Transformer ID? - Page 1
Forum section: electronics / projects

author: jinuq
author_rank: Contributor
timestamp: October 28, 2010, 08:50:53 pm
content: Can any one help me ID this transformer or am I miss labeling it a transformer? I have googled for the logo, tha part number, etc. All to no avail.

author: TheWelly888
author_rank: Frequent Contributor
timestamp: October 29, 2010, 10:12:53 am
content: It looks like a switch mode PSU transformer which was specifically designed and manufactured for the PSU it is in. Because of that it is very unlikely you will be able to get a replacement for this transformer even if you contact the PSU's manufacturer.

author: jinuq
author_rank: Contributor
timestamp: October 29, 2010, 05:00:47 pm
content: That was the presumption I was working under. I was still hoping to find the manufacture, if still in business, and ask any ways.

author: Zero999
author_rank: Super Contributor
timestamp: October 29, 2010, 05:22:36 pm
content: It's unlikely it's the transformer which is broken.There's more chance the rectifier, driver transistors or control IC are bad.

author: jinuq
author_rank: Contributor
timestamp: October 29, 2010, 05:36:57 pm
content: Here are pictures of the PCB front and back.Power comes in at bottom left, hits the bridge rectifier gets converted to dc @ 330V. Power is present up to the right side of the transformer everything on the left has no power. I think I am just missing a trace or component that brings power to the other section.

author: jinuq
author_rank: Contributor
timestamp: October 29, 2010, 05:40:42 pm
content: And the back.

author: Zero999
author_rank: Super Contributor
timestamp: October 29, 2010, 05:52:49 pm
content: The PCB traces look fine to me.It's an SMPS, the rectified 330V is chopped up using some switching transistors, passed through the transformer, which reduces the voltage and is rectified to DC with a couple of diodes. The transformer is very robust, more so than a conventional transformer, the semiconductors are the weakest points. My guess is either HS? (on the right hand side of the board), D11, D12 or U4 have failed. Check the diodes first which are the easiest things to test, then check the driver transistors which are probably MOSFETs but you'll need to Google the datasheets to be sure.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 29, 2010, 06:33:39 pm
content: Hero. can you give the reason why do you suspect HS, D11, D12, and esp U4. i have bunch of damaged circuit here that i have no clue to repair (including the PSU that looks like this one), your reasoning might give me some clue. and how do we check transistor or mosfet? do we have to take out off the board? or inboard testing.. how?

author: jinuq
author_rank: Contributor
timestamp: October 29, 2010, 06:59:01 pm
content: @Hero999,Just to make sure my brain is on this morning. When you say HS your talking High Speed?

author: Unknown
author_rank: Unknown
timestamp: October 29, 2010, 07:09:53 pm
content: Quote from: jinuq on October 29, 2010, 06:59:01 pmI assume he means the isolated component on the very right of the second picture, mounted on the heat sink, near the silk screen starting with 'HS' (which is probably for the heat sink itself).

author: jinuq
author_rank: Contributor
timestamp: October 29, 2010, 07:17:00 pm
content: I see this now. Didn't even see that on the pcb. 8^(

author: Zero999
author_rank: Super Contributor
timestamp: October 29, 2010, 08:11:16 pm
content: Look at the right hand side of the board at the components covered in heatshrink and attached to the heat sink. I don't know why the PCB manufacturer used HS rather than standard designators such as Q or Tr for the MOSFET. It's evening in my time zone and I'm pretty alert.Looking at the board again, there's a burn mark next to the resistor on the bottom right of the PCB so I'd check it reads the correct value. The main filter capacitors could also be failing (high ESR).I suggested the semiconductors could be bad because they're the weakest points of the circuit but other components could also have failed and might even be the cause. For example, bad filter capacitors can cause the SMPS to become unstable making the switching transistors work harder and fail.

author: jinuq
author_rank: Contributor
timestamp: October 29, 2010, 08:24:15 pm
content: D11 and D12 are Schottky Rectifiers(S60SC4M) by Shindengen, who stopped making them. They both appear shorted. I was able to find the whole power supply for sale for US $70. So I will probably just chuck it in the bin and get a new one.@Hero999,Thanks for the help. Would you by chance have a list of these standard designators?

author: Zero999
author_rank: Super Contributor
timestamp: October 29, 2010, 08:37:34 pm
content: Did you test the diodes with one of the pins disconnected?You shouldn't need exact replacements, any Schottky diodes with the same or higher ratings should do.https://www.eevblog.com/forum/index.php?topic=972.0https://www.eevblog.com/forum/index.php?topic=1211.0

author: jinuq
author_rank: Contributor
timestamp: October 29, 2010, 09:01:00 pm
content: No, i didn't. I am unfortunately not allocated a lot of time for projects like this.

author: Murphy
author_rank: Regular Contributor
timestamp: November 06, 2010, 05:17:21 am
content: Note that there are actually 2 power supplies on that board. The small one to the bottom left powers the larger one that controls the output. First check if that power supply is functioning it should be putting out some small voltage and if it isn't doing that then the rest of the circuit won't start up. It's possible there is nothing at all wrong with the power electronics.If that smaller output voltage doesn't exist you might have a really cheap/easy fix in that smaller circuit.Check if any mosfets are shorted gate-drain.

author: jinuq
author_rank: Contributor
timestamp: November 06, 2010, 05:25:34 am
content: @Murphy,Thanks for the information. I cheated and just bought a new power supply.

author: Murphy
author_rank: Regular Contributor
timestamp: November 06, 2010, 05:49:25 am
content: Where's the fun in that? =D

author: jinuq
author_rank: Contributor
timestamp: November 13, 2010, 06:09:46 pm
content: There is none. 8^( But work demands my time for other things. No time for exploring.