trying to repair arc tig 110 inverter

[bensalf]

hi everyone,
this is my first post since joining, i am trying to repair my brothers clarke arc tig 110 inverter welder.(he's the welder i'm the electrician)
there is a resistor burnt up on the circuit board, and i need to know its value so i can replace it. its too badly burnt to read any colour codes, and its labled as R9 on the board.
if anyone has one in pieces, could you possibly read me the colour bands so i may be able to get a replacement.
the clarke website has a diagram but the circuit board does not list the individual parts,
i'll try to upload some pictures.

this is welder opened up

 

[the snooper]

they are known for being hard to repair
you also have to think what caused the resister to burn in the first place

 

[bensalf]

t

he resistor fits where the end of the red straw is
the blue wire solders in front of the resistor

 

[bensalf]

yep, thanks " the snooper" i realise something else could be wrong, but for the sake of possibly a couple of quid, i could try a new resistor.

its broke in half and burnt up.

 

[the snooper]

have you tried measuring both halfs with a meter just to see what you get.

have you also tried mailing clarke for the value of the part

 

[bensalf]

resistor is too badly burnt to get any readings, its open circuit all the way to the end.
so i unwound approx one coil and measured the resistance which was about 8.8 ohms ,counted coils with magnifying glass to approx 35, which gives a very approximate 300 ohms.
so maybe a trip to maplins, to get an equivelent.
e mailed clarke technical, say circuit board is not made anymore, so cannot give value of resistor.
but they say problem may be a runawy power transistor, caused the burn out.
ill see if the resistor is availlable
thanks for your help.
stu.

 

[the snooper]

it may be worth removing the transistors and if your meter has it do the hfe test on them to try and find any bad ones

it appears to be on the power supply side so worth testing what ever you can even the rectifier you may get some clues

 

[bensalf]

yep cheers snooper, may dive a little deeper if resistor dos'nt work
strange response from clarke as the welder is still available at machine mart,
albeit limited stock.


£179.98ex. VAT
£215.98inc.VAT

product: 010112205
Clarke Arc / Tig 110 Power Inverter

A high quality power inverter that delivers regulated DC power for superior quality ARC welding. Electronically controlled output also facilitates smooth and precise TIG welding. Precision power […] can be Tig welded without risk of causing damage or warping.Limited stock, please call 0844 880 1250 for availability.

 

[the snooper]

if you just replace the resistor it will just burn out again they are designed for a certain wattage and that resistor has obviously had more then its designed for, have you traced the pcb to find what its connected to both ends ?

 

[Welderfix UK]

I realise this is a super old thread but for the sake of completenes (and if anybody else needs to know for future reference) that is the soft start resistor and it is 220R.

I know because we have just repaired one of these

Edited to add: the main converter FETS were also dead and some zeners on the drive circuit.