Nikon charger MH-24 transformer replacement  - Page 1
Forum section: electronics / repair

author: sdancer75
author_rank: Frequent Contributor
timestamp: June 29, 2022, 02:15:49 pm
content: HiIs there any replacement part for the transformer (mark code OR20A153) shown at the attached pictures?The part is from a Nikon charger MH-24. Anyway, how can I possibly know if the two parts are matched? ie, the same primary and secondary resistance?PS : After a fall, the lead conductor is torn apart from it's pin base. I tried to find the edge to reconnect it but I couldn't despite my efforts with my microscope. Anyway, I am thinking to replace it but I don't know the type.Can someone help with this?

author: Uunoctium
author_rank: Frequent Contributor
timestamp: June 29, 2022, 03:53:40 pm
content: looks very close to Eaton ECMT-R Common Mode ChokesExample from Mouser:https://www.mouser.de/ProductDetail/Bussmann-Eaton/ECMT1V2429S-5R0-R?qs=TCDPyi3sCW1elWL00jyiFA%3D%3D

author: Zoli
author_rank: Frequent Contributor
timestamp: June 30, 2022, 05:19:10 am
content: Quote from: sdancer75 on June 29, 2022, 02:15:49 pmLooks like is the 15mH one(153 printed on the top).

author: mariush
author_rank: Super Contributor
timestamp: June 30, 2022, 06:09:54 am
content: If it's a common mode choke, you could just replace it with two jumper wires. The part is there to filter/reduce the "noise" sent back into the AC grid. Without it, maybe an AM radio would not work as well, or something like that, but otherwise it would be perfectly safe.If you look at the traces on the circuit board it would be something like this---- ac ~ ---- ~ + ------ +----- + + ----- +------ +bridge rectifier cap (c1) choke cap (c2) DC-DC converter chip (U2)---- ac ~ ---- ~ - ------ - ---- - - ------ - ------ -Between the two + of the choke you'd have a coil , and between the two minuses of the choke you'd have a coil ... so you could replace with two wires , one between the two + of the choke, one between the two - of the choke

author: sdancer75
author_rank: Frequent Contributor
timestamp: June 30, 2022, 07:25:25 am
content: Yes, my mistake, it is an inductor. I measured about 10mH. The rated current of the inductor should be output current of the charger?Thanks

author: sdancer75
author_rank: Frequent Contributor
timestamp: June 30, 2022, 07:26:18 am
content: Quote from: Uunoctium on June 29, 2022, 03:53:40 pmyes that's true, my mistake.

author: sdancer75
author_rank: Frequent Contributor
timestamp: June 30, 2022, 07:29:59 am
content: Quote from: mariush on June 30, 2022, 06:09:54 amYes, I found out that it is indeed an EMI filter choke. I will try to replace it with a 10mH/1.2A choke but if I don't find one I will short the pins.Thanks,

author: abdulbadii
author_rank: Frequent Contributor
timestamp: June 30, 2022, 09:33:53 am
content: Not transformer, it's common or differential choke, Imo need a schematic

author: tunk
author_rank: Super Contributor
timestamp: June 30, 2022, 10:13:17 am
content: Quote from: sdancer75 on June 30, 2022, 07:25:25 amNo expert, but this is on the high voltage side, so I don't think it needs to.Again no expert, maybe something like this (0.7=70% efficency):8.4V/230V * 1.2A / 0.7 = 0.063A