contiweld 140 with a burned resistance

[rubysmit]

Hi,

I have a contiweld 140 with a burned resistance.
This resistor has a value of 8.8 ohms but I do not know if this is the correct value because it is completely burned , as shown in the picture.
The board code is W10E maybe someone has a drawing of this PCB so I can determine the resistance value.

Sincerely,
Ruben

 

[R Kraft]

Resistors don't usually burn out for no reason.
When you get a new resistor, check the board for a shorted zener or something similar.

 

[rubysmit]

I would also replace several parts. But these parts are not burned.
But how do I find out what the value is of the resistor?

Sincerely,
Ruben

 

[the snooper]

I would remove that resistor and check on the underside if any of the colours are visible, also resistors don't burn when the fail something else has failed causing the resistor to fail

 

[rubysmit]

The coding of the resistance is completely burned but he is not in two pieces. If I measure the resistance I get a value of 8.8 ohms.

 

[Wendelspanswick]

The coding of the resistance is completely burned but he is not in two pieces. If I measure the resistance I get a value of 8.8 ohms.

Preferred resistor values are 8.2 or 9.1 but 8.8 ohms is a really low value for a resistor.
If you can't determine the correct value I would plump for a mid range value and see what happens!

 

[rubysmit]

Preferred resistor values are 8.2 or 9.1 but 8.8 ohms is a really low value for a resistor.
If you can't determine the correct value I would plump for a mid range value and see what happens!

What seems to you a reasonable resistance value?

 

[mike 109444]

Is one end of the resistor and diode connected to the coil end of that relay ? As it could just be a current limiting resistor for the coil of the relay and the diode is there for surge protection. Might imply that relay coil is shorting.
Do a google for "relays in circuits" to see how the diode might be connected

 

[the snooper]

that circuit board looks the same as a murex trades mig 135 and the resistor in question is 30 ohms
below is the pcb diagram and here is the link to the manual with diagrams

 

[the snooper]

here is a bigger capture of the relevant area

 

[the snooper]

I would replace the capacitor and the 1n4007 diode aswell k1 is the relay

 

[R Kraft]

C7 being shorted would put about an amp of current through R1, about 30watts through a 1/2 watt resistor.

 

[rubysmit]

Thanks!
Today I replaced the resistor , diode and capacitor.
And the welder lives half.
The relay switches on when I press the torch button. And then there is current on the wire .
But the wire feed motor is not running and the timer functions do nothing.
So there is still a defective item.

 

[the snooper]

You will
Probably need to replace the transistor for the wire feed can't see the diagram ont phone it's too small

 

[rubysmit]

You will
Probably need to replace the transistor for the wire feed can't see the diagram ont phone it's too small

That will be the BDV64B I think.

 

[the snooper]

v24 is drive and v23 is brake

 

[rubysmit]

I'm going to order them!
When I have soldered the transistors on the PCB, I 'll let you know.

 

[rubysmit]

Today I have soldered the two transistors on the PCB.
But he still does nothing so it is another component.
Do you have any tips?

 

[R Kraft]

I suppose v21 could have burnt out, there was almost no resistance to limit current.