Identify this chip please - Page 1
Forum section: electronics / repair

author: deephaven
author_rank: Frequent Contributor
timestamp: September 10, 2014, 09:20:31 am
content: I have a non-working switch mode power supply which I'm trying to fix. It has an SOT23-6 chip on it marked with 62813 but after Googling, I can't find anything resembling a switch mode controller. It appears to be driving the gate of the main switching mosfet so I'm surprised I can't find anything. Does anyone know what this might be?The power supply is type number HKP10 5v 2.5A made by Hung Kay. It's out of a Roberts Radio MP Sound 53.

author: tautech
author_rank: Super Contributor
timestamp: September 10, 2014, 10:42:02 am
content: Without a clear hi-res photo we do not know the exact layout of those numbers.This can have a major affect as to if a search returns any or no results.But a Google of: "62 SOT23-6 ic data"or"628 SOT23-6 ic data" brings up some results.Normally to get results for coded IC's, you should include the package type and pin numbers in the search.Also coded type IC's in small packages can have only 2 or 3 alpha-numeric characters.You may also have to check a datasheet pinout against the physical circuit and or a "Typical Application" (like shown in many datasheets) to ensure you have the correct one.The last check for confirmation of correct identification is the identifying code as listed in the (hopefully matching) datasheet.

author: Rasz
author_rank: Super Contributor
timestamp: September 10, 2014, 10:50:09 am
content: +1hires pictures of both pcb sides + picture of supply case

author: deephaven
author_rank: Frequent Contributor
timestamp: September 10, 2014, 11:47:00 am
content: I don't have the ability to take a close up picture of the chip. The numbers are in one row with no other markings except a dot marking pin 1.

author: wraper
author_rank: Unknown
timestamp: September 10, 2014, 05:23:13 pm
content: It may be some SG6858, LD7550 clone or similar IChttp://www.fairchildsemi.com/datasheets/SG/SG6858.pdfhttp://www.100y.com.tw/pdf_file/LD7550B.pdfCheck if pinout corresponds to this IC, if yes, then you could try it. But first try to replace electrolytic capacitor and diode connected to the VCC pin. It won't start if capacitor is dead or diode is leaky.

author: wraper
author_rank: Unknown
timestamp: September 10, 2014, 05:32:39 pm
content: And check if resistor or 2-3 resistors in series from HV to VCC pin is ok.

author: deephaven
author_rank: Frequent Contributor
timestamp: September 10, 2014, 05:33:31 pm
content: Quote from: wraper on September 10, 2014, 05:23:13 pmWow thanks! I can't check this till tomorrow but that sure looks plausible.How did you come up with that, is it a standard generic chip used in lots of places?

author: deephaven
author_rank: Frequent Contributor
timestamp: September 10, 2014, 05:34:50 pm
content: Quote from: wraper on September 10, 2014, 05:32:39 pmThanks again, I really appreciate your hints.

author: wraper
author_rank: Unknown
timestamp: September 10, 2014, 07:52:36 pm
content: Quote from: deephaven on September 10, 2014, 05:33:31 pmThere is a shitload of such ICs with identical pinout and almost the same specifications. They are used very widely. They are interchangeable in most cases. One more clone:http://file.yizimg.com/332467/2010080308450435.pdf

author: wraper
author_rank: Unknown
timestamp: September 10, 2014, 09:29:25 pm
content: Figured out what exactly it is. OB2262http://www.hardwaresecrets.com/datasheets/ob2262.pdfMarking is 62YWW, where Y year code and WW week code.http://www.ebay.com/itm/10pcs-SMD-OB2262-2262-Power-Management-Chip-IC-SOT-23-6L-/181275113842?pt=LH_DefaultDomain_0&hash=item2a34d6b972Can be replaced with OB2263, LD7535, LD7550, LD7552, SG6858, SG6859.......

author: deephaven
author_rank: Frequent Contributor
timestamp: September 10, 2014, 09:39:02 pm
content: Quote from: wraper on September 10, 2014, 09:29:25 pmThat's a great piece of detective work, many thanks for all your efforts. I will take a look tomorrow and see if I can figure out what is wrong. I'll let you know how I get on.

author: tautech
author_rank: Super Contributor
timestamp: September 10, 2014, 09:56:54 pm
content: Quote from: wraper on September 10, 2014, 09:29:25 pmseemed logical the 13 at least, was part of the date code.Surprising the there was a 5 digit code on a SOT23?But for all those watching some of the identification coding is a date code, remember that.OP, sometimes there is a very small change in the number spacing or a slightly different font that separates the ID from the date code and that's why we requested an image.So may it have been displayed as 62 813 ?

author: wraper
author_rank: Unknown
timestamp: September 10, 2014, 10:15:04 pm
content: Quote from: tautech on September 10, 2014, 09:56:54 pmOn ebay picture they are just in one row, no different spacing.

author: deephaven
author_rank: Frequent Contributor
timestamp: September 11, 2014, 09:24:57 am
content: What a difference having a schematic makes! I checked around the start-up circuitry where the Vdd is initially supplied by a high value resistor from the rectified mains. There was a very low voltage on this pin and after checking the resistor, electrolytic and the diode (which provides the Vdd when the supply has started up), I concluded that it must be the chip. I took the chip off the board and indeed, the Vdd pad now shot up to a high value (the electrolytic was removed while I did this).I found the Fairchild equivalent at RS Components at £0.37 so will order one and hopefully that will be it.