Help identifying blown IC - Page 1
Forum section: electronics / repair

author: Kaar3l
author_rank: Newbie
timestamp: September 13, 2024, 04:34:51 pm
content: Hello!I have circuit board from garage door opener motor. That board is providing power when the opener is in standby mode. So the garage door opener works but when it goes to standby after 90 sec it dies. I have identified that one chip is broken and on the chip are markings SC…….. The IC should help to create the standby voltage. I did identify capacitor negative side C4. The output from here should be 12v, on the mainboard is marking 12v at VCC pin.I also did measure voltage on C4 and it was very high about 300v. I will measure later again.It seems that it is some kind DC-DC voltage converter.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 13, 2024, 04:48:22 pm
content: check LNK62XDG LNK304DN-TL .... datasheet ....TNY278GNbut yours seems SC ....Semtec SC2608 SC1104B ....you have to search SO-8C packages

author: fzabkar
author_rank: Super Contributor
timestamp: September 13, 2024, 06:05:27 pm
content: The logo appears to belong to Power Integrations.https://www.power.com/products/ac-dc-conversion

author: Kaar3l
author_rank: Newbie
timestamp: September 13, 2024, 06:54:01 pm
content: Quote from: coromonadalix on September 13, 2024, 04:48:22 pmTNY278GN schematic in datasheet seems very very similar, only some few details seem different.The board has name: et-evopwb-rI'll be looking other datasheets.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 14, 2024, 12:02:17 am
content: Quote from: fzabkar on September 13, 2024, 06:05:27 pmthat would maybe LinkSwitch-TN2Qhttps://www.power.com/sites/default/files/documents/rdr-707q_9pt75w_automotive_non-isolated_buck_linkswitch-tn2q.pdf

author: Kaar3l
author_rank: Newbie
timestamp: September 14, 2024, 05:24:39 am
content: Quote from: coromonadalix on September 14, 2024, 12:02:17 amThe example circuit seems very different from the pcb I have got.I made bigger picture with microscope.

author: Harry_22
author_rank: Frequent Contributor
timestamp: September 14, 2024, 07:24:17 am
content: a little closer...

author: xavier60
author_rank: Super Contributor
timestamp: September 14, 2024, 07:27:28 am
content: There used to be parts beginning with "SC",https://www.lcsc.com/datasheet/lcsc_datasheet_2308151758_POWER-INTEGRATIONS-SC1145DG-TL_C7527508.pdfI can't confirm from the photos that the FB pin is fed from a divider from the transformer winding.

author: Harry_22
author_rank: Frequent Contributor
timestamp: September 14, 2024, 07:45:53 am
content: very close

author: Kaar3l
author_rank: Newbie
timestamp: September 14, 2024, 11:57:31 am
content: I did some pictures with microscope and stiched together.

author: xavier60
author_rank: Super Contributor
timestamp: September 14, 2024, 12:38:02 pm
content: I'm assuming the 2nd pin down on the transformer connects to R8 and R13, so something from the LNK623-626LinkSwitch-CV Family should be suitable.My main experience is having replaced hundreds of blown LNK624DG on washer controller boards for the last 10 years. I soon discovered that using the LNK626DG as a replacement greatly improved reliability.The higher numbered variants have higher peak current so there is some risk of transformer saturation but never occurred in my situation.Also, a small percentage of transformers get damaged by the high current surge during the blow-up. I can pick them by checking primary resistance as it is already known to me.

author: Kaar3l
author_rank: Newbie
timestamp: September 14, 2024, 04:25:21 pm
content: Quote from: xavier60 on September 14, 2024, 12:38:02 pmThanks!I ordered LNK626 and estimated time of arrival is 19.09.2024. When I receive it I will report.

author: Kaar3l
author_rank: Newbie
timestamp: September 19, 2024, 11:51:26 am
content: Quote from: xavier60 on September 14, 2024, 12:38:02 pmThank you!Soldered new chip in place and checked with multimeter and it gave 12v DC.The faulty chip the garage door opener started maybe 1 in 10 times. Now I have tested it and it started 10/10 times so it fixed the opener.

author: LaurenceW
author_rank: Frequent Contributor
timestamp: September 29, 2025, 07:42:32 pm
content: One year on! I've just found this thread and have suffered EXACTLY the same problem, so am pursuing the same fix! Thanks everyone involved.