// #eevblog — 2019-07-28
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02:42:43 Join: HexicPyth ([email protected]) to #EEVblog
03:48:55 Join: HelloGuize ([email protected]) to #EEVblog
03:49:05 <HelloGuize> Hello Guize!
03:49:41 Quit: HelloGuize ([email protected]) Quit: http://www.kiwiirc.com/ - A hand crafted IRC client
03:52:53 <rust_collector> HELLO!!!
04:10:10 <T3sl4> yo
04:10:35 <rust_collector> yo yo yo...yo
04:11:18 <rust_collector> time for some nice hot coffee
05:05:47 <DHess_US> https://i.ibb.co/YbkjCbq/Are-Flying-Builds-OP-mp4-snapshot-00-18-2019-07-27-14-02-28.jpg
05:36:28 Join: Wisefire ([email protected]) to #EEVblog
05:37:20 <Wisefire> any smart switched PSU aficionados online right now?
05:41:23 <T3sl4> dunno
05:42:04 <T3sl4> whats your problem Wisefire
05:45:18 <Wisefire> trying to repair a roland xp-30 keyboard. PSU is damaged, MOSFET k3115 was in two pieces. don't have a direct replacement with same stats for it, but a friend of mine brought a STGF30V60DF IGBT, and i was wondering how much chance i'd have with replacing the mosfet for that igbt.
05:47:18 <Wisefire> PSU is switched afaik, but i'm slightly out of my league when it comes to knowledge about components, or how switched PSUs are designed.
05:49:05 Quit: rust_collector ([email protected]) Quit: Lost terminal
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05:55:03 <Wisefire> the most obvious remark is obviously "just replace it with the correct part" which i totally get. i might just be a tad impatient.
05:56:30 <DHess_US> If an IGBJ works to replace a MOSFET in a switching power supply, then the design was flawed to start with.
05:56:49 <DHess_US> I would not expect an IGBT to work as a replacement for a MOSFET in that application.
05:58:03 Join: AndrevS ([email protected]) to #EEVblog
05:58:05 <DHess_US> Higher forward voltage drop and slower switching speed will lead to much higher losses. In many cases, the switching speed will be too slow to function.
06:00:21 <Wisefire> what are the specs to watch out for when selecting a replacement mosfet? because the only k3115s i can find are either ebay or Aliexpress, and I am quite wary to buy components from there.
06:00:41 <DHess_US> MOSFETs are all pretty much fast enough so speed is not a problem.
06:00:52 <DHess_US> The voltage and current ratings are important.
06:01:53 <DHess_US> Depending on the controller, you might have to make sure to use a low threshold level device. The controller might not apply enough voltage to turn the MOSFET on.
06:02:20 <rust_collector> internet says the NTE2974 is an alternative
06:02:30 <DHess_US> Power and Rds(on) tend to track current within the same package style.
06:03:44 <Wisefire> @rust_collector i found that one as well, but ordering it might prove troublesome.
06:03:58 <DHess_US> Yea, nothing special about the k3115. Note that k3115 is shorthand for 2SK3115
06:04:25 <DHess_US> TO-220FP package, 600 volts, 6 amps.
06:04:45 <Wisefire> ah, right. good to know.
06:04:56 <DHess_US> http://radiokomponent.com.ua/pdf/tranzistor/polevik/2SK3115.pdf
06:05:43 <Wisefire> a quick side question, why have the designers chosen for a 600v component for 250V application? transients?
06:06:01 <DHess_US> However it is very likely that the gate driver or controller is damaged also. Failure of the MOSFET usually means applying 340 volts to the gate driver circuits which do not like that.
06:06:37 <DHess_US> The input is rectified to 340 volts DC. 400 volts isn't large enough and the next higher common voltage is 600 volts.
06:06:53 <DHess_US> But even so, that is still less than 50% derating.
06:07:33 <Wisefire> right, i forgot about the boost in voltage when you rectify.
06:11:11 <DHess_US> https://www.mouser.com/Semiconductors/Discrete-Semiconductors/Transistors/MOSFET/_/N-ax1sfZ1yzvvqx?P=1yztic7Z1z0y0wnZ1yvncfpZ1z0xzzgZ1z0xn56Z1yuk7vzZ1z0z63xZ1yzxnagZ1z0y3zrZ1yw78f8Z1yw76d3Z1yw76fmZ1yw78ikZ1yw78goZ1yw76ghZ1yw76gdZ1yw76gpZ1yw76ejZ1yw76epZ1yw8ox4Z1yw8nd1Z1yw8okpZ1yw8p7oZ1yw8qfnZ1yw8pkpZ1yw8puqZ1yw8pktZ1yw8purZ1yw8poj&Ns=Pd%20-%20Power%20Dissipation|1
06:11:59 <Wisefire> what actually happened (to paint the full picture) i tried to power the keyboard, no reaction. opened it up. measured a blown fuse (replaced it with a wingnut temporarily) tried powering it on again. house fuse blew immediately. opened it up again. noticed the blown MOSFET. and a lot of broken traces (presumably because the keyboard has had a diffi
06:11:59 <Wisefire> cult life, being dropped a lot (evident because of several broken/missing keys) and i've noticed that one of the transformers(if i identified it correctly) was quite hot. rest of the components seem fine, but damage isnt always evident..
