Asus VW246H will not power on

[lukjoly]

Re: Asus VW246H will not power on

Hi all,

Similar problem here with my VW246H.
For quite a while it's had problems with turning back on when switched off (either by the power button or the mains).
Dealt with it for a while by just leaving it on standby all the time but finally had to turn the mains off and now can't power up.

When I plug in the AC cable there is a very brief flicker on the power LED but nothing else, did the tests from above and am getting 5v through the same pins as others to the mainboard, both 3.3V and 1.2V regulators test ok.

Any other thoughts? It's a pretty old monitor at this point and probably just going to replace but thinking it might be worth a shot if it's an easy fix.

..is any regulator (3.3V and 1.2V) getting hot ? If not, did you try to give a look to the capacitors ?

[magicsmoke12]

Re: Asus VW246H will not power on

..is any regulator (3.3V and 1.2V) getting hot ? If not, did you try to give a look to the capacitors ?

Regulators not getting hot, didn't see any caps looking damaged.

Had it unplugged and then tried plugging it in one last time and I now have a different problem:
When I turn it on now I get backlight (no image displayed) for about 2 seconds, then off, then another 2 seconds of backlight then it switches to standby.
If I click the input select I get backlight for another couple of seconds then back to standby, even with a computer connected.

I can power off with the power button and when I switch on again the same thing repeats.

Looking less fixable by the day now.

[swofra]

Re: Asus VW246H will not power on

Hey all,
Total noob, trying to figure things out as well. No power, no standby light for me either. Based on board markings, looks like I have a slightly older power board version so I'm posting board pics as I don't know exactly what else is different than OP's pics.

Here is what I have:
- Fuse F501 doesn't register any ohms (OL) with power off, however when plugged in and one lead is placed on the ac terminal and one on the BR ac input I register 122V (I'm from the US). Does this mean power is going through and the fuse is actually ok?

The Bridge rectifier's DC contacts register 10V DC one time and then the next time I plug it in they could be as low as under 2 DC.
I've tested the bridge rectifier in diode mode and it reads ~.5 at all three points, and zero if i reverse the probes.

I get no power at the CN701 connection.

Where do I need to go from here?

Thanks!!

[swofra]

Re: Asus VW246H will not power on

Sorry, fuse I referred to in earlier post is actually F601

[swofra]

Re: Asus VW246H will not power on

Anybody had a chance to review and/or have any insights?

[budm]

Re: Asus VW246H will not power on

Hey all,
Total noob, trying to figure things out as well. No power, no standby light for me either. Based on board markings, looks like I have a slightly older power board version so I'm posting board pics as I don't know exactly what else is different than OP's pics.

Here is what I have:
- Fuse F501 doesn't register any ohms (OL) with power off, however when plugged in and one lead is placed on the ac terminal and one on the BR ac input I register 122V (I'm from the US). Does this mean power is going through and the fuse is actually ok?

The Bridge rectifier's DC contacts register 10V DC one time and then the next time I plug it in they could be as low as under 2 DC.
I’ve tested the bridge rectifier in diode mode and it reads ~.5 at all three points, and zero if i reverse the probes.

I get no power at the CN701 connection.

Where do I need to go from here?

Thanks!!

1) That fuse is blown if your Ohm meter is showing 'OL', it should show the same resistance reading when you touch the two probes of your Ohm meter together.
2) When you measure between the two inner legs of the bridge rectifier should shows 120VAC if the fuse is NOT blown.

[swofra]

Re: Asus VW246H will not power on

Ok, replaced fuse F601 and now have 123VAC at the inner terminals of the Bridge Rectifier (BR) and 159VDC at the outer BR terminals. Big Brown cap also has 159VDC. With the logic board plugged into the main board only (meaning the logic board isn't plugged into the monitor buttons). I tested the green (soldered) side of the board CN 701 connection and didn't get VDC readings on any of the solder points that corresponded to pin position.
First, I just want to make sure that's a valid way to test CN701, and second, if I'm not getting power there, what else could be the problem/test next?

thanks!

[budm]

Re: Asus VW246H will not power on

I just got the PM.
Check the resistance of resistor R615, it should be less than 1 Ohm.

BTW, Can I get good clear hi-res straight shots pictures of the whole top side and bottom side of the power supply board? The one in your post #63 I cannot use it to trace the circuits.

[swofra]

Re: Asus VW246H will not power on

Bud,
Thank you for the reply! The R615 resistance was 0.3 ohms. Attached are pics of the board. Also, just want to make sure that testing the solder points on the green side of the board is effective as testing the top of the board.
Thanks again!

[budm]

Re: Asus VW246H will not power on

Bud,
Thank you for the reply! The R615 resistance was 0.3 ohms. Attached are pics of the board. Also, just want to make sure that testing the solder points on the green side of the board is effective as testing the top of the board.
Thanks again!

OK, thanks for the pictures, I will download them and mark the test points for you to test tomorrow, it is 1AM my Bay Area time right now and very busy with so many people every nights, so good night for now.

