788 spot welder

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robocam   10 kW

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Re: 788 spot welder

Post by robocam » Mar 02 2016 11:39pm

What do you all think of this welder?

http://www.ebay.com/itm/3-DAY-SALE-Batt ... Sw9mFWIsZd

Is this the 788 being referred to? Is there a way to use handheld probes? It would seem difficult to hold a huge battery to the machine.

http://www.ebay.com/itm/181922221370?_t ... EBIDX%3AIT

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Re: 788 spot welder

Post by Syonyk » Mar 03 2016 11:50am

robocam wrote:What do you all think of this welder?

http://www.ebay.com/itm/3-DAY-SALE-Batt ... Sw9mFWIsZd
No idea. It doesn't give anywhere near enough information that I'd be willing to purchase it. Single pulse? Double pulse? How long? How adjustable?

If it's "tap the foot pedal and it goes," you'll have radically inconsistent welds and burn through a few batteries.
Is this the 788 being referred to? Is there a way to use handheld probes? It would seem difficult to hold a huge battery to the machine.

http://www.ebay.com/itm/181922221370?_t ... EBIDX%3AIT
Yes, I think the 788H is the newer version of the 788+. You can wire up handheld probes if you want, but I haven't had to worry about it - I've just learned to build packs within it's constraints. I'm not building huge packs, though.
Battery packs, Sunkko Welders, and more. http://syonyk.blogspot.com/

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robocam   10 kW

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Re: 788 spot welder

Post by robocam » Mar 03 2016 2:35pm

Yeah, it stays on as long as the switch is pressed. The ebay feedback from purchasers looks positive. There are at least 5 that left positive feedback about that machine. I like it because of the handheld probes, and if I can turn it on longer, I wonder if I can use any tab thickness. Have you tried this type before? Just wondering if you think the welds would be inconsistent or if you experienced inconsistent welds with this type of machine.
Syonyk wrote:
robocam wrote:What do you all think of this welder?

http://www.ebay.com/itm/3-DAY-SALE-Batt ... Sw9mFWIsZd
No idea. It doesn't give anywhere near enough information that I'd be willing to purchase it. Single pulse? Double pulse? How long? How adjustable?

If it's "tap the foot pedal and it goes," you'll have radically inconsistent welds and burn through a few batteries.
Is this the 788 being referred to? Is there a way to use handheld probes? It would seem difficult to hold a huge battery to the machine.

http://www.ebay.com/itm/181922221370?_t ... EBIDX%3AIT
Yes, I think the 788H is the newer version of the 788+. You can wire up handheld probes if you want, but I haven't had to worry about it - I've just learned to build packs within it's constraints. I'm not building huge packs, though.

Syonyk   10 kW

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Re: 788 spot welder

Post by Syonyk » Mar 03 2016 2:47pm

robocam wrote:Yeah, it stays on as long as the switch is pressed. The ebay feedback from purchasers looks positive. There are at least 5 that left positive feedback about that machine. I like it because of the handheld probes, and if I can turn it on longer, I wonder if I can use any tab thickness. Have you tried this type before? Just wondering if you think the welds would be inconsistent or if you experienced inconsistent welds with this type of machine.
I haven't used one of that variety, but I don't see how that can produce consistent welds.
Battery packs, Sunkko Welders, and more. http://syonyk.blogspot.com/

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robocam   10 kW

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Re: 788 spot welder

Post by robocam » Mar 03 2016 5:47pm

Here's a video of it in action. The only difference is that this one has a thumb switch vs. the foot switch of the one on eBay. Maybe I could hook up a timer to the switch so that each time I activated it, it would turn on for the same set amount of time.

https://app.box.com/s/qjpwxw0jh7tjszfic ... 20062745/1

Also, is the 788 or this one from China better?

http://www.ebay.com/itm/220V-110V-Micro ... 2109020004

I also have a 170 amp welder at home. Could it be adapted for use with batteries?

http://www.harborfreight.com/170-amp-dc ... 68885.html
Syonyk wrote:
robocam wrote:Yeah, it stays on as long as the switch is pressed. The ebay feedback from purchasers looks positive. There are at least 5 that left positive feedback about that machine. I like it because of the handheld probes, and if I can turn it on longer, I wonder if I can use any tab thickness. Have you tried this type before? Just wondering if you think the welds would be inconsistent or if you experienced inconsistent welds with this type of machine.
I haven't used one of that variety, but I don't see how that can produce consistent welds.

