Powermax 1000 dead IGBT Q7 advice + help identifying parts needed

Tue, 31 Aug 2021 08:59:42 GMT

go to see Welding Machine for Powermax 1000 dead IGBT Q7 advice + help identifying parts needed

This is my first post, so hey everyone!I got a defective powermax 1000 to repair and need some help identifying one or two odd components that are too far gone to be identified.My background: hobbyist welder and EE (still in education, 6th year) from GermanyTools&Resources available: Multimeter, LCR-Meter, Soldering Iron, Oscilloscope, Lab Power Supply, ...The only description I initially got is "it broke, won't turn on" - so I took her apart and it looks like I got myself a burnt IBGT Q7. - Please see below photos.Everything apart from the damage seems to be in good condition, seems like the unit didn't get that much use. Was connected for 3x400V (32A breaker) in Germany.It seems to be very similar to the damage in this thread, the damage is just a little more aggressive on this unit. And this seems to be a "Gen 2" PCB.I managed to clean up all the charring and made a list of all evident damageesignatorStateTypeValue/LabelCharacteristicsQ71/2 defectiveIGBT2MBI200S-120Dual 1200V 200A, 24nF, #2 configured G-E always-onQ6possible damage, needs more testingIGBT2MBI100PC-140Dual 1400V 100A, 10nFL2functional, light damageInductorn/An/AR98burnt, arc damageResistorBrown-Black-Gold-Gold1 Ohm 5%R99burnt, arc damageResistorRed-Black-Black-Yellow-Brown2M Ohm 1%R100burnt, arc damageResistorRed-Black-Black-Yellow-Brown2M Ohm 1%R101possible damageResistorRed-Black-Black-Yellow-Brown2M Ohm 1%R66burntResistorBrown-Black-Black-Gold10 Ohm 5%R67burntResistorBrown-Black-Black-Gold10 Ohm 5%R28burntResistorRed-Violet-Black-Gold27 Ohm 5%R20burnt, arc damageResistorViolet-Green-Silver-Gold0.75 Ohm 5%R??burnt, arc damageResistorYellow?/Gold?-?-Black-BrownORBrown-Black-?-Yellow?/Gold?Q2case exploded, 0.3 Ohm short on pin 2-3, open circuit on 1-2, 1-3Transistor/BJT?…12 // -140My plan is to first tackle all the visible damage and then function-check all the components in the PFC section for invisible damage and replace if necessary.This machine has quite some power to it, so I am going to take precautions and double-check things. If something goes electrically wrong at this kind of power, it makes for a very bad day.For a start, I have ordered a new PFC IGBT (was around 45€) and may order a new Q6 IGBT next as some have suggested in the old thread. All the other components in the PFC section look to be standard off-the-shelf parts that can easily be sourced if only I could identify them.I have also checked the input and output diodes and all other IGBTs and have found no further damage there.It would be very nice if someone knew what Q2 (last image) or the anonymous resistor (see red circle in photo) was or could provide a photo of it in non-defective state or give any further advice.I will happily post my solution to this damage (if I get her up and running again, that is) in exchange.
Reply:I'm guessing you already found this thread...  https://weldingweb.com/vbb/showthread.ph...sehold-breaker
Reply:Yes I read that one, but thanks anyways. Unfortunately, neither Q2 nor the badly burnt resistor (red circle) can be identified from the photos in that thread. Was hoping someone with experience in these units or the same model of plasma cutter is still around and could have a quick look.
Reply:Yeah, I know I looked though the pics.... you might try PM'ing the op on that one... haven't seen him around but you never know...  Quite a few guys have the 1000 so maybe someone will pop in with help.
