Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

[HexInverter]

Howdy folks I've lurked these forums a bit but have not registered until now. I was hoping that someone with a whole lot more experience than me could help shed some light on this strange inverter boards problem (I say strange, because I can't find mention of other monitors that use this board)

I got this monitor for free, so I'd really like to get it going and save it from the dump

The unit powers on and displays a nice picture for 5 or 10 seconds and then the backlight turns off. Checking with a flashlight, I can see the picture when the lights are off.

I'm really new at repairing LCD's... I have a decent understanding of basic electronics, but am a mega noob when it comes to repair. So far, I have replaced all of the cheap capacitors that were on there (including the large filter capacitor), and that did nothing. I've checked the fuse, rectifier, as well as any large resistors. All check out fine using the appropriate multimeter tests.

I've scoured high and low on the bottom of the board looking for any indication of a surface mount fuse...I can't find any "F's" or SMD packages that look like fuses (just the standard resistors, caps, transistors, etc). There is however a dual package fet that has some discolouration around it - I found a datasheet for it, but instead of being a normal FET, it's a P and N type in one package - how do I test this guy? (I've never really tested any FETs before...)

Here's the FET's datasheet:
https://cdn.badcaps-static.com/pdfs/...3d6e9db571.pdf

I guess the ultimate thing would be if someone here is familiar with this board and has some specific things I should look at. I did find a service manual for this model of monitor, however the inverter board is not the same

I've attached some pictures for reference (scroll down)!

Thanks for any help!

Pictures:

[jetadm123]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Welcome to the forum! Looks like you did some recaping. Panasonic FC series? It also looks like you forgot to replace the small cap next to the yellow transformer. It's part of the startup circuit. You'll be interested to know that someone else is having similar problems to yours except that the exact same board is in a Westinghouse L2210NW. Unfortunately, there's two different boards in the thread. Your board starts with the member testas86. Take a look at the link below:

https://www.badcaps.net/forum/showthread.php?t=9149

[HexInverter]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Welcome to the forum! Looks like you did some recaping. Panasonic FC series? It also looks like you forgot to replace the small cap next to the yellow transformer. It's part of the startup circuit. You'll be interested to know that someone else is having similar problems to yours except that the exact same board is in a Westinghouse L2210NW. Unfortunately, there's two different boards in the thread. Your board starts with the member testas86. Take a look at the link below:

https://www.badcaps.net/forum/showthread.php?t=9149

Oh hey, sweet - thanks!

And, yeah, I didn't replace that one CapXon - it's a 50v, 22uF cap, and when I was ordering I was ordering for two LCD's I ordered 16v 22uF caps since my other LCD's board had those! haha. Silly me!

I figured that it probably isn't that one and I was overzealous replacing them all to begin with - but maybe I will scrounge my scrap piles and see if there's one I could solder in and test. That would be dreamy if it was that this whole time

I will head over to that thread there and check it out Thanks!

[PlainBill]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

And as a side note, Darfon inverters are notorious for bad transformers. That inverter has two secondaries - one at each end of the transformer. Measure the resistance between the pins at each end. Yeah, I know, they have glue on them.

PlainBill

[retiredcaps]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

And as a side note, Darfon inverters are notorious for bad transformers. That inverter has two secondaries - one at each end of the transformer. Measure the resistance between the pins at each end. Yeah, I know, they have glue on them.

PlainBill

Thread

https://www.badcaps.net/forum/showth...?t=9149&page=3

post #41 through #72 are relevant to transformer testing. You should get 880 ohms if the boards are similar. Look at the other thread posting for the numbering of the pins and you can test the same 1-2, 7-8 pins.

[HexInverter]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Great, thanks for the responses guys

You're so helpful! hehe.

My 1-2 and 7-8 readings are 839/840 ohms, respectively - so I guess that means it's okay? My readings between 3-4 and 5-6 are both .5 ohms.

I looked high and low for a 22uF 50v cap to pop in and try out...

I have come to the conclusion that the one pictured that is currently ON the inverter board is the only one in my whole house! ARGGH! I have BOXES of scrap electronics to pick through - nothing! What luck! I even ripped apart some stuff to see if there was one in there that I could "borrow" for a bit haha. I would have settled for something bigger too but I can't find anything but 16v's!