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edrift.eu   1 W

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Re: 788 spot welder

Post by edrift.eu » Apr 30 2016 10:45am

I had some terrible problems with mu Sunkko 788+.

It does not work unless you have a 20A fuse (220V) and the CEE 7/7 plug (grounded High Amps europlug) is NOT rated for more then 16A so there is real catch 22. Ive taken it to an electronics lab in stockholm and they had every machine imaginable (except for a spotwelder) running with no problem. We tested Sunkko 788+ on several separated circuits with 16A fuses and switches but it would not start. It blew all fuses.

I would NOT recommenced it unless you can actually supply 20A and doin that with CEE 7/7 plug rated max 16A is not really smart either.

https://www.youtube.com/watch?v=U8F_KFbMEGQ

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Wheazel   10 kW

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Re: 788 spot welder

Post by Wheazel » May 01 2016 6:42am

edrift.eu wrote:I had some terrible problems with mu Sunkko 788+.

It does not work unless you have a 20A fuse (220V) and the CEE 7/7 plug (grounded High Amps europlug) is NOT rated for more then 16A so there is real catch 22. Ive taken it to an electronics lab in stockholm and they had every machine imaginable (except for a spotwelder) running with no problem. We tested Sunkko 788+ on several separated circuits with 16A fuses and switches but it would not start. It blew all fuses.

I would NOT recommenced it unless you can actually supply 20A and doin that with CEE 7/7 plug rated max 16A is not really smart either.

https://www.youtube.com/watch?v=U8F_KFbMEGQ
Its only the inrush current that is large.
As soon as you have an electrical installation that can handle it, it wont draw those currents while running.
Ive run mine from a 380V converter rated for 16 or 20amps, dont remember exactly.
The 16A rated plug is in no danger, as the inrush is brief. Not saying its a good construction, but it has served me well.
Nowadays I have a riba welder aswell.

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edrift.eu   1 W

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Re: 788 spot welder

Post by edrift.eu » May 01 2016 9:16am

Thanks for the response Wheazel!

I heard about "inrush current limiter" but is there any product i can use between the spotwelder and AC outlet to limit the inrush current? Or do need to build one?

WHich Ribe model are you using?

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Re: 788 spot welder

Post by BlueBand » Jul 15 2016 9:56pm

Hi try this to for Bed Time reading:-

https://en.wikipedia.org/wiki/Inrush_current_limiter

They cost £32.00 in the UK, but are only a few NTC's Caps and resistors so cost is very small.

Regards David

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Re: 788 spot welder

Post by Punx0r » Jul 16 2016 1:20pm

Can't remember if I mentioned this before, but I have a MIG welding on a 16A breaker that will occasionally trip when the transformer powers up (not when the arc strikes) when on the highest output. Running it on a standard 10m extension lead prevents this. With some experimentation this technique may work for this spot welders if the installation is marginal.

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Re: 788 spot welder

Post by cborn » Apr 06 2017 12:06am

Somewhat late, but I'll post this in case it helps others.

I just received my 788H (eBay, AUD $203 delivered to Australia), connected it in the kitchen (240VAC, 20Amp breaker), there is a thump when it turns on and the UPS's in the office on another circuit squeal in annoyance! I welded a few tabs, seems to work fine (on steel, not on the tinned copper protection circuit boards on the back on some 18650!).

