Common mode choke replacement  - Page 1
Forum section: electronics / repair

author: JustinLoos
author_rank: Contributor
timestamp: December 09, 2023, 06:50:16 pm
content: Hi, I’m looking to replace a common mode choke to a power supply.Power supply (315 watt power rating)Power supply Model # 1920Power Input (alternating current AC)100-127V 4.5A 50/60 HzPower Output (direct current DC)200-240V 2.25A 50/60 HzI hooked up the common mode choke to a tester. 0.3 omhs L (inductance) = 7.33mH (millihenry)I’m struggling to find a replacement. What specs in a common mode choke would suffice a replacement? Current rating (Amps), mH, etc.?

author: BertB
author_rank: Newbie
timestamp: December 29, 2023, 03:37:51 am
content: How do you know the choke has gone bad? 0.3ohm doesn't seem unreasonable (considering it is a thick copper wire). You also mention the power supply model is 1920. Is there any more info on this power supply as to who made it?

author: fzabkar
author_rank: Super Contributor
timestamp: December 29, 2023, 05:35:05 am
content: Quote from: BertB on December 29, 2023, 03:37:51 amhttps://www.eevblog.com/forum/repair/power-supply-repair-(xbox-series-x)/

author: ArdWar
author_rank: Frequent Contributor
timestamp: December 29, 2023, 05:36:56 am
content: Why do you want to replace it in the first place?That being said, if your choke was indeed in microhenry range you probably indeed need to change it into something in the milihenry range...

author: srb1954
author_rank: Super Contributor
timestamp: December 29, 2023, 05:53:29 am
content: Quote from: JustinLoos on December 09, 2023, 06:50:16 pmIs it millihenry or microhenry?The small "m" is the prefix for milli. The correct prefix for micro is a lower case "u" or the Greek letter "µ" (mu).

author: Haenk
author_rank: Super Contributor
timestamp: December 29, 2023, 07:56:01 am
content: Before the choke goes bad, the PSU goes thermonuclear. Do these ever go bad?The measurements look very reasonable, no reason to replace.

author: JustinLoos
author_rank: Contributor
timestamp: December 29, 2023, 01:00:18 pm
content: The above choke is part of an Xbox series x power supply. My xbox stopped working after it accidentally fell. I dissembled it down to the power supply. No voltage coming from the power supply. I could hear some rattling inside the power supply. Upon open the power supply the above choke was broken off the board. I would simply solder them on but the legs are way too short. Too short to even add extension.Thus, I’m stuck looking for a choke replacement.This is what I know about the power supply:Power supply (315 watt power rating)Model #1920Power Input (alternating current AC)100-127V 4.5A 50/60 HzPower Output (direct current DC)200-240V 2.25A 50/60 Hz

author: JustinLoos
author_rank: Contributor
timestamp: December 29, 2023, 01:05:07 pm
content: It’s millihenry (mH) 7.33

author: JustinLoos
author_rank: Contributor
timestamp: December 29, 2023, 01:05:43 pm
content: That’s my mistake. It’s It’s millihenry (mH) 7.33

author: MarkF
author_rank: Super Contributor
timestamp: December 29, 2023, 02:42:11 pm
content: Quote from: Mario87 on December 06, 2023, 10:45:15 amIt's just a choke to reduce noise.Like @Mario87 said, just unwrap one loop from each side to keep it balanced and solder it back in.

author: JustinLoos
author_rank: Contributor
timestamp: December 29, 2023, 02:58:28 pm
content: Tried that, the black adhesive is rock hard. I ended up breaking 2 legs trying to unwrap them. Then I tried breaking up the black adhesive mechanically but not having much luck.

author: BrokenYugo
author_rank: Super Contributor
timestamp: December 29, 2023, 04:11:13 pm
content: I'll hazard a guess you'll be close enough if you try to get the inductance close (give or take a mH), current rating obviously needs to be 4.5A or greater (5 looks common), carefully check dimensions, if the replacement has a base and rigid pins the pin spacing obviously must match the hole pattern and pinout on the PCB.A parametric search on mouser/Digikey will likely give many good options.Edit:forgot about pinout, not sure how standard that is.

author: JustinLoos
author_rank: Contributor
timestamp: December 29, 2023, 04:51:10 pm
content: Thank you!

author: wraper
author_rank: Unknown
timestamp: December 29, 2023, 04:57:30 pm
content: Even if it cannot be fixed by unwinding a turn, you can simply solder some extension wires or rewind it from scratch. Not to say if you just use 2 jumper wires instead of it, PSU would still work just fine.

author: bdunham7
author_rank: Super Contributor
timestamp: December 29, 2023, 05:11:53 pm
content: Quote from: JustinLoos on December 09, 2023, 06:50:16 pm5A and up, 5 to 10mH and the correct physical dimensions including lead spacing. Just use the parametric search on Mouser. This works electrically, but I don't know your physical dimensions:https://www.mouser.com/ProductDetail/KEMET/SCT25XV-050-1R0A027JH?qs=QNEnbhJQKvYT82kOc3gDww%3D%3D

author: JustinLoos
author_rank: Contributor
timestamp: December 29, 2023, 05:45:27 pm
content: Thank you!!! This is very helpful!