Replace N-Channel MOSFETs - Page 1
Forum section: electronics / repair

author: k.valentino
author_rank: Contributor
timestamp: November 04, 2018, 06:36:47 pm
content: Hi,need alternative to replace 3x N-Channel MOSFETs SUM110N10-09 –https://www.vishay.com/docs/70677/sum110n1.pdfIs it ok to replace with STB120NF10T4? –http://www.farnell.com/datasheets/1817542.pdf

author: boB
author_rank: Frequent Contributor
timestamp: November 04, 2018, 06:41:08 pm
content: Specs are very similar. Very close.I would think it would be fine to replace with for most applications.Why does it need replacing ?

author: k.valentino
author_rank: Contributor
timestamp: November 04, 2018, 08:12:14 pm
content: Quote from: boB on November 04, 2018, 06:41:08 pmI see the difference in the power dissipation. Maximum Power Dissipation (T=25°C) is 375W vs 312W .But I don't know if it will importance.I have faulty brake resistor controller with 3 blown transistors - the photo

author: coromonadalix
author_rank: Super Contributor
timestamp: November 05, 2018, 01:38:19 am
content: Is this a drill brake controller ? wow its was a big pooofThe important stuff in the mosfets are the rds values, internal "resistance drain source" in ohms value and sometimes the capacitance, the dissipated values are near match, i think it would fit.The problem is the tab is completly soldered, you will have to solder it pretty fast with a stong iron, use solder wick to remove completly the solder, tack the 3 pins on the pcb, preventing it from moving, and apply gentle pressure to be sure the mosfet has no clearance under it ans solder it fast as i said. Use flux to help ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 05, 2018, 02:42:09 am
content: Soldering is no problem, just melt and bend the leads up, then dump heat into the tab until it lifts off. Tin and wick the pads clean, then solder down the replacement.I'd be more worried that:1. You haven't addressed the root cause, so it's likely to blow again,2. That looks like it used to be a potted module. In other words, "you poor SOB..."...Fixing a potted module, while absolutely possible, is on the "heroic" side of repairs. Are you sure you can't actually find/buy a replacement, considering all the time and materials you'll spend on this repair? Almost always, such repairs are "penny wise and pound foolish".And when you're done, you have to pot it back up, which means expensive silicone (by the looks of it) resin, and maybe a vacuum chamber to be sure. Otherwise it's just going to fail again, some time later, and much worse, due to whatever environmental contamination they were potting the thing against in the first place.Tim

author: k.valentino
author_rank: Contributor
timestamp: November 05, 2018, 09:39:38 am
content: I think will not have any problem with soldering the transistors.It is worth repairing the module because buying another one costs about 100€Thanks for help me!

author: wraper
author_rank: Unknown
timestamp: November 05, 2018, 09:44:20 am
content: Quote from: k.valentino on November 04, 2018, 08:12:14 pmConsidering they are not even on a heatsink this figure does not matter.

author: coromonadalix
author_rank: Super Contributor
timestamp: November 05, 2018, 11:20:03 am
content: The pcb copper layer is the heatsink

author: wraper
author_rank: Unknown
timestamp: November 05, 2018, 11:34:48 am
content: Quote from: coromonadalix on November 05, 2018, 11:20:03 amAnd how much can it dissipate? A few W?Quote

author: boB
author_rank: Frequent Contributor
timestamp: November 05, 2018, 05:18:40 pm
content: Also, don't forget to at least measure the gate resistor to make sure it is still a resistor. It should be a fairly low value, probably under 100 Ohms or so.Replace it too if needed and if you can find it under that potting material !

author: k.valentino
author_rank: Contributor
timestamp: November 05, 2018, 09:26:48 pm
content: Quote from: boB on November 05, 2018, 05:18:40 pmthe resistors are fine - they are 10 Ohms