Shoot...well I guess I'm going to have to make a parts order! Grrr...I just made a whole ton of orders for my other projects and could have got some with that!!! One of these days, I am dropping a couple hundred dollars on capacitors so I never have to not have one again! muahahahaaaa

Anything else I can try in the mean time?

PS: Forgive my tired weirdness. I often get strange when I've spent all day talking to no one but electronic parts

[retiredcaps]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

My 1-2 and 7-8 readings are 839/840 ohms, respectively - so I guess that means it's okay? My readings between 3-4 and 5-6 are both .5 ohms.

Yes, those readings look good.

[retiredcaps]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

I found a datasheet for it, but instead of being a normal FET, it's a P and N type in one package - how do I test this guy? (I've never really tested any FETs before...)

Funny, I just wrote this

https://www.badcaps.net/forum/showpo...3&postcount=11

[retiredcaps]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

The unit powers on and displays a nice picture for 5 or 10 seconds and then the backlight turns off. Checking with a flashlight, I can see the picture when the lights are off.

Interesting that it lasts 5 to 10 seconds. Most of the common complaint is "2 seconds to black".

Try this. Power on the monitor, decrease the brightness and contrast as fast as you can down to 20 and 10 respectively. Most monitors are set to "torch" mode with 90 brightness and 30 contrast or some setting like that. I have most of my monitors at 50/30.

With the new lowered settings, see if the monitor stays on longer.

[HexInverter]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Interesting that it lasts 5 to 10 seconds. Most of the common complaint is "2 seconds to black".

Try this. Power on the monitor, decrease the brightness and contrast as fast as you can down to 20 and 10 respectively. Most monitors are set to "torch" mode with 90 brightness and 30 contrast or some setting like that. I have most of my monitors at 50/30.

With the new lowered settings, see if the monitor stays on longer.

You know...I probably shouldn't have said 5-10 seconds It's been about a month since I had it on to see (when replacing the caps), and I'm also working on another monitor at the same time. I kinda just pulled a number out of my head to be honest - it is more like 2 seconds. I remember trying the lowering contrast/brightness trick for about 10 minutes straight trying to do the menu options as quickly as possible to no avail!

I'm really tempted to try two 10uF caps in parallel...think it's worth a shot? :P

I don't want to wait a couple weeks for new caps to get here

[retiredcaps]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

I kinda just pulled a number out of my head to be honest - it is more like 2 seconds. I remember trying the lowering contrast/brightness trick for about 10 minutes straight trying to do the menu options as quickly as possible to no avail!

If it is 2 seconds, then no, don't worry about the brightness/contrast setting.

I'm really tempted to try two 10uF caps in parallel...think it's worth a shot? :P

Usually, AFAIK, those small 22uF 50V caps are part of the run/startup phase. So if you had symptoms like no power LED on, then I would suggest changing it.

I'm leaning towards potentially bad CCFL or something related to that (bad wiring, bad solder joint). If you have a spare similar sized monitor, try #5 at

https://www.badcaps.net/forum/showthread.php?t=10419

You may want to try it during daytime when you are less tired.

edit: I'm assuming c205 is the 22uF 50V cap? If yes, that is part of the run/startup phase I was talking about.

[jetadm123]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Great, thanks for the responses guys

You're so helpful! hehe.

My 1-2 and 7-8 readings are 839/840 ohms, respectively - so I guess that means it's okay? My readings between 3-4 and 5-6 are both .5 ohms.

I looked high and low for a 22uF 50v cap to pop in and try out...

I have come to the conclusion that the one pictured that is currently ON the inverter board is the only one in my whole house! ARGGH! I have BOXES of scrap electronics to pick through - nothing! What luck! I even ripped apart some stuff to see if there was one in there that I could "borrow" for a bit haha. I would have settled for something bigger too but I can't find anything but 16v's!

Shoot...well I guess I'm going to have to make a parts order! Grrr...I just made a whole ton of orders for my other projects and could have got some with that!!! One of these days, I am dropping a couple hundred dollars on capacitors so I never have to not have one again! muahahahaaaa

Anything else I can try in the mean time?