06:12:39 <DHess_US> There is llikely other damage which caused the MOSFET to short blowing the fuse.
06:12:50 <DHess_US> The fuse was not there to protect the power supply. It was there to prevent a fire.
06:13:27 <DHess_US> I'm not saying it will be impossible to fix for someone skilled in the art however fixing it will require more than replacing the power MOSFET.
06:14:31 <Wisefire> this might sound like a weird flex. but soldering stuff isn't an issue. knowing what to replace, however, might be.
06:14:38 <rust_collector> does it need any "special" voltages, or could you ploink a different supply in there?
06:14:59 <Wisefire> afaik it needs +15 -15 and +5 V.
06:15:58 <Wisefire> might some pics help, i've got the PSU out atm.
06:23:51 <Wisefire> took a sec, but here you can see what i'm dealing with:https://imgur.com/a/8Z8sH7Y
06:25:43 <Wisefire> also, i had a look, it was a choke that was getting hot. not the transformer itself.
06:26:54 <rust_collector> I like how that 110 amp wingnut fits in there
06:28:11 <Wisefire> like it was made for it ;)
06:39:34 <Wisefire> obviously not the best decision though, and definitely not a permanent solution.
07:05:58 <rust_collector> with a blob of glue, it should be fine
07:07:22 <Wisefire> hahahah, most definitely!
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07:25:16 <rust_collector> hmm, hello
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07:26:36 <rust_collector> bye
07:29:36 Join: Wisefire ([email protected]) to #EEVblog
07:30:52 <rust_collector> mijn kont jeukt
07:31:29 <Wisefire> hahaha, lekker dan.
07:31:49 <rust_collector> the only dutch I can remember, for some reason
07:32:33 <Wisefire> interesting sentence to remember, tbh.
07:32:56 <rust_collector> i wonder where I got it from. But it is something
07:33:13 <Wisefire> bit weird to drop into casual conversation. or you might get offers to help you with it.
07:34:13 <rust_collector> yeah, it can be risky, I guess. I had many strange offers in various truck stops down there
07:38:34 <Wisefire> well, it's interesting enough that you've been to truck stops where dutch people are.
07:39:11 <rust_collector> I don't think many of them were dutch, but
07:40:08 <rust_collector> holland-land is the place to go, if you want to see dutch truck stops
07:40:43 <rust_collector> I only went there a few times.
07:41:45 <Wisefire> it probably is, though i do not frequent truck stops that often.
07:41:56 <Wisefire> but if you decide to go to holland. don't go to amsterdam.
07:42:46 <rust_collector> For some reason, most of the times I was down there, I went to... uhm
07:42:52 <rust_collector> eeh
07:43:00 <rust_collector> brunssum, I think it was
07:44:38 <AndrevS> Brunssum? Why there?!?!
07:44:59 <rust_collector> that is where the boss told me to go, lol
07:45:09 <AndrevS> lol
07:45:46 <rust_collector> He had a deal with nato-blahblah, to do moving and storage for their employees
07:48:59 <rust_collector> same as when I went to the beautiful city of Lublin, Poland.
07:49:10 <rust_collector> it was because I was told to go there
07:49:28 <Wisefire> brunssum thats about as far away from amsterdam as you can get.
07:50:18 <rust_collector> well, not too far away. i mean, the first time I was going there, I missed all of holland. had to turn and go back and look for it
07:50:37 <AndrevS> Brunssum ain't exactly a tourist destination. Friend of mine used to live there.
07:51:00 <rust_collector> I still think it is incredible that they have stuffed so many people in that little spot
07:51:32 <rust_collector> No, I did not get a very touristy vibe there, but I think it was a nice enough place to be for a few days
07:52:23 <Wisefire> cant imagine it being touristy. most tourists never leave amsterdam.
07:52:38 <rust_collector> well, that is good.
07:53:00 <AndrevS> I suppose Maastricht gets enough tourists.
07:53:12 <AndrevS> Anyways, I'm getting tired, off to bed. bye bye
07:53:17 <rust_collector> good night
07:53:24 <AndrevS> g'night
07:53:28 Quit: AndrevS ([email protected]) Connection closed
07:54:41 <Wisefire> yeah, i'm gonna wrack my brain over how switched psus work some more
07:54:53 <rust_collector> they have (had)a female postie in brunssum, that had the most agressive sound. I was barely awake, and this woman was "yelling" at me
07:55:27 <rust_collector> turns out she was asking if the people living there were moving.
07:55:34 <rust_collector> which they were.
07:56:26 <rust_collector> That was not a good morning. 2-3 hours of sleep, and it was very hot
07:56:30 <Wisefire> , hahaha dutch can sound like yelling sometimes.
07:56:44 <rust_collector> then this agressive crazy lady yelling at me
07:56:53 <Wisefire> anywho. have a good one.
07:57:07 <rust_collector> have fun
07:57:08 <Wisefire> fijne avond!
07:57:18 <rust_collector> same to you
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10:03:22 <DHess_US> Fucking no-see-em. I saw it get into the house when I came in but I had to wait for it to land for a fill up before I could smack it.
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15:18:39 * Halcyon licks damian
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15:50:15 <damian> ooo hi
15:50:17 <damian> i like licks
16:03:40 <Halcyon> Just not from men :P
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