Reply:A quick update: The OP replied but unfortunately has no more info on the unit since he got rid of it back then.I also found this: https://www.cnczone.com/forums/hyper...nyone-can.html and sent a PM to the OP there.In the meantime, I had a quick look at the circuit and it seems actually two sections have failed:Section 1 - Flyback System Power SupplyThe blown Q2 seems to have been the main switcher for the nearby transformer T1 which then generates all the "harmless" logic supply voltage rails for the rest of the board (it's basically more or less a standard SMPS). It operates off the intermediate voltage rail, V_BUS.Section 2 - PFC/Intermediate Voltage Rail (V_BUS)The IGBT Q7 is used as a switcher and diode combination (thats why E1 and G1 of the dual package have been shorted during manufacturing, doing this gets you a powerful, relatively low loss diode) and together with the massive choke in the back right section of the unit forms a boost converter that is generating another (very high) voltage rail labeled V_BUS. V_BUS is 750VDC +/-15% according to the service manual and is backed by the two beefy capacitors. It is used as the intermediate voltage for the output inverter and other parts of the system, the Flyback System Power Supply, Section 1.Initial thoughtsAs to what happened to my unit, I summarize:That a powerful arc that has formed between the E1 terminal (which hardwired to the rectified mains negative) and the rectified mains positive present on J9 during operation some time during the failure.That a (smaller) arc has also formed between the rectified mains positive (J9) and V_BUS positive terminal, terminal C1, of the IGBT Q7.That the Q7 IGBT failed. The E1-C1 IGBT (the one configured as a diode) is definitely damaged, tests with the second IGBT in the package, C2E2 have been inconclusive to this point. The arc may have been the reason or a symptom of Q7 failing, I have not come to a conclusion about this yet.That the failure also propagated through R98 into the drive circuitry.That the failure also propagated through the gate/emitter connector J8 into the drive circuitry.This means that the driver ICs in the section may be damaged as well.I have yet to find a plausible explanation for all this to happen. V_BUS would not have far exceeded the allowed limits without the protection tripping and preventing the unit from damage.Maybe there was EMI present, maybe a massive voltage excursion / HV transient on the mains made its way through the input filters?There could have also been conductive dust present.
Reply:Good News!Today I started off by desoldering all the dead components from the board and putting them in individual labeled boxes for further reference. Then came the hardest part: identifying the unknown components.IGBT Q2After putting some more thought into the components, I took some dimensions and finally made a guess as to what Q2 must have been. Measuring its physical size with a caliper, we have a TO3PF case. This case is typical for MOSFETs and also IGBTs. So with the bits of part number that were left ant knowing that it runs off the intermediate voltage of 750V, my guess was it could have been a 1400V 12A MOSFET or IGBT.I did a bit of research online and after a couple of tries, a magic part number popped up: 1MB12-140, a 1400V 12A IGBT made by Fuji Electric Co., the same MFG as with the Q7 IGBT!All available photos matched, and also the little "B" letter at the bottom left corner and the mold marks align.To try and confirm this some more, I then googled "1MB12-140 Hypertherm" and found this thread: https://tractorpoint.com/forum/weldi...erm-600--.html at tractorpoint. Seems that same device is also used in the Powermax 600. Makes perfect sense to me for Hypertherm to reuse their logic power supply in all devices they make... why reinvent the wheel every time. So yeah, dead part #1 identified!A quick search at digikey returned no results for the 1MB12-140 and all available listings on eBay or other places show ridiculous prices of 30-40€ for this part (I would say it is worth maybe 5-10€), but I am sure that I will be able to replace it with something much better (in terms of specs and price) if required with not much effort.Anonymous burnt resistor = R30So after sucking off this one, it revealed the label underneath: R30. I put what was left of it under the microscope and identified: Yellow - UNKOWN (maybe Green or Gray) - UNKNOWN (maybe Gray) - Black - Brown which makes this a 4xx Ohm, 1% resistor. The xx is yet to be figured out.After further investigation, I found that R30 is used in the over current protection circuitry of the DC-DC driver IC U5 (marking FA13844). It forms a low pass filter for the current feedback signal derived from the shunt resistor R20 (0.75 Ohm) together with C36 (2.2nF).This is very good news! This means that the exact value of R30 does not matter all that much as long as it is in the right ball park (of 4xx Ohm). I had a look at the datasheet for the FA13844 and the reference design mentioned there uses 1k Ohm and a 100pF capacitor which gives about 1.6MHz cut-off frequency. Hypertherm used 2.2nF for C36 and with say 470 Ohm, this would give 154kHz cut-off frequency. According to the datasheet, U5 can operate from 10..500kHz so it all comes down to what frequency U5 is set to operate the boost converter at. I will have a look at the circuit around U5 to determine the design frequency and select R30 accordingly, but in summary 470 Ohm should be just fine.Next step is obviously to check for invisible damage in the whole PFC and supply section of which I am sure there will be some and then place some orders for parts. My replacement IGBT for Q7 has already arrived. So far, I would estimate parts will be about 50-60€ if I find no further major damage.Some over at the other Powermax 1000 thread at weldingweb have suggested to also replace the inverter IGBT, so I guess this would be something to double-check (or maybe just replace it anyways as a precaution).Will keep you posted!
