Camera repair - Replacing two inductor in series with one inductor - Page 1
Forum section: electronics / repair

author: Psi
author_rank: Super Contributor
timestamp: June 30, 2013, 07:56:22 am
content: So a mate flew my FPV plane into the metal pole of a soccer goalpost and the camera took such an impact all 3 of the inductor cores inside cracked.Not to worry too much, it was actually his cameraIn any case i was about to put a digikey order in for some other stuff and though i might as well get 3 new inductors to attempt a repair.All 3 of them say 221 on the case and i managed to get the LCR meter on two of them which gave values between 198uH and 213uH @ 100khz so i'm pretty confident of the value is 220uH.The two things im not sure about is-- Core type.I'm 95% sure they're all ferrite but does anyone else notice any signs otherwise..?I know the two that are mounted together are part of the switchmode boost converter that does 5V -> 12V but i'm not sure what the other one does.- Inductors in seriesThere's two 220uH that were mounted at 45 degrees in the air and soldered together in series then covered in red silicon.I would prefer to replace them both with a single inductor because it would mount better. Are there any issues with doing this?- ValueI cant find a 440uH inductor that fits, the closest is 390uH and 470uH. Any idea which would be the better choice?Thanks

author: SeanB
author_rank: Super Contributor
timestamp: June 30, 2013, 10:28:01 am
content: Current rating would be a problem, you probably will need ones with at least a 1A rating or so to work there, just look for ones about the same pin pitch and the same height or a little taller that will fit. The 2 in series would probably be best replaced by the 470nH one, it is a higher value so adding a little more will not be bad. As well check current ratings, in most of these they are 1A rated, choose parts for SMPS use.

author: Psi
author_rank: Super Contributor
timestamp: June 30, 2013, 10:36:18 am
content: The entire camera (RCV922CAM) only draws 200mA @ 5VAll of the suitable digikey replacements (dc/dc application, physical size and inductance) are rated between 0.14A and 0.28Ahttp://www.digikey.co.nz/product-detail/en/SDR0403-221KL/SDR0403-221KLCT-ND/2352924http://www.digikey.co.nz/product-detail/en/SRN4018-221M/SRN4018-221MCT-ND/3821530http://www.digikey.co.nz/product-detail/en/VLCF4028T-471MR14-2/445-6551-1-ND/2465857

author: SeanB
author_rank: Super Contributor
timestamp: June 30, 2013, 10:50:59 am
content: Probably will do then, as they are meant for SMPS use or power supply filtering. Just measure the DC resistance of the remains of the ones you have and order ones that are the same or a lower resistance. Just order 5 of each value, if you have a minimum order or a fixed shipping cost.

author: Psi
author_rank: Super Contributor
timestamp: June 30, 2013, 12:59:14 pm
content: Yeah, one was 3.5R and the other was 6.2R

author: Psi
author_rank: Super Contributor
timestamp: June 30, 2013, 09:58:33 pm
content: na, the two indicators join together together in mid air.A sepic converter would have them separateA lot of video chips run on 12V.I'm not sure if every chip runs on the boosted 12V of if some of it runs on the 5V direct.I'm think it's just china manufactures using two inductors because one was more expensive due to size restriction.I cleaned up the area and the PCB pad is the same as the one on the other side. So the PCB was intended to use a single inductor.