[budm]

Re: Asus VW246H will not power on

I am sorry I have been very busy with so many people PM me for helps.
Tuesday tomorrow I am having by dental surgery done so more likely I will be on pain med for a next couple days, I hope you can wait.

[budm]

Re: Asus VW246H will not power on

Notes: do not touch anything on the board with your hands or body, you to need to at least plug the board under test into the GFCI outlet to protect yourself.
OK, just power up the power supply board by itself without any cable connected to the main logic board, then check DCV Voltage on the top side of the board between 'GND' (jumper JW20) and point 'A' (jumper JW17 to see if you have any DCV there or not.

Do you have any 22 ~ 47uF with 25VDC rating or higher? If you do not get any Voltage reading from the test above, you can try replacing C606 start up cap to see if the power supply will start up.

[swofra]

Re: Asus VW246H will not power on

Firstly, hope your dental surgery went splendidly, or as splendidly as something like that could go.
I plugged in the board to a GFCI without it connected to the logic board (logic board cable still attached to power board but its not to logic board - hope that doesn't matter).
Tested the VDC between the output terminals of the bridge rectifier and got 160VDC to verify my meter and power connection was working.
I tested the VDC between GND JW20 and Point A JW17 by putting one probe on each. I tried reversing the probes as well and also tried doing it on the green side by touching a probe to one of the solder points on JW20 and using the other probe to touch one of the solder points on JW17. All tests showed -0 VDC after about 2-3 seconds. i would imagine that would mean there is zero power between the two.

I take it from your suggestion that not getting any VDC somehow means that C606 could be bad and I should replace it? I will look to see if I have any 22 ~47uF 25VDC caps on old boards I've saved, if not, is your recommendation to order one? Looking at that cap, it says 47 uF 50V, do I need to match that exactly?

Thanks again!

[budm]

Re: Asus VW246H will not power on

Firstly, hope your dental surgery went splendidly, or as splendidly as something like that could go.
I plugged in the board to a GFCI without it connected to the logic board (logic board cable still attached to power board but its not to logic board - hope that doesn't matter).
Tested the VDC between the output terminals of the bridge rectifier and got 160VDC to verify my meter and power connection was working.
I tested the VDC between GND JW20 and Point A JW17 by putting one probe on each. I tried reversing the probes as well and also tried doing it on the green side by touching a probe to one of the solder points on JW20 and using the other probe to touch one of the solder points on JW17. All tests showed -0 VDC after about 2-3 seconds. i would imagine that would mean there is zero power between the two.

I take it from your suggestion that not getting any VDC somehow means that C606 could be bad and I should replace it? I will look to see if I have any 22 ~47uF 25VDC caps on old boards I've saved, if not, is your recommendation to order one? Looking at that cap, it says 47 uF 50V, do I need to match that exactly?

Thanks again!

My surgery got cancel due to complication so it will be next Tuesday instead.
Just try the caps that have just for testing just to see if you get any Voltage reading at all when you try the test cap., I f you have two 22 you can connect them in parallel, or parallel 33 and 22, it will be close enough.

[swofra]

Re: Asus VW246H will not power on

Partial success! Thank you so much! I swapped a 47uF 100v into C606 and immediately had roughly 19VDC between JW20 and JW17. How did you figure out the startup Cap was C606 and had something to do with JW20/JW17? I completely hooked up the rest of the monitor and had power on the logic board and the standby board. However, the monitor would only come on with a complete white screen flash twice and then go back to standby. I took VDC readings on the logic board connector receptacle from the power board and to the monitor control panel from the logic board. Not sure how to tell which power terminal does what but they either all read 5-5.4V, 3.3V, some low mv...except one on the logic board terminal heading to the standby board that reads 4.47 VDC

[budm]

Re: Asus VW246H will not power on

Please read post #51 and #53 about Voltage regulator on the logic/main board.
https://www.badcaps.net/forum/attach...6&d=1577135961

[swofra]

Re: Asus VW246H will not power on

I already checked that and its good. Sorry should have mentioned that earlier

[budm]

Re: Asus VW246H will not power on

So the 3.3V on the logic board is steady, correct?
Can I see how all the boards and screen are connected together?

[swofra]

Re: Asus VW246H will not power on

Here are photos as best as I can get. I had to disassemble to get the photos.
To see the other sides of the boards I had to disconnect the pcb/panel ribbon from the screen. The pic with a red circle on identifying the PCB/screen ribbon where it is normally attached when fully assembled. The 4 inverter lights on the right side of the board are also normally plugged in but you can't see those on that view of the boards either. Hope this is close to what you wanted. oh, and don't worry, I have anti static measures and only placed on carpet because it was the best lighting. Thanks again!!

[budm]

Re: Asus VW246H will not power on

"I completely hooked up the rest of the monitor and had power on the logic board and the standby board. However, the monitor would only come on with a complete white screen flash twice and then go back to standby"

Does it stay on if the ribbon cable to the LCD panel not connected and the monitor is also connected to the running PC?

https://www.badcaps.net/forum/attach...9&d=1598068094