Reply:The part number for Q2 maybee facing the heat sink. Unscrew it and check.The resistors are precision so they use fourth band multiplier.
Reply:In my experience, When L2 , and R98 blow. There has been a failure in the PFC (boost ) circuit.The failure dominoes all across the pcb.The repair  has always been both IGBT blocks and the power pcb. Replace them.In the beginning People tried to just replace the PFC IGBT and the circuit pcb, only to have the main inverter IGBT blow.Even if it tested good with an IGBT tester. When I saw this failure, all most all of them had single phase 230 volt plugs on them.Your power pcb should have tubular resisters all around the large buss caps.Good luck on your repair attempt. Be prepared for it to blow again.
Reply:Good news and perhaps my final post on the Powermax!The summary is I checked 45 or so and replaced 20 or so components on the PCB. I just made a couple of test cuts in 8mm flat stock at 50A setting and she seems to work just fine. Will have to do more extensive testing to confirm everything holds but still.Due to the extent of my testing I will not comment on it in detail but only summarize.Below you find a table of each and every component I checked and/or replaced and some small comments:BOLD RED means the component was replaced because it was defectiveBOLD BLACK means the component was replaced but for other reasons than a defectNORMAL FONT means the component was checked or otherwise found to be intactDesignatorState/CommentTypeValue/LabelCharacteristicsReplacementCostQ71/2 defectiveIGBT2MBI200S-120Dual 1200V 200A, 24nF, #2 configured always-on2MBI200S-120-50 45,00€Q6likely damaged, driver U8 is blownIGBT2MBI100PC-140Dual 1400V 100A, 10nF2MBI100PC-140 161,64€L2functional, light damageInductorn/An/AR98burnt, arc damageResistorBrown-Black-Gold-Gold1 Ohm 5% 1WROX1SJ1R0 0,31€R99burnt, arc damageResistorRed-Black-Black-Yellow-Brown2M Ohm 1% 2W2x ROX2SJ1M0 0,48€R100burnt, arc damageResistorRed-Black-Black-Yellow-Brown2M Ohm 1% 2W2x ROX2SJ1M0 0,48€R101possible damageResistorRed-Black-Black-Yellow-Brown2M Ohm 1% 2W2x ROX2SJ1M0 0,48€R66burntResistorBrown-Black-Black-Gold10 Ohm 5% 1WROX1SJ10R 0,31€R67burntResistorBrown-Black-Black-Gold10 Ohm 5% 1WROX1SJ10R 0,31€R28burntResistorRed-Violet-Black-Gold27 Ohm 5% 0.5WROX05SJ27R‎ 0,17€R20burnt, arc damageResistorViolet-Green-Silver-Gold0.75 Ohm 5% 1WRR01JR75TB 0,28€R30burnt, arc damageResistorYellow-Green??/Gray??-Gray?-Black-Brown4xx Ohm 1% 1/2W (Meas 220k?)ROX05SJ470R 0,17€Q2case exploded, 0.3 Ohm short on pin 2-3, oc on 1-2, 1-3, replacing with similar type IXYH10N170CIGBT1MB12-1401400V 12A, 2nF, configuration GCE, TO3PFIXYH10N170C‎ 7,29€U5case cracked, original unavailable, using similar UC3844N as replacement, requires adjusting R27 and C16ICFA13844 D3701CMOS current mode control IC for DC-DC conv.UC3844N 1,40€R27out-of-circuit test: ok, needs to be changed due to U5 replacementResistorRed-Black-Black-Yellow-Brown2M Ohm 1% 2W680k 0,48€C16out-of-circuit test: ok (11.9 uF, ESR: 1.9Ohms), needs to be changed due to U5 replacementCapacitor12µF 63V 105°C LXY12µF, 63V, 105°C, Nippon LXY series100µF 63V 105°C Nippon LXZ 0,50€C36looks ok, double check!Capacitor2n2J1002.2nF 5%, 100V? PlasticQ3looks ok, tests ok, replacing as a precautionBJTD44H8NPN 60V, 10AD44H8 0,90€Q4looks ok, tests ok, replacing as a precautionBJTD45H11PNP -80V, 10AD45H11 1,00€U10in-circuit test: suspicious, out-of-circuit test: okICA3120V2.5A peak IGBT-BJT Output Optocoupler 630VHCNW3120 4,06€U8in-circuit test: