I think a short there could definitely be a problem that may cause the fuse to blow. There should be no power to the transformer until you press the foot switch or the switch on the welding arms.
Did you wind it in the same direction as one removed?
3 turns on output side and 4 turns on input side?
I am not sure what you are asking here.
Has any1 upgraded the pedal wire and switch, my pedal switch say 120v 2a and it's 22awg or smaller wire
I don't think the switch switches the main load, but I will look at it and get back to you.
@@thecityviking I've been researching, haven't came across much, not much on how electricity travels threw a switch, but their are higher capacity switches. I'm curious how it affects the power output.
So this is an ac spot welder not dc?
I suppose it is. Thanks for watching.
The current isn't a percentage, it should be how many ms it keeps it on for. 99ms being the max, 0.099 seconds.
The current numbers do represent a time, but without proper documentation, we can only assume what time reference. A percentage number makes sense because they CAN be represented as a percent. If the time reference is from 1ms to 99ms, then 20ms=20%. What if the time reference starts at 41ms and goes to 139ms? Well, then 60ms would be 20%. I don't have a scope to measure this time, so a percentage makes sense because it works with any time frame. Hope this makes sense, and thanks for watching.
@@thecityviking in my case the 737b I've got came with a manual saying the numbers are how many milli seconds the pulse stays on. If you set it all the way down it does practically nothing. So I think it's safe to say the numbers are 1:1 with the actual time. Although mine is a slightly different model and I suppose they could have offset it a bit. I doubt it though.
hallo sir, can I repair jewelery with this machine?
I have not tried to repair jewelry with this device. I don't think it would work very well, but perhaps I am wrong.
i have bought it also, i think the 120v and the 220v version ar the same thats why 220v has no problem welding....
the problem with my unit is the instant i make a weld my home fuse blows.... :S
the welder is max 15Amp. My home fuses r 16Amp per group. any suggestions or ideas how to fix this? anybody any one??? ?? :(
i don't have that problem, but I would try different outlets. I have heard that newer breakers are more sensitive, so try an outlet that is on an older breaker if possible. A power bar with a good surge suppression on it might help too. Good luck and thanks for watching.
I read that as g spot welder
Lol. That made my day. Not sure what a g spot welder would be, but it made me check the video title and now I can't unseen it! Thanks for watching
Do you sell? how many $
Sorry I don't sell, I only make the videos. Give it a try, it's not too hard to do!
@@thecityviking use for good day. It is nice
Если ты русский, ставь лайк)
More windings then the voltage goes higher. Logical ? It physics
Less windings then the voltage is lower. BUT
But the max Amp raise.
In both case you get the same Watt output.
Result = less windings higher Amp and more windings Amp is lower to spot weld.
Physics
But you need for spot welding not very mutch voltage. You will have a lot Amp.
Less windings and thick cooper is best.
But not one winding please. You need some voltage.
A vent ? No the heat is only at a fraction of a secound.
The spot welder transformer is not realy hot.
Ok when you spot weld a lot ...
The 105 dregree Celsius contact braker is a good safty solution !
For owner with 230 Volt AC main ...
may be this is a 110 Volt transformer. I dont realy know it !
You problems with the circuit braker ...
may be that is the reason.
Work around is not fine and may be in your country not allowed ...
use a 25 meter extension cable and wind it around a drum.
I heard of it and these guy have no problems / less problems with his 16 Amp ciruit breaker.
And in 230 Volt AC main countrys ...
... your wall plug is max 16 Amp.
Ok, the spot welder need very mutch more Amp at 230 V AC for a fraction of a secound.
But in fact it will be mutch higher than 16 Amp.
In your country it may be not legal to pull over 16 Amp out of a wall plug. And your wall cable plus connectors in the wall ...
.. at your own risk.
May be it is not ok in your country.
Beware of hidden fire and or very very hot cable + connections even in a fraction of a secound. Fire can be possible.
Ask you local electrician !
In US with 110 Volt AC the copper diameter in the walls, the wall plugs and the fuse Amp
are different to 230 Volt AC countrys.
The welder from factory would not weld the thicker .2mm strips until I made the modification. Now it works very well. Thanks for watching.