Trying to replace transformers of an inverter board with similar ones - Page 1
Forum section: electronics / beginners

author: Saintron
author_rank: Newbie
timestamp: August 29, 2025, 09:42:52 am
content: I have an old Chimei CMV ct-723d LCD monitor. The monitor was purchased around 2003 and was used for many years before breaking around 2016. In the years leading up to that, the problem manifested as the screen suddenly going black during normal use, and the solution was to unplug the power adapter and plug it back in. (This monitor's power supply is an independent 19VDC adapter.) I had no understanding of circuits at the time, so I couldn't check this problem and just continued using it. During the last time I used it, when I turned on the monitor, I heard a continuous buzzing sound like that from a transformer coming from the monitor itself(not the adapter). After using it a while, the monitor started flickering, and finally went completely black with a large exploding sound, then with a burnt smell. Normally, when the power is plugged in, the panel indicator light at the bottom of the monitor shows orange, meaning it's in standby mode, and pressing the switch turns it blue. This time, even the orange indicator light didn't appear when the power was plugged in. I tested the power supply interface and it could output 19V normally, but there was no response when plugged into the monitor. Since I couldn't repair it, I put it in storage for many years. Just now I took it out again. Out of curiosity, I plugged the power back in to check, and it worked normally again - it could display the orange standby indicator light, and pressing the switch would turn it on normally.I just find an article which describing the symptom exactly the same as mine. See point 4:https://jestineyong.com/test-lcd-inverter-transformer/Now I'm about to replace the transformer. But I cannot find the exact inverter board in my country. I find a similar board though. Are the transformers exchangeable?This is my inverter board PWB-IV90110T.This is the board I can get online PWB-IV125110T.The label on the transformer of my board is "F190 D363" and the other is something else.

author: Buriedcode
author_rank: Super Contributor
timestamp: August 29, 2025, 11:38:26 pm
content: Whilst theremaybe the same model of transformer in similar monitor display boards- there are rarely off-the-shelf parts, and quite often custom for that design. Are you certain that this is the problem? and not with another part?The transformer core and bobbin size can be standard, but the pinouts and perhaps more importantly, the actual inductance/winding ratios of the windings will most likely be custom.With that said, I see a few options.1) Find a replacement board - I know you said you can't find the exact inverter in your country, but sometimes on ebay or even aliexpress these things pop up jsut as the bare board.2) Try to measure the properties off the transformers - this can be extremely difficult. You can't really know the exact windings but you can get a rough idea of the ratios by measuring inductance, and the pinout can be worked out either injecting signals and see the other winding on a scope, or.. tracing out the surrounding components .One thing in your favour here - it look like it uses a dual half bridge (or is it full bridge?) CCFL driver chip:https://www.alldatasheet.com/html-pdf/1170444/ETC1/OZ960G/110/1/OZ960G.htmlThe datasheet should have example schem to see *roughly* whats on the board.In this case, if you can somehow (I know, tall order) find a monitor/display where the supply is the same voltage, and the output tubes are the same size, then theoretically, they should use a similar transformer - at least in terms of electrical properties. Pinout is another matter, because nothing is standard in that area.So, in summery - unlikely to find the exact part based off its model number. And finding one similar enough to work in that circuit is again unlikely, but its an interesting quest..Are you sure its an issue with the transformers? They don't look potted, so secondary arcing can be the issue.I know you've probably checked ebay, but I found :https://www.ebay.co.uk/itm/303638590119https://www.ebay.co.uk/itm/144877418036https://www.ebay.co.uk/itm/293063892154Not sure if any ship to China

author: Saintron
author_rank: Newbie
timestamp: August 30, 2025, 09:13:22 am
content: Thanks for your detailed reply! I'm gonna check the properties of the transformer and the IC later.However, I've just found some more info. The exact inverter board(PWB-IV90110T) is used by Acer AL1714 and there is the service manual online.https://www.manualslib.com/manual/269394/Acer-Al1714.htmlPlease check out the ifixit page here to confirm it.https://www.ifixit.com/Guide/Acer+AL1714+Power+Supply+Board/31047What's more, the PWB-IV125110T board is used by Acer AL1714sm.https://monitor.espec.ws/section33/topic195633.htmlThe Acer AL1714 is a 17 inch LCD manufactured at about the same year as my CMV ct-723d and I found the PWB-IV125110T board uses OZ960G too! See the HD image in this page.https://www.tvpartsguy.com/westinghouse-ltv-17svl-inverter-board-pwb-iv125110t-2714000016/These may increase the possibility of the compatibility between the transformers on these two boards, do they?

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: September 18, 2025, 07:59:32 am
content: These monitors use cold cathode fluorescent lamps (CCFLs) for backlighting. The inverter board (your PWB-IV90110T) boosts the 19 VDC supply up to hundreds of volts AC to drive the CCFLs. Buzzing, flickering, and eventual “pop + smoke” almost always mean either the inverter transformer insulation broke down, or one of the high-voltage caps / MOSFETs failed.When it went completely dead, something shorted hard, blowing a fuse or tripping the primary stage.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 19, 2025, 04:46:20 am
content: Before accusing the transformers of being faulty, I would do a quick and dirty hi-pot test with a megger or similar.