LCD Backlights Driver - Unknown Component - Page 1
Forum section: electronics / repair

author: 2X
author_rank: Frequent Contributor
timestamp: July 18, 2023, 05:28:58 pm
content: Hi,I have an "LCD Backlights Driver" and it is not working. After measurments and checking the routes of the PCB I beleive that this component on the red circle is a choke for filtering the supply voltage and block noise from the inverter to go back to the main board. When I measured in ohm and in diode mode with multemeter shows always OL. Am I right that this is a choke and if yes what value do you beleive is (maybe 15uH or the 15 on the component is just an SMD marking code?)?Chips Datasheets:TL5001https://www.ti.com/lit/ds/symlink/tl5001.pdf?ts=1689617330693&ref_url=https%253A%252F%252Fwww.google.it%252FLA6339https://datasheetspdf.com/pdf-file/390880/Sanyo/LA6339M/1

author: fzabkar
author_rank: Super Contributor
timestamp: July 18, 2023, 06:23:10 pm
content: I agree that the component looks like a 15uH choke. I would be tempted to bypass it with a wire link or a fuse, just for testing purposes.

author: 2X
author_rank: Frequent Contributor
timestamp: July 18, 2023, 06:50:03 pm
content: Quote from: fzabkar on July 18, 2023, 06:23:10 pmWhat "Maximum DC Current" do you suggest to put to the new one.https://gr.mouser.com/c/passive-components/emi-filters-emi-suppression/ferrites/ferrite-beads/

author: fzabkar
author_rank: Super Contributor
timestamp: July 18, 2023, 07:03:39 pm
content: I would take the rating of the backlight as a reference.Pbacklight = Vin x IinIin = Vin / Pbacklight

author: 2X
author_rank: Frequent Contributor
timestamp: July 18, 2023, 07:09:12 pm
content: Quote from: fzabkar on July 18, 2023, 07:03:39 pmIf I measure with a multimeter the current that it draw when it works and then multiply it by 1,5 times?Ichoke = Imultemeter * 1,5

author: fzabkar
author_rank: Super Contributor
timestamp: July 18, 2023, 07:13:19 pm
content: Sounds like a good approach.

author: 2X
author_rank: Frequent Contributor
timestamp: July 21, 2023, 05:08:36 pm
content: In ferrite beads there is no characteristic of inductance. Do you know in which category I have to find it. The current that I measured with multemeter is 550mA, so I want rated current 1,5x550mA=825mA~1Α.https://gr.mouser.com/c/passive-components/emi-filters-emi-suppression/ferrites/ferrite-beads/?q=chokeAll Categories:https://gr.mouser.com/c/?q=choke

author: Jwillis
author_rank: Super Contributor
timestamp: July 22, 2023, 02:28:47 am
content: The SOT-563/EMT6 code D3 is a NPN + PNP digital transistors.https://www.s-manuals.com/smd/d3https://www.s-manuals.com/pdf/datasheet/e/m/emd3%2C_imd3a%2C_umd3n_rohm.pdfNot a regulator.

author: fzabkar
author_rank: Super Contributor
timestamp: July 22, 2023, 03:05:36 am
content: I'm not sure that the RF choke is 15uH. It looks too small. I'm wondering whether it is 15nH.

author: 2X
author_rank: Frequent Contributor
timestamp: July 22, 2023, 12:34:18 pm
content: Finally this is a fuse. This type of fuse consider slow, or Medium, or Fast blow(I beleive)?Fuse Datasheet:https://www.koaglobal.com/-/media/Files/KOA_Global/EN/product/commonpdf/ccp.pdfhttps://gr.mouser.com/c/circuit-protection/fuses/surface-mount-fuses/?current%20rating=1.5%20A&fuse%20size%20%2F%20group=1206%20%283216%20metric%29I found this below. The broken was 1.5A/75V/1sec@250%of Ampere Rating and the replacement I found is 1.5A/125V/5sec@200%of Ampere Rating. Do you beleive the difference in the time will not safe?https://gr.mouser.com/ProductDetail/Littelfuse/047001.5DRSNP?qs=gt1LBUVyoHldARnbZDuW6Q%3D%3Dhttps://www.amazon.co.uk/AGOUNOD-fuse-100pcs-Micro-CCP2E/dp/B0B62FQX1N?th=1https://www.aliexpress.com/i/32770933783.html