Help Identifying Unknown Components - Page 1
Forum section: electronics / beginners

author: fourierpwn
author_rank: Regular Contributor
timestamp: March 14, 2021, 09:10:01 pm
content: Hi all,I am trying to reverse engineer a portion of a pulsed power supply and I am having trouble finding out what these parts are. It was difficult to read the markings on what I've labelled '2' so I wrote it in the image.What surely is the drain of 2 (thickest trace, North side) goes to/comes from the positive output (+15V) of a DCH010515 DC/DC converter. Pin 6 of '3' goes to the input A and B of a IXDD415 dual MOSFET driver IC (other side of board).Any help in identifying these parts would be highly appreciated!Thank you.

author: archil
author_rank: Contributor
timestamp: March 16, 2021, 08:46:54 am
content: cant find any information. looks like transistors.

author: Gyro
author_rank: Super Contributor
timestamp: March 16, 2021, 10:48:22 am
content: The 'U' part idents normally imply IC not transistor.The 8C part looks like it may be a Renesas HA178L56UA Linear regulator. I'm not sure about the L4 part, it also looks like a regulator.

author: archil
author_rank: Contributor
timestamp: March 16, 2021, 10:58:18 am
content: manufacturer's "tricky" marking?

author: fcb
author_rank: Super Contributor
timestamp: March 16, 2021, 10:59:08 am
content: Quote from: Gyro on March 16, 2021, 10:48:22 amAgree. L4 looks like it could be some sort of LM317adjustable regulator, depending on what is connected to R13.

author: gamalot
author_rank: Super Contributor
timestamp: March 16, 2021, 11:06:21 am
content: Quote from: fcb on March 16, 2021, 10:59:08 amAgree +1, L4 should be LM317MDCY:https://www.ti.com/lit/ds/symlink/lm317m.pdf?ts=1615822435798and 8C should be L78L05ABUTR or L78L05ACUTR:https://www.st.com/resource/en/datasheet/l78l.pdf

author: gamalot
author_rank: Super Contributor
timestamp: March 16, 2021, 11:28:47 am
content: I guess that the component in SO-8 package is HCPL-0723 optocouplers, although the external circuit looks a little weird.https://docs.broadcom.com/doc/AV02-0643EN

author: fcb
author_rank: Super Contributor
timestamp: March 16, 2021, 01:44:44 pm
content: Quote from: gamalot on March 16, 2021, 11:28:47 amDoubt it. Pin #7 on the HCPL-0723 is NC.

author: gamalot
author_rank: Super Contributor
timestamp: March 16, 2021, 02:48:56 pm
content: Quote from: fcb on March 16, 2021, 01:44:44 pmTherefore, it won't be any problem if you connect it to ground.

author: fourierpwn
author_rank: Regular Contributor
timestamp: March 17, 2021, 11:40:33 am
content: Quote from: fcb on March 16, 2021, 10:59:08 amAttached is a photo from a neighbouring section of the board. 3 devices in the same SOT-23 package labelled Q, U and D. From this, I assume that the designer was quite meticulous with their designators.Interesting find with the Renesas device!R13 actually does form a divider network with R14, which is on the other side of the board. R14 goes to the source of some power transistors (ARF463AP1G and ARF463BP1G) in push-pull config. I've attached a photo of the other side of the board. IXDD415SI is the dual FET driver. The silkscreen for R14 is a little scuffed, making it hard to read. It is the resistor closest to the left of the IXDD driver chip, with the via coming from R13 being on the South side of R14.I'm trying to work out if the suspected optocoupler makes sense in this application. Pin 7 is connected to the common of the DCH DC/DC converter. Pin 2, which would be the input of the HCPL-0723. This is connected to the output of some 74 series logic (74HC11). There are some other (glue?) logic devices on the input of the board (note, the board I'm reverse engineering is driven by a mainframe/control box which contains the quiescent and non-quiescent bias conditions as well as the pulse timing signals). As I first mentioned, the output (pin 6) of the suspected optocoupler is connected to input A and B of the FET driver IC. Does this make sense?Most appreciative of the excellent work so far! I am happy to provide further information if needed. Thank you!Edit: Not sure why the second image is rotated, sorry!

author: fcb
author_rank: Super Contributor
timestamp: March 17, 2021, 06:59:40 pm
content: Quote from: gamalot on March 16, 2021, 02:48:56 pmCertainly could/should be an optocoupler, and the package looks lumpen like most opto-couplers. Just I don't think it's the HCPL-0723.As the OP is reverse engineering the unit, then presumably they could post the schematic of what they've found so far. Picture being worth a 1K words and all that.