Acer X241W (Power Board Failure)

[wiskeykiller4u]

Re: Acer X241W (Power Board Failure)

were do i get a another one

[PlainBill]

Re: Acer X241W (Power Board Failure)

Danke schön, Herr PlainBill!

SK

Figùrati

PlainBill

[stevekasian]

Re: Acer X241W (Power Board Failure)

Danke schön, Herr PlainBill!

SK

[PlainBill]

Re: Acer X241W (Power Board Failure)

Thanks azeroid.

Thanks PlainBill... The other fuses are 3A, but i have a feeling I'm not searching them properly on the D-K website. Does it sound plausible they wouldn't carry them at all?

SK

No, it's not plausible. Some items are more difficult to identify on DigiKey's website than others. This is one example. The item you want is DigiKey part number F2315-ND, Littlefuse # 0251003.MXL. There are half a dozen equivalent items they carry.

Here's the process I used. This may not help you, but I DO like to brag.

On the opening page, enter fuse in the 'Parts Search' box and click on 'Go'. This brings up a long list of possible matches. Select 'Fuses (23,743 items)'. Click on 'In stock', then 'Apply filters'. That reduces it to a more manageable 4015 items. Next, select '3A', 'Axial', and 'Through Hole', then click on 'Apply filters'. That reduces the number of hits to 14.

And if you look through the list, only two match the color and shape of the original. Since you don't want to buy 1000, that leaves you with one.

PlainBill

[stevekasian]

Re: Acer X241W (Power Board Failure)

Thanks azeroid.

Thanks PlainBill... The other fuses are 3A, but i have a feeling I'm not searching them properly on the D-K website. Does it sound plausible they wouldn't carry them at all?

SK

[azeroid]

Re: Acer X241W (Power Board Failure)

Pay attention to the lead spacing. It is 3.5mm on the board.

[PlainBill]

Re: Acer X241W (Power Board Failure)

Thank you sir. Found the info and confirmed your memory isn't as bad as you think :-D
(And luckily, I only paid $12.00 for the thing!)

What series pico fuse would you say those are? I've got lots of options on Digi-Key.

Uuugh... actually, I don't have ANY options on Digi-Key... they are saying they don't stock them. I must be looking in the wrong place... do you think?

As for the caps, i have options. Would you be so kind as to review my options in the attachment below and give me your feedback?

Thanks,
SK

I'd use the FR series rather than the FC.

What is the current rating of the other fuses - all three should be identical?

PlainBill

[stevekasian]

Re: Acer X241W (Power Board Failure)

Thank you sir. Found the info and confirmed your memory isn't as bad as you think :-D
(And luckily, I only paid $12.00 for the thing!)

What series pico fuse would you say those are? I've got lots of options on Digi-Key.

Uuugh... actually, I don't have ANY options on Digi-Key... they are saying they don't stock them. I must be looking in the wrong place... do you think?

As for the caps, i have options. Would you be so kind as to review my options in the attachment below and give me your feedback?

Thanks,
SK

[PlainBill]

Re: Acer X241W (Power Board Failure)

Sonofagun! You're not kidding! I don't believe it. Someone snipped off the parts! That sneaky little guy, tryin' to tell me it worked fine and then all of a sudden the screen went out one day. Riiiight.

Ok, so somebody sniped parts from my inverter board. But why? It's not like it would be possible to reuse the parts with no legs left on them. So it kind of somewhat rules out the possibility of them taking parts from a "bad" board (mine) to make a good board out of another... which would tend to increase the chances of this inverter actually working with the right parts. (?)

Hmmmm.. so... To order or not to order the missing parts, that is the question.

First things first: I've seen this happen from time to time. The monitor fails. Some wannabe tech opens the monitor, sees bulging caps and puts in replacements. Still nothing, so he looks at the inverter and is actually bright enough to see more bulging caps and discover a blown fuse. So he cuts out the bad parts, intending to see if he can find replacements. Either he loses them, doesn't know what to ask for, or is just lazy, so he puts the monitor back together in hopes of finding someone gullible enough to buy it. That's where you came in.

