Searching for MIG welder replacement control board

[eagle1109]

Hi,

I have this machine and searching for a control board replacement, searched on Google, eBay .. etc. Didn't find it. I even contacted the company and they didn't respond.

Model name:
Art. 581 Bravo synergic MIG 3840/T

The machine is discontinued.

This is the machine:

 

[D.A.(Tony)Stewart]

slim changes ... good luck https://www.manualslib.com/manual/799428/Bravo-Synergic-Mig-4540-T.html?page=16#manual

 

[eagle1109]

This is the control board:

Will it be the same ? I hope it has the same connectors.

--- Updated Nov 18, 2023 ---

Yep, based on the model you provided I found good results on Google, and I checked this website:
https://www.layva.com.uy/productos/....2443.2497&zona=0&order=3&mo=1&ps=50&pagina=1

I think it's the same board, this is a picture of the two boards, the one I have and the one on the website:

--- Updated Nov 19, 2023 ---

I have another question, are there cheaper alternatives for these Italian welders ?

I'm thinking that there could Chinese than can perform similarly and at the same time have good priced replacement parts.

 

[D.A.(Tony)Stewart]

bad caps

 

[eagle1109]

Yep, I detected those. I hope they are the only broken parts.

This Darlington transistor got fried.

This LM7805 got snapped.

The only two capacitors I check broken are these:

This 1000uF 50V cap, the two next to it I guess are ok.

And this 470uF 25V

I ordered the parts from Aliexpress.

--- Updated Nov 19, 2023 ---

There are two machines: one with a broken board which is this one and hoping to fix it, the second welder doesn't have a board.

That's why I'm searching for another board. Which I found one in the link I posted in #3, but it's very expensive $912.

I told my colleague that instead of buying this expensive board, they can buy a new cheaper welder with like $360 from Amazon or any local distributer.

But also the question I'm thinking of is why that control board is so expensive ? as the machine is relatively old and also discontinued.

 

[D.A.(Tony)Stewart]

I hope you ordered low ESR caps

 

[eagle1109]

I think I didn't, I ordered from this store in Aliexpress:
https://www.aliexpress.com/item/100...order_list.order_list_main.118.196f1802V1uWg0

But I didn't that because I think also the ones on the control board are ordinary capacitors.

 

[D.A.(Tony)Stewart]

when you exceed the ripple current rating long enough, they outgas like this.

 

[eagle1109]

OK, I checked the brand name which is ELNA. I searched about it in Aliexpress and found that most of them are for audio application.

I found these very similar to the ones on the board and have the same letters:
https://www.aliexpress.com/item/100...id=2023111908075212677738417943440002832479_8

I think I'm going to cancel the ones I ordered.

 

[betwixt]

I would stay with the ones you ordered. Neither type specify ESR and are probably the same. If you want guaranteed low ESR you need to buy from a more reputable source that can trace them back to the manufacturer. Using standard types will work, they may not last as long but they will still function. For best results you need ones specifically rated for low ESR and preferably 105C temperature (most are 85C). Reputable manufacturers quote expected lifetimes in thousands of hours and give you graphs of impedance against frequency.

Brian.

 

[D.A.(Tony)Stewart]

ELNA carries a wide range of 1000uF 50V cap that include both general purpose and low ESR. Unless you pay more for low ESR types and know exact part numbers, assume they are general purpose. But at least they are a good brand .

AL ELECTROLYTIC CAPACITORS | TY-COMPAS | TAIYO YUDEN CO., LTD. for NA

You can search for AL ELECTROLYTIC CAPACITORS of TAIYO YUDEN from characteristics and specifications.We have various kinds of products such as conductive polymer hybrids, low impedance · high ripple products, long life products etc. This Page is for North America

ds.yuden.co.jp

 

[eagle1109]

I would stay with the ones you ordered. Neither type specify ESR and are probably the same.

Yep, I thought so.

Actually what happened and why those parts got broken, is that as my colleague told me that when they received the machines from the previous training institution, the internal mains were connected to 220V, and the workshop main at the college is 380V.

the trainers at the workshop directly connected the machine plug to the workshop mains without knowing about the power setting, and he told me that they heard a sound of small electrical explosions.

I checked the board and found those parts broken.

Even I would checked the machine manual for the electrical connection for the mains when I solder the new parts to prevent frying the board again.

 

[D.A.(Tony)Stewart]

now you tell us.

 

[eagle1109]

Yep, that's what happened.

 

[eagle1109]

Hi,

I just want to be sure if the current wiring is correct. This is what they told me that it's what they corrected after the board broke:

According to the wiring in the manual, I think the wire marked with the yellow arrow is not correct.

So, if they chose the 380V setting, then there shouldn't be any wire connected to the 230V output. Am I correct here ?

 

[eagle1109]

Hi guys I just received the parts:

I removed the broken parts and soldered the new ones, then I did a test with the DMM to know if things are OK.

No shorts, mostly but found a short on the LM7805, marked with 2 red lines. Between the OUTPUT and GND it measures 15ohms. Could that be a problem ?

 

[D.A.(Tony)Stewart]

ELNA 1mF 50V is rated for 1400 mA rms https://datasheet.lcsc.com/lcsc/2105241211_ELNA-RA3-25V222MI6-_C399582.pdf

That's a very good number, but 3.3 mF is better but bigger size.

 

[eagle1109]

ELNA 1mF 50V is rated for 1400 mA rms https://datasheet.lcsc.com/lcsc/2105241211_ELNA-RA3-25V222MI6-_C399582.pdf

That's a very good number, but 3.3 mF is better but bigger size.

What do you mean here ? do you mean the reason for the low resistance across the LM7805 OUTPUT and GND is the capacitor resistance ?

Because I measured the low resistance before soldering the LM7805, and I noticed the low resistance is still after soldering the LM7805.

 

[BradtheRad]

Because I measured the low resistance before soldering the LM7805, and I noticed the low resistance is still after soldering the LM7805.

You read 15 ohms between output & ground before installing it? It might not matter if your meter applies current from ground to output. However if current is flowing from output to ground then that sounds like 1/3 Ampere being wasted. Almost 2W. Enough to generate heat to burn your finger. Add the load to that and it might shut down which is a safety feature of 7800 series regulators. Still you ought to test the regulator's performance out of circuit.

 

[eagle1109]

It might not matter if your meter applies current from ground to output. However if current is flowing from output to ground then that sounds like 1/3 Ampere being wasted.

You mean using the ohmmeter or continuity mode ?

After LM7805 is soldered, I tested it with the continuity mode, the +ve on the OUTPUT and -ve on GND and measured 15ohm and the same result switching the DMM probes.

Still you ought to test the regulator's performance out of circuit.

It's a new one from the warehouse. I tested the LM7805 before soldering it and it measured OK, meaning no shorts between the pins.