IGBT replacement - Page 1
Forum section: electronics / repair

author: D_Alekov
author_rank: Newbie
timestamp: December 04, 2023, 08:31:52 pm
content: Hi guys, I'm repairing a welding machine which has 12 blown IGBTs in the power supply. The blown IGBTs are no longer available and has a replacement part that has lower power dissipation. The original IGBT is SGP30N60HS (250w) and the replacement is IGP30N60H3 (187w). Is there a problem to change with the replacement part or I have to search with higher power dissapation

author: Slh
author_rank: Regular Contributor
timestamp: December 04, 2023, 08:54:33 pm
content: That's a lot of damage. 12 igbts must have made a bit of a mess.At first glance the new one looks like it might have lower losses (faster switching and lower forward voltage).I presume you've checked the rest of the circuit for damage? I often find that, when the switches die, the gate drive circuits also go to silicon heaven.

author: Zenith
author_rank: Frequent Contributor
timestamp: December 04, 2023, 11:34:59 pm
content: You can buy those IGBTs for a price.https://www.donberg.co.uk/catalogue/igbt_mosfet_rfuhf-power_modules/sgp30n60hs.htmlI've never dealt with them but they seem reputable. There are no doubt other sources. Ebay is notorious for fake IGBTs.That must be a beast of a welding machine with 12 IGBTs.Is it worth repairing? At £100 a pop for a set of IGBTs, experimenting and failing might prove expensive. I'd be concerned that all 12 had failed. Do you have a service manual for it? I've repaired a couple of inverter welders, both 130A with just two IGBTs. In neither case had the IGBTs failed. One had a bad solder joint and with the other, a thermistor in the pre-charge circuit was burned outAs to whether IGP30N60H3 is a suitable substitute, it depends on the heatsinking and thermal protection built in. The original IGBT might have been overspecified. Still at around £45 a set, experimenting could become expensive.

author: D_Alekov
author_rank: Newbie
timestamp: December 05, 2023, 09:02:08 am
content: Аctually they are two identical PCBs with 12 IGBTs each, they all be replaced but the original IGBTs cannot be found original. I have already ordered from 2 vendors and they are fake.Transistor tester finds out they are N-MOS. I'm writing here to ask the more knowledgeable if this replacement is suitable. My only concern is the dissipation power

author: D_Alekov
author_rank: Newbie
timestamp: December 09, 2023, 12:08:46 pm
content: Please help, I don't know what to do

author: CaptDon
author_rank: Super Contributor
timestamp: December 09, 2023, 03:17:57 pm
content: Since they are insulated gate some transistor testers may assume they are nmos fets? Possibly they are not fake?

author: Zenith
author_rank: Frequent Contributor
timestamp: December 09, 2023, 04:20:16 pm
content: CaptDon raises a good point. Look on the WWW and there are articles on testing IGBTs. It may be necessary to make up a test rig. Why do you think the ones you bought are fake? Did they come from Aliexpress or ebay? Did they come from a vendor more likely to sell genuine out of production parts?Is this your welding machine or are you repairing it for someone else? If it's a repair for a customer, it may be best to say fixing it is beyond you.I'd be concerned that all 12 IGBTs had failed, which suggests a fault which caused them to fail together. Another set could go the same way, for the same reason, even if they were guaranteed genuine replacements. What sort of use was the machine given when the fault occurred? Was it being lightly used or at full power? Had it been misbehaving before it definitely failed?Do you have the full service manual for the welding machine? Very often they are not released by the maker, and when they are they often suggest board level replacement, not component replacement.Whether the 187W parts are a sensible replacement for the 250W parts depends on factors not easy to know, such as how much margin was built into the design as regards heatsinking.