If you Google the part number of this inverter you will find one or more threads where the inverter is discussed. If I recall, the caps are 180uF, probably 35 volt (You WILL double check this!! Not only is my memory bad, it's short.) The caps and a fuse will cost about $5.00 delivered from Digikey.

The missing fuse protects the inverter controller and drivers Q4 and Q5. It is very possible that the fuse blew because of high ripple inducing oscillations as the caps went bad. Check the drivers; if none are shorted, this is a no-brainer.

PlainBill

[stevekasian]

Re: Acer X241W (Power Board Failure)

Sonofagun! You're not kidding! I don't believe it. Someone snipped off the parts! That sneaky little guy, tryin' to tell me it worked fine and then all of a sudden the screen went out one day. Riiiight.

Ok, so somebody sniped parts from my inverter board. But why? It's not like it would be possible to reuse the parts with no legs left on them. So it kind of somewhat rules out the possibility of them taking parts from a "bad" board (mine) to make a good board out of another... which would tend to increase the chances of this inverter actually working with the right parts. (?)

Hmmmm.. so... To order or not to order the missing parts, that is the question.

[azeroid]

Re: Acer X241W (Power Board Failure)

I was also wondering what happened to them - working on replacing the caps. I posted the pics with the originals here if it helps
https://www.badcaps.net/forum/showthread.php?t=16284

[PlainBill]

Re: Acer X241W (Power Board Failure)

Well, it would've helped matters if I'd posted picts of the inverter board to begin with ;-) (see attached)

F1 is not in use on this board revision. (I swear I didn't cut it off - really)

(And apparently the explanation for the cute numbering job is that everything in the area of F101 is in the 100s.)



Thanks! I'll report back with results...

There IS a reason I ask for pictures.

It appears someone has been working on the inverter with a pair of cutters. In addition to F1, I see three missing electrolytics. If you look at the assembly instructions in the service manual the three fuses and the caps are visible.

PlainBill

[stevekasian]

Re: Acer X241W (Power Board Failure)

No, the first page of the inverter schematic clearly showed a single fuse at the power input. However, when examining the second page of the inverter schematic, they show a second fuse. And when I reexamined the first page, I find a third fuse. Just to be cute, they seem to be numbered F1, F2, and F101. I would expect F1 to be a smaller (physical and current rating) fuse than F101 and F2.

Well, it would've helped matters if I'd posted picts of the inverter board to begin with ;-) (see attached)

F1 is not in use on this board revision. (I swear I didn't cut it off - really)

(And apparently the explanation for the cute numbering job is that everything in the area of F101 is in the 100s.)

IF you locate all three fuses and they are intact, there are a few additional points to measure on the inverter. Transistors Q2, Q1, and Q3 handle level shifting of the On / Off signal. I suggest setting your DMM on the 20 volt range and measuring the voltage on the three pins of those transistors as you press the power button on and off. I would expect voltage changes on all pins of Q1 and Q3, and 2 of the three pins of Q2.

Thanks! I'll report back with results...

[PlainBill]

Re: Acer X241W (Power Board Failure)

> 2. I did not take the readings while a video source was connected. However, i did take the readings as i turned the monitor on and waited for it to go into standby mode. I got the 5V reading every time the display was supposed to be active (not in standby). So I guess that would be equivalent to "every other button press".

Excellent - I was thinking that the readings were taken with the monitor in a standby state. That turns out not to be the case.

> 3. I checked the 2 fuses (yes, there are actually 2) on the inverter and they are not burned.

There is a single fuse on the PS board right at CN2 - perhaps that is what you are seeing on the schematic?

No, the first page of the inverter schematic clearly showed a single fuse at the power input. However, when examining the second page of the inverter schematic, they show a second fuse. And when I reexamined the first page, I find a third fuse. Just to be cute, they seem to be numbered F1, F2, and F101. I would expect F1 to be a smaller (physical and current rating) fuse than F101 and F2.

