Advice on sourcing replacement diode bridge - Page 1
Forum section: electronics / repair

author: JKKDev
author_rank: Regular Contributor
timestamp: November 30, 2020, 11:27:14 am
content: Hey guys,I'm looking for some advice on sourcing an original FUJI part nr.6RI30G-160.I just aquired a VFD/inverter unit by Speecon (7200G3 7.5 kW/10hp). The story is that the factory had a power surge and the inverter stopped working. Every time it was connected afterwards it blew a fuse.Testing for continuity on the inputs reveals shorts between all 3 input phases and the neutral.Diving a bit deeper we arrive to the affore mentioned diode bridge where all 3 phases meet for the first time. The bridge is shorted between all 3 phases and the negative side of the DC side of the brige. Positive to negative side acts as expected for 2 diodes in series.At this point I haven't desoldered the bridge yet as I need to figure out how to do it with the massive posts. After that I should be able to 100% confirm it was the bridge that got blown (I'm almost 100% even at this point).My question at this point is:If it turns out that the brige is at fault should I just get one from China from eBay (basically I'm afraid of getting a subpar part and it blowing up at full power) or is there a better way to source a reliable part?Thank you for any help you can provide and have a nice day

author: wraper
author_rank: Unknown
timestamp: November 30, 2020, 11:53:07 am
content: QuoteNever buy power semiconductors from ebay, aliexpress or Utsource, unless you have no other choice. You may look for it at LCSC though.

author: JKKDev
author_rank: Regular Contributor
timestamp: November 30, 2020, 01:35:44 pm
content: I'm thinking I'd be better off replacing the part with a similar but current product.Sooo... Since in the end, we are only talking about a 3 phase diode rectifier I would think a replacement with similar or higher current capabilities, at least the same or higher reverse voltage, and close to the same forward voltage would be completely reasonable.Are there any other specs I should be aware of when buying a replacement?There's also the problem of properly connecting the module. The current module is soldered to the PCB however most of the ones I can find have a different footprint. This would result in mounting the component to the heatsink and connecting it to the board with wires. I wonder what size wire would be ok for this (input is 3ph 380V-460V and the output is 3ph 0V-460V 13.7kVA 18A).

author: wraper
author_rank: Unknown
timestamp: November 30, 2020, 04:12:34 pm
content: Quote from: JKKDev on November 30, 2020, 01:35:44 pmIn this case IMHO you should go ebay/ali route rater making modifications. I guess this is fairly safe to be genuine and not salvaged from e-wastehttps://www.ebay.co.uk/itm/Three-phase-rectifier-bridge-module-MDS30A-1600V-bridge-rectifier-Square-/233566420524or just search for MDS30 or MDS30A

author: fzabkar
author_rank: Super Contributor
timestamp: November 30, 2020, 07:17:15 pm
content: You can use an NTE equivalent, if you are prepared to pay their ridiculous price.http://www.nteinc.com/specs/5700to5799/pdf/nte5741.pdfhttps://www.digikey.com/en/products/detail/nte-electronics-inc/NTE5741/11647900?s=N4IgTCBcDaIHIBUCiBWA7AFgIwgLoF8ghttp://dilp.netcomponents.com/cgi-bin/nteinc.asp?partnumber1=NTE5741

author: JKKDev
author_rank: Regular Contributor
timestamp: November 30, 2020, 09:00:10 pm
content: If I was repairing it to return to the factory the NTE would be an option. For personal use, however one or two Chinese modules will do the trickat least to test the health of everything else. Thank you guys for the suggestions.