Lorch HT 180 AC DC : Fault code E3

[eddie49]

Hmmm, I am not sure.... I did not expect that either! I thought the error would still be there, implying that it was a false error and did not depend on the physical device.
Theoretically, it means the shunt really is faulty. I assume that you have had it loose in your hand and checked for fractures. You probably would need an accurate meter to check the resistance ( a few milliOhms? ), and we don't know what it should be.
Not knowing what assumptions the programmer made in his logic flow, there could still be a communication error, giving a "null" result now. Try power-up with a direct short across the X7 pins of the PCB.
The machine cannot be used, because without current feedback, the inverter control will not know how hard to drive the power transistors.

 

[Weldoradoo]

The shunt is one solid piece without any cracks. And my eyes are very good indeed.

 

[Weldoradoo]

But maybe its the wrong shunt? Too bad there is no part # anywhere. Would be nice to see a picture from another machine. How it should look like. And I would want to know the resistance value of the shunt from a machine without faults.

 

[Weldoradoo]

From a german forum I came in contact with a guy who owns a Wurth 180 Ac Dc welder. This is the same machine. But with a different housing. I could ask him what the resistance is at the plug that goes into the Eprom at X7.

 

[Weldoradoo]

Should I order a new shunt ?

 

[eddie49]

The shunt is an important part of the feedback loop that controls the power level of the inverter. As such, it is possible that the self-test checks it carefully, even though this would need a test circuit capable of measuring milliOhms. So it is possible that the E3 error is genuine, and despite appearances, the shunt is defective.

- Try power-up with a direct short across the X7 pins of the PCB. Does the fault code change or disappear?
- Have you got or can you borrow a meter that can measure milliOhms?
- Put the shunt in a circuit such as a 12v car battery, a 60W 12v H4 bulb, measure the milliVolts developed across the shunt that corresponds to this 5 Amp current - maybe 5 mV.
Failing that, order a new one. If it is very expensive, start with a cheap 200A "test replacement" from eBay:

FL19 Inverter Welder Diverter 100/200/300A 75mV Copper Material DC Current Shunt | eBay

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[Weldoradoo]

Its not really expensive. 50 incl shipment.

 

[Weldoradoo]

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[Weldoradoo]

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[Weldoradoo]

I dont have a device to measure in the mV range.

 

[Jim Davey]

Most multimeters have a millivolt range. Even cheap really ones should be able to do that function. You may need to manually select the correct range.

 

[Weldoradoo]

Ok I will try...

 

[Weldoradoo]

A Lorch service guy told me I should change the wiring (from shunt to X7 at mapro). I only "beeped" the cables for continuity. But a minor crack could change the ohm resistance

 

[Weldoradoo]

Thats relatively easy.

 

[Weldoradoo]

Try power-up with a direct short across the X7 pins of the PCB.

What would I simulate with that?

 

[Jan-DIY]

Tbh do what he mentioned or take yourself some time to dig into main principles of electronics.
If you think about what @eddie49 wrote it is quite simple.
Difference between OC and CC.

 

[Weldoradoo]

Please dont use technical acronyms. I am trying to learn more but its hard to look things up if I dont know what OC or CC stands for. I know AC DC and V= I.R :-p

 

[Seadog]

What would I simulate with that?

A piece of wire.

 

[Jan-DIY]

OC- open circuit is what you discovered while disconnecting shunt.
CC- closed circuit is when you get a bridge on X7
Iam out here because you’re lacking of basics and I don’t like rude conversations.

Cheers.

 

[Weldoradoo]

Ok. I was planning to just use a piece of wire yes. But didnt know what the pcb could do with a cc situation.