I then opened it up and added one of these: http://au.rs-online.com/web/p/thermistors/5167760/
(Not bad, $3.92 and free delivery, ordered online Wednesday, delivered 9am Thursday)

I installed it internally in line with the active, just after the fuse.

Turned it on, no thump or squeals at all, smooth as can be!
Thermal camera showed it at 80C just after turn on, rapidly dropping to 70C

I then did a few more welds, didn't appear to be any change in quality.

Early days, but looking good.

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robocam   10 kW

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Re: 788 spot welder

Post by robocam » Apr 06 2017 12:26am

What is the thermister doing in the circuit? Do you know if the 709A would benefit from this?
cborn wrote:Somewhat late, but I'll post this in case it helps others.

I just received my 788H (eBay, AUD $203 delivered to Australia), connected it in the kitchen (240VAC, 20Amp breaker), there is a thump when it turns on and the UPS's in the office on another circuit squeal in annoyance! I welded a few tabs, seems to work fine (on steel, not on the tinned copper protection circuit boards on the back on some 18650!).

I then opened it up and added one of these: http://au.rs-online.com/web/p/thermistors/5167760/
(Not bad, $3.92 and free delivery, ordered online Wednesday, delivered 9am Thursday)

I installed it internally in line with the active, just after the fuse.

Turned it on, no thump or squeals at all, smooth as can be!
Thermal camera showed it at 80C just after turn on, rapidly dropping to 70C

I then did a few more welds, didn't appear to be any change in quality.

Early days, but looking good.

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Re: 788 spot welder

Post by Punx0r » Apr 06 2017 2:53am

It's a negative temperature coefficient resistor (resistance starts high when cold and drops as it heats up), so it works as an in-rush current limiter. It's great that such a simple mod made such a difference :D

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Re: 788 spot welder

Post by tomjasz » Apr 06 2017 12:48pm

cborn wrote:Somewhat late, but I'll post this in case it helps others.

I just received my 788H (eBay, AUD $203 delivered to Australia), connected it in the kitchen (240VAC, 20Amp breaker), there is a thump when it turns on and the UPS's in the office on another circuit squeal in annoyance! I welded a few tabs, seems to work fine (on steel, not on the tinned copper protection circuit boards on the back on some 18650!).

I then opened it up and added one of these: http://au.rs-online.com/web/p/thermistors/5167760/
(Not bad, $3.92 and free delivery, ordered online Wednesday, delivered 9am Thursday)

I installed it internally in line with the active, just after the fuse.

Turned it on, no thump or squeals at all, smooth as can be!
Thermal camera showed it at 80C just after turn on, rapidly dropping to 70C

I then did a few more welds, didn't appear to be any change in quality.

Early days, but looking good.
Great find! I think it might be the saving grace for these welders. But after all the issues I had...I'm staying with the arduino 12V. If I had another Sunnko, I'd definitely follow your lead! Well done!
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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robocam   10 kW

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Re: 788 spot welder

Post by robocam » Apr 06 2017 1:17pm

I'm trying to find a source in the US. In this list, which one would be a good match? I'm using a 220V 709A.

http://www.mouser.com/Circuit-Protectio ... gQodpSENLg

Also, how did you decide on a 50 ohm thermistor?

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robocam   10 kW

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Re: 788 spot welder

Post by robocam » Apr 06 2017 5:35pm

Would this work for the 220V Sunkko 709A? It's 0.5 ohm vs 50 ohms, so I'm not sure how that would affect things.

http://www.ebay.com/itm/Ametherm-AS35-0 ... 2012412672?

Here's the closest thing I can find. Is the 3A rating ok? It's a lot bigger at 16mm vs 5mm. I wonder what that means.

https://smile.amazon.com/NTC-47D-15-Cur ... or+limiter

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Re: 788 spot welder

Post by James Broadhurst » Apr 08 2017 2:28am

cborn wrote:I then opened it up and added one of these ...... (snip) ......... Early days, but looking good.
Well done!