PS: Forgive my tired weirdness. I often get strange when I've spent all day talking to no one but electronic parts

I once remember reading that the 22uf 50v caps were used because they were the most readily availiable. I know this will be difficult, but if you read the voltage across the cap, you'll find the voltage will be low enough where you might be able to use a cap rated at a lower voltage, say 35V? Also, the idea of using two 10uf caps in parallel is also acceptable.

Have you had a chance to test the dual FET? Your results?

Fuse F301. You checked it, right?

Sounds like th 5V rail is working, since you're getting a picture. The inverter section generally requires 12V or more to operate. Can you go ahead and measure and report these two voltages.

[jetadm123]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Also, what is the part number of the CCFL 16 pin controller SMD chip located on the lower right of the board (same side as the dual FET))?

[HexInverter]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

I once remember reading that the 22uf 50v caps were used because they were the most readily availiable. I know this will be difficult, but if you read the voltage across the cap, you'll find the voltage will be low enough where you might be able to use a cap rated at a lower voltage, say 35V? Also, the idea of using two 10uf caps in parallel is also acceptable.

Have you had a chance to test the dual FET? Your results?

Fuse F301. You checked it, right?

Sounds like th 5V rail is working, since you're getting a picture. The inverter section generally requires 12V or more to operate. Can you go ahead and measure and report these two voltages.

Mmkay, the 16 pin controller IC is BIT3715 - I've unfortunately checked F301 a bunch of times just to be sure and keep getting very low ohm readings, so I'm pretty sure it's good. Checking the dual SMD FET as per Retiredcaps' instructions on the other guys thread showed it was working okay however. I got consistent over range indication so there were no shorts.

As for swapping out CCFL's, I have another Samsung 18.5" here...maybe I could try the CCFL's from that. I'm sort of wary of 600-1000v though, so I'm going to save it as a last ditch measure once I've tried everything on the board here.

Well, I've never tested equipment while it was plugged in before...I'm certainly a careful lad when it comes to electricity, but how do you guys go about setting up a rig for testing inverters? Can you just power the inverter/display board on its own without the LCD plugged in? I can't see a way of probing around safely with all of the cables plugged in when it's all connected to the screen/backlights. Maybe someone could shed some light on that for me.

Also, can you point me in the direction of where to test for 12v? I reckon it's close to the connector that goes to the display board at CN301, but that's about as far as my power supply knowledge goes

And that would be an AC 12v signal I'm looking for, right? I will probe that cap at the same time - I'm just not 100% on where to look for the 12v, and don't want to blow myself or the board up!

Thanks for all the help! It is very much appreciated.

[retiredcaps]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

As for swapping out CCFL's, I have another Samsung 18.5" here...maybe I could try the CCFL's from that. I'm sort of wary of 600-1000v though, so I'm going to save it as a last ditch measure once I've tried everything on the board here.

Here are instructions written from a different point of view.

Take a known good working LCD. Assume it has 4 CCFL connections. Number them 1, 2, 3, 4.

Take cover off known good working LCD and lay it face down on soft surface. You should be able to access the CCFL connectors.

Remove CCFL connector #1 from the good LCD monitor.
Plug in cable for potentially bad CCFL #1 into connector #1 for test.
Plug LCD into power bar and turn on power bar. Now power on LCD. See if 2 seconds to black occurs.
Turn off power bar, unplug LCD power cord. Wait 1 minute.

Repeat same instructions as above for each potentially bad CCFL.

If these instructions don't make sense, don't try it.

Also, can you point me in the direction of where to test for 12v? I reckon it's close to the connector that goes to the display board at CN301, but that's about as far as my power supply knowledge goes

And that would be an AC 12v signal I'm looking for, right?

You are looking for 12V DC (not AC). Yes, it would be one of the connectors to the logic card. Some boards have them marked others don't. To measure for 12V DC, put your ohm meter on 20V DC if it is a manual range one. Put your black probe in COM and red probe in Volts.

Make sure all the screws are put back in. Put your black tip on a ground screw close to the connector. Put your red probe on the 12V pin. It should be marked on the board.

[HexInverter]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Here are instructions written from a different point of view.

Take a known good working LCD. Assume it has 4 CCFL connections. Number them 1, 2, 3, 4.

Take cover off known good working LCD and lay it face down on soft surface. You should be able to access the CCFL connectors.