IF you locate all three fuses and they are intact, there are a few additional points to measure on the inverter. Transistors Q2, Q1, and Q3 handle level shifting of the On / Off signal. I suggest setting your DMM on the 20 volt range and measuring the voltage on the three pins of those transistors as you press the power button on and off. I would expect voltage changes on all pins of Q1 and Q3, and 2 of the three pins of Q2.

I found the service manual the other day, but unfortunately they really dropped the ball on the Power Board section... lol

That is a polite way of describing the utter lack of a schematic for the power supply.

PlainBill

[stevekasian]

Re: Acer X241W (Power Board Failure)

> 2. I did not take the readings while a video source was connected. However, i did take the readings as i turned the monitor on and waited for it to go into standby mode. I got the 5V reading every time the display was supposed to be active (not in standby). So I guess that would be equivalent to "every other button press".

> 3. I checked the 2 fuses (yes, there are actually 2) on the inverter and they are not burned.

There is a single fuse on the PS board right at CN2 - perhaps that is what you are seeing on the schematic?

I found the service manual the other day, but unfortunately they really dropped the ball on the Power Board section... lol

[PlainBill]

Re: Acer X241W (Power Board Failure)

This may have been answered already but are we sure the controll lines for the back light are not on CNS1.I can make out 12V-ground-5V-Ground -On Off -Something? And what looks like ADJ.

They are. If you look at the picture of the back of the power supply two lines run from CNS1 to CNS2. This is a typical arrangement - the two signals originate on the signal card, pass through the power supply and go to the inverter.

The schematics in the Service Manual are pretty cheezy, but the one of the inverter is clear enough. OK, pin 1 is On/Off, and should be at 5V to turn the inverter on. Pin 2 is the brightness.

PlainBill

[alexanna]

Re: Acer X241W (Power Board Failure)

This may have been answered already but are we sure the controll lines for the back light are not on CNS1.I can make out 12V-ground-5V-Ground -On Off -Something? And what looks like ADJ.

[PlainBill]

Re: Acer X241W (Power Board Failure)

Thanks for the info.

So how would you proceed with this at this point if this was your project?

I'd put it on the shelf until I had the urge to work on it. Then I'd play 'Angry Birds' or help someone on the Badcaps forum until the urge went away.

OK, I'll try to offer some real help. First, the service manual is at Elektrotanya. That may help.

1. The manufacturer REALLY isn't helping; the pins on the power supply aren't labeled, which is unusual. I haven't seen pictures of the signal card, but they usually don't label the connector pins. The best hope is the inverter. That MIGHT give a clue.

2. As I mentioned, the two signal (control) lines are at unusual voltages. There are a number of reasons for this. Were the readings taken while the monitor was connected to a working computer? If not, that would explain the strange readings.

3. The fact that the backlights never come on, but the monitor does display a desktop leads me to suspect the inverter, in particular the fuses.

4. A simple test is to monitor the voltages on the two control pins in question while pressing the power button slowly. If the voltages change on every other button press, the problem MUST be in the inverter or possibly the backlights.

5. I took a look at the service manual, and surprisingly they had a schematic of the inverter. Pin 1 is On/Off, 2 is brightness, and there is a single fuse.

PlainBill

[stevekasian]

Re: Acer X241W (Power Board Failure)

Thanks for the info.

So how would you proceed with this at this point if this was your project?

[PlainBill]

Re: Acer X241W (Power Board Failure)

I know it's the connector to the inverter! :-p But everyone always says that the inverter only gets 12V or more. So the control lines are on the 5v lead?

And what is the "signal card"?
SK

1. The inverter POWER is often 12V, 18V, or 24V. The CONTROL signals are usually much lower 0-3.3V for Off/On and 1-3V for brightness.

2. The control lines come from the signal card. Don't confuse the power carried on a connector with the control signals on a connector. At least one manufacturer (Samsung?) feeds 15 volts to the signal card on one model.

3. The signal card is also called the video card, control card, or logic card. I prefer 'signal card' because most people will not confuse it with the video card in the computer, the power supply, or the panel card.

PlainBill