Thermal arc 130 gts repair

[chrismac]

Hi, I have been carrying out some tests on various components on this machine, I have the service manual and its very explanatory, I have located a problem with the figures which should be present in the Integrated Power Module (IPM),
First off the manual states that if any damage is present it should be replaced, well mine is cracked on the top but I carried on with the tests anyway to make sure one way or the other it was or was not damaged,

I now have now diodes which are not doing what they should and short circuits where there should not be,

How is this item made, does it have a resin poured onto it to seal it up? are they repairable? are they replaceable in a cost effective way.

any help would be much appreciated.

Chris

 

[zzr1200]

Close up macro type pictures of the IPM and faulty item/s would help being as we are all advising blind without seeing it...

 

[chrismac]

Hi Okay thanks for your comments,

here is some more info and the item in question, showing the cracked part it runs down and over the bottom corner,


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The tests I carried out were from the two sets of wires connected to the circuit board and the large electrical connection at the sides, here is what I did with the results,

No 1, Input section


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Here I checked the diodes between,

Terminal P(TB3) cathode and R(TB2) anode and got 001 on the meter both ways, ( damaged one?)
Terminal N(TB6) anode and R (TB1) cathode and got 446 one way and nil on the meter, ( a good one)

Check (SCRs) what ever they are, for short circuits

T, S(TB1) and P(TB3) 001 either way with meter
T, N(TB6) and S(TB1) - lead on S 389, + lead on S no reading, from manual: short circuits indicate faulty, open circuits indicate good device,

Check gates for resistance of approx. 40 Ohms between following,

K1 and GT1 on PCB1 nil on meter,
K2 and GT2 on PCB1 34 Ohms


No 2, Switching section,



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The switching section contains 2 IGBT transistors and 2 diodes check diodes between,

T, P cathode and Q anode= +lead on P and - lead on Q 345, reverse them 984, meter sits about 1300 normally
T, N anode and Q cathode= + lead on N and -lead on Q 345, reverse 1300

Select Ohms scale on the m/m and check resistance of the IGBTs gates between G1-E1 and G2-E2 these should read 9.1Khoms and do.

No 3, Output section,



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Check diodes between
T, DOUT cathode and MT 1 anode = 188 then reverse nil on meter (good)
T, DOUT cathode and MT 2 anode = 188 then reverse nil on meter (good)

No 4, Smart Link Triac section,


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Measure for 2 MOhms or greater between T, C and T, R 5.41Mhoms (good)
(they may act like charging a capacitor)

Measure the gate of the TRIAC for approx 35 Ohms between T1 and GT3= 36.80 Ohms (good)

No 5, Thermal shutdown,


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Check between TH 1 and TH 2 looking for approx 5KOhms, =5.76KOhms (good)

This is the wire connection end,


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I get continuity on all the wires to there corresponding soldered terminals but the first one the purple coloured one, I get no reading here.

Hope this is not too long winded, its taken me quite a while to type this little lot in but do relise that it is helpful if there is more info rather than less.

thanks Chris

 

[HughF]

Best get the dremel out

 

[mfletch]

You could try asking R-TECH they repair plasma cutters
http://www.r-techwelding.co.uk

 

[chrismac]

Thanks for the replies, I think I will hold off on the dremel for a day or 2.

Chris

 

[chrismac]

Well I have now got my welders fan running, I will have to investigate some more as I have no output,

Chris