Remove CCFL connector #1 from the good LCD monitor.
Plug in cable for potentially bad CCFL #1 into connector #1 for test.
Plug LCD into power bar and turn on power bar. Now power on LCD. See if 2 seconds to black occurs.
Turn off power bar, unplug LCD power cord. Wait 1 minute.

Repeat same instructions as above for each potentially bad CCFL.

If these instructions don't make sense, don't try it.



You are looking for 12V DC (not AC). Yes, it would be one of the connectors to the logic card. Some boards have them marked others don't. To measure for 12V DC, put your ohm meter on 20V DC if it is a manual range one. Put your black probe in COM and red probe in Volts.

Make sure all the screws are put back in. Put your black tip on a ground screw close to the connector. Put your red probe on the 12V pin. It should be marked on the board.

Okay, so I am testing my Acer's potentially bad CCFL's with a good inverter board then? Just to clarify - I assumed at first I would be testing my inverter with good CCFL bulbs.

It doesn't sound too hard I always discharge filter caps with a 60w bulb just to be safe.

Okay, so there is a pinout for my header pin connector that goes to the logic board, but it has no 12v on it! I see 3x "5v1" pins, 3x GND pins, one DIM pin, and one ENA pin...nothin' else! Could it be somewhere else?

[jetadm123]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Also, can you point me in the direction of where to test for 12v? I reckon it's close to the connector that goes to the display board at CN301, but that's about as far as my power supply knowledge goes

And that would be an AC 12v signal I'm looking for, right? I will probe that cap at the same time - I'm just not 100% on where to look for the 12v, and don't want to blow myself or the board up!

Thanks for all the help! It is very much appreciated.

Okay, this is how it generally works:

On the heatsink with the two dual diode packs D301 and D302: they each take an output from the yellow transformer and each pack supplies the 5VDC and the other 12VDC (or more).

To measure voltages, make sure everything is put back together. You should be able to measure the 5V at the power supply connector (on the right side) where it's stamped 5V.

The 12V might be a little more difficult, since I didn't see anything marked 12V or more on the connector: You will probably read OV because the system shuts down after 2 sec. However, proper troubleshooting dictates you at least try to read the voltage. I suspect the lone cap (rated 25V?) by itself below the barcode label might be the filter cap for the 12V. Try measuring across that cap. The alternative is to measure the output of the diode pack (D301?) at the common cathode.

The voltage is all DC until it reaches the dual FET, which converts it to the AC voltage required by the inverter transformer.

As for testing the CCFL, try doing a search in this forum using the term:
"ccfl tester", ccfl "testing".

[retiredcaps]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Okay, so I am testing my Acer's potentially bad CCFL's with a good inverter board then? Just to clarify - I assumed at first I would be testing my inverter with good CCFL bulbs.

There are 2 ways of looking at this.

1) I have a good spare CCFL and a LCD monitor with potentially bad CCFLs. This is the scenario described in #5 in the troubleshooting guide.

2) I have a good LCD with good known working CCFLs. Externally I have one or more bad CCFLs from a "bad" LCD. This is the scenario I just wrote in an earlier post.

Both try to achieve the same result -> figure out which CCFLs are bad. Which one you should use just depends on what "spare" equipment you have.

Does that make sense?

[HexInverter]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

There are 2 ways of looking at this.

1) I have a good spare CCFL and a LCD monitor with potentially bad CCFLs. This is the scenario described in #5 in the troubleshooting guide.

2) I have a good LCD with good known working CCFLs. Externally I have one or more bad CCFLs from a "bad" LCD. This is the scenario I just wrote in an earlier post.

Both try to achieve the same result -> figure out which CCFLs are bad. Which one you should use just depends on what "spare" equipment you have.

Does that make sense?

Yup! I just wasn't sure if it was safe to do it both ways or not. I will give that a shot and let you know how it goes.

[retiredcaps]

Re: Acer x193w with Darfon B092-XXX inverter - assistance needed! [lotsa pics!]

Yup! I just wasn't sure if it was safe to do it both ways or not. I will give that a shot and let you know how it goes.

Just take your time and be careful not to short something out by rushing through things. I always use the power bar with nothing else on it and plugged into an single outlet.