I also have a 788H which I bought 5 months ago. It is junk and I have no possibility of getting my money back. The speed with which the repayment trapdoor snapped shut was a warning ignored.

The problem I have with your solution is that it requires me to open it up whereupon the utterly awful construction is revealed. Unless touching its innards has the same power as rubbing the genies lamp and being made a millionaire, I wouldn't touch this useless lump of excrement with a barge pole.

That opinion is in no way a reflection of the cunning and adept solution you offer.

They say a monkey could write the bible given enough time but would never be able to write the 788H manual.

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Re: 788 spot welder

Post by tomjasz » Apr 10 2017 1:29am

James Broadhurst wrote:
cborn wrote:I then opened it up and added one of these ...... (snip) ......... Early days, but looking good.
Well done!

I also have a 788H which I bought 5 months ago. It is junk and I have no possibility of getting my money back. The speed with which the repayment trapdoor snapped shut was a warning ignored.

The problem I have with your solution is that it requires me to open it up whereupon the utterly awful construction is revealed. Unless touching its innards has the same power as rubbing the genies lamp and being made a millionaire, I wouldn't touch this useless lump of excrement with a barge pole.

That opinion is in no way a reflection of the cunning and adept solution you offer.

They say a monkey could write the bible given enough time but would never be able to write the 788H manual.
I would say the same for all Sunnko welders. The simple design of the 12v Arduino malectric, and the original Riba(Jakov) are so much nicer. I only wish i had saved the probe mecanisim to retrofit. I did manage to sell the parts. And get a few dollars back.
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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robocam   10 kW

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Re: 788 spot welder

Post by robocam » Apr 10 2017 8:24pm

Can I bypass it once the unit is on? It's only there for the first turn on right?
Punx0r wrote:It's a negative temperature coefficient resistor (resistance starts high when cold and drops as it heats up), so it works as an in-rush current limiter. It's great that such a simple mod made such a difference :D

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Re: 788 spot welder

Post by James Broadhurst » Apr 30 2017 10:42am

tomjasz wrote:I would say the same for all Sunnko welders. The simple design of the 12v Arduino malectric, and the original Riba(Jakov) are so much nicer. I only wish i had saved the probe mecanisim to retrofit. I did manage to sell the parts. And get a few dollars back.
I concur about the Arduino malectrics.eu. It welded my pack using 0.15mm coil pure nickel easily with a 45Ahr 450ccw battery - 10msec pulse.

I was able to rescue something from the Sunnko debacle - the foot switch. The only thing that worked!

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Re: 788 spot welder

Post by tomjasz » May 01 2017 10:57pm

James Broadhurst wrote: I was able to rescue something from the Sunnko debacle - the foot switch. The only thing that worked!
Thanks for the laugh. I burst out laughing, as the foot switch is the only item i found of value as well!

All the best!

Tom
Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

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Re: 788 spot welder

Post by Britishguy4 » May 09 2017 8:13am

Hi guys

I'm trying to replace some batteries in a small medical transmitter by using a dremel, epoxy and spot welder. I've previously tried soldering the connection but this damages the batteries. I've attached the image of the transmitter.

I'm looking for a low cost spot welder to make the connection between tab and battery, any recommendations?

Thanks
Attachments
2017-05-09 14.12.11.jpg
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walko   1 µW

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Re: 788 spot welder

Post by walko » Sep 11 2017 5:35am

Hi friends... I have a 788H+ and I´m thinking about install a "remote soldering". was it tried yet?

Image

Image



this is accesory for 709. But I was thinking, maybe, it will work if I attach to actual head of 788 (where are the tips, with screws... if I remove screws, I can attach this).

Image

what do you think? will it work? I´m using 220v at working perfectly.

Of course, it must be used with FOOT PEDAL

thanks

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Re: 788 spot welder

Post by georget » Jul 15 2018 2:52am

here is a complete PCB for the Sunko and other Spot welders.
https://georgehobby.wordpress.com/2018/01/27/maxweldv2/

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