suspicious, out-of-circuit test: output short groundICHCNW31202.5A peak IGBT-BJT Output Optocoupler 1414VHCNW3120 4,06€R84in-circuit test: suspicious, out-of-circuit test: failed openResistorBrown-Black-Black-Gold10 Ohm 5% 1WROX1SJ10R 0,31€R83in-circuit test: okResistorGreen-Blue-Gold-Gold5.6 Ohm 5%R??in-circuit test: okResistorBrown-Black-Red-Gold1k Ohm 5%R96in-circuit test: okResistorBrown-Black-Gold-Gold1 Ohm 5%C53out-of-circuit test: okCapacitor105 C5K1µFU11out-of-circuit test: ok, replacing as a precautionICTL780-05C1.5A +5V POSITIVE VOLTAGE REGULATORL7805CVD15in-circuit test: okTVS Diode1N6280A24V 45A suppressor, 1.5kW capableD17in-circuit test: okTVS Diode1N62xxxR9in-circuit test: okResistorBrown-Black-Red-Gold1k Ohm 5%D2in-circuit test: okDiodeMUR4604A 600V rectifier diodeD3in-circuit test: okDiodeMUR4604A 600V rectifier diodeD11in-circuit test: okZener Diode1N52263.3V 500mWR68in-circuit test: okResistorBrown-Black-Black-Gold10 Ohm 5% 1WR87in-circuit test: okResistorBrown-Black-Red-Gold1k Ohm 5%R56in-circuit test: okResistor3.9Ohm J3.9 Ohm 5%C10out-of-circuit test: okCapacitor.068K160068nF 1600V MKPD6in-circuit test: okZener DiodeBYV26GAvalanche Diode, 1400V 1.05AR19in-circuit test: okResistorBrown-Green-Orange-Gold15k Ohm 5%C23test skippedCapacitor.1 400100nF 400V MKPD30in-circuit test: okZener DiodeBYV26GAvalanche Diode, 1400V 1.05AC36test skippedCapacitor2n2J1002.2nF 5% 100VU9in-circuit test: okICHCNW31202.5A peak IGBT-BJT Output Optocoupler 1414VU6in-circuit test: VAO/VSENSE feedback voltage wrong, out-of-circuit test: VSENSE pin abnormal impedanceICUC3854BNAdvanced High-Power Factor PreregulatorUC3854BN 4,41€D12out-of-circuit test: okDiodeUF…While checking, I drew some mockup schematics of the sections of the PCB that had damage in them to better understand. I would be willing to post them here but am unsure if this is ok with Hypertherm.Due to the unavailability of high cost of some components I substituted some suitable replacements. This in turn meant that some parts of the circuit had to be redesigned, especially with U5 where the startup-resistor  value was lowered and the buffer capacitor needed to be of higher value to prevent erratic startups. This in turn means that the unit startup time now is about five seconds.R30 was replaced by a 470 Ohm resistor as described before.All parts except the two main IGBTs are available from Digikey. For the inverter and PFC IGBT I sourced the original part since I could not find a replacement with the same mounting post dimensions and suitable characteristics on digikey. This should however not make that much of a price difference and saves me the hassle of possibly having to redesign the drive circuitry to accomodate for the new parts.After all this was done I did a quick power up and then carefully re-coated the entire board with spray-can type 85kV/mm dielectric strength conformal coating to prevent any metal dust from shorting out things in the future.There was also a deep cut in the work lead so I cut off a small section of it and reterminated it using a 10-16mm2 cable shoe.I then performed all tests from the official Hypertem Maintenance Manual and to my surprise it seems all have passed.One final word of warning: please do not attempt this repair if you are not sure what you are doing. There is 750Vdc buffered by capacitors of substantial power as well as rectified mains present in the unit, both can easily kill or severely injure you!Thats it so far. Thank you for your support and I will report back in a while if it held up!