Invertec V140-S, need PWM circuit and resistor R48 value

[welder]

Hi dear technicians. Does anyone have a wiring/circuit diagram of PWM module at Invertec V140-S? S?veral weeks ago i receive this inverter with completely burnt out power module - six IGBT's (HGTP12N60) and two diodes (STTH12R06) has destroyed. Now I has finish with recover them and the gate pulses are correct, but ... When try to ignite arc the welding current is extremely high (around 150...155 A!) and no output current control from potentiometer. The potentiometer, output current sensor (shunt) and 8-wire cable between front control board and inverter board are correct. Something in PWM module make me crazy. In first place the device has previous attempts to repair from someone else and I'm not 100% sure in IC component type and placing: U1=LM324N, U2=LM393N, U3=TDA1060, U4=LM324N and U5=LM358N. That's correct? And second - the original resistor (R48) in red circle position is completely crumbles to pieces from rust and colour code are missing. I try to measure his remains and got as result around 220k. Also replaced, but again no 100% sure in this value! The IC's nr. 1, 2, 4 and 5 has also replaced (easy, adaptor socket), but no difference in problem status. The diodes and transistors in module is measured too and not damaged. I suspect R48 is with incorrect value, but no circuit diagram of PWM module. Does anyone have any high resolution photo of this PWM module or schematic diagram with component values?

?

This is the device:

 

PS: I have service manual, but there is no PWM/control circuit with any component values.

Thank's in advance!

Editat Septembrie 20, 2016 de welder

[miron1947]

http://www.digikey.com/us/en/mkt/6-band-resistors.html

[em2007]

http://www.digikey.com/us/en/mkt/6-band-resistors.html

Dl. Miron, nu codul culorilor e problema lui, il cunoaste bine, nu e incepator, e depanator de echipamente Lincoln.

Vrea sa stie daca valoarea de 220k pe care a montat-o el in locul celei originale deteriorate e corecta.

[cavit]

 I also stongly suspect that 220k in wrong because even line voltage al 500v can not destoy a 220 k ohm resistor because it can not generate enough current and power, and for 500 is needed a large clearance on PCB at least 1cm.

 

 Unfortunately i have no photo or diagram of this, but if your ptoto is an undamaged module you still can get the colours on resistor by processing that image.

 

 Another way to guess that value is to reveal it-s relation whith that lm 324, it seem that resistor belongs whith it, i solved many cases in this way.

 

 Is most probable that resistor powers lm 324, if it was shorted the resistor is destroyed, but it can by an output or a kind of sensing shunt, or a spike supressing filter at around 1k ohm.

 

 If is a spike supressor shunts and tracks on force PCB must be checked.

Editat Septembrie 21, 2016 de cavit

[gsabac]

Nota: Valoarea de 220K nu se poate arde in circuit. Poate valoarea este mult mai mica.

Curatati resturile de vopsea si masurati rezistenta intre terminale si zona rezistiva cu carbon,

 pentru a estima valoarea initiala.

 

Note: The value of 220K resistance can not the burn. Maybe it is value much lower.

Clean residues paint and measure resistance between terminals and carbon.

What is the value?

@gsabac

Editat Septembrie 21, 2016 de gsabac

[em2007]

In poza se vede rezistenta originala.

Am gasit-o mai greu prin vechile computere, poza e din 2004, cand am reparat ultima data o placa identica.

 

 

Valoarea e 220k

 

Nu ea e vinovata de defectiune.

 

Poate fi vinovat reglajul prost al limitarii de curent.

 

De verificat trimmpot-ul de langa placuta.

[cavit]

 220 k de atita este, o fi fost murdara cu praf de ala negru care  s-a umezit si uscat pe ea dupa aceea

[em2007]

... Another way to guess that value is to reveal it-s relation whith that lm 324,....

 Agree. In my opinion, this is the best way.

I always do so unconditionally in similar situations.