AOC 2770VH1 No power

[birdboy385]

I recently acquired this monitor of craigslist and was told it won't turn on. Sure enough I get it home, plug it in and nothing. No response from the power button, no signs of life whatsoever. I decided first obvious thing to do is tear the little bugger apart and look for obvious signs of damage from the power and main video boards. I see nothing out of the ordinary so this is where I am. I took a couple pictures of the power board, I also don't see anything on the board that would give a voltage pinout.

[CapLeaker]

Re: AOC 2770VH1 No power

See if you find any STBY voltage on the connector in pic #2. Check for voltage on the main filter capacitor.
Pic #1 is too blurry... maybe redo that again, straight shot, high resolution.

[birdboy385]

Re: AOC 2770VH1 No power

As mentioned, I don't see a pin layout to see which pin goes to what voltage. I will try to get a better picture. My only camera is my Galaxy S4. I must've jolted a bit when i took the picture. also what would the main filter cap be?. Thanks for the response.

[budm]

Re: AOC 2770VH1 No power

Check that rectangular black fuse too by that connector that goes to the main board.
https://www.badcaps.net/forum/attach...7&d=1474319488

[CapLeaker]

Re: AOC 2770VH1 No power

The objective right now is to find the problem board. It could be the main board, it could be the PSU. You don't need to really know what pin does what just yet. Just put the black probe of your DMM on any GND on the secondary side and probe the pins. I can read GND on that blurry picture on pic 1 near the plug. Just trace it to the plug if you want. Then you know the GND pins on that plug. The rest, plug it in with the main board attached and start to probe the DC V of the other pins.
We just want to find the STBY voltage for now, which is always on. If you get nothing, unplug the main board and probe the pins again. If you still have no STBY voltage, then there is trouble on the PSU.
The main filter capacitor is the large one laying down with the white goo on the primary side. Be careful with that one, as there can be 400V DC on there.
As budm already mentioned, check all the fuses on the PSU.

[birdboy385]

Re: AOC 2770VH1 No power

Well this is interesting. I tested the 2 fuses on the board and both seemed ok. ( I have a pretty cheap multimeter and just ordered a better one that both is auto ranging and measures capacitance.) But when i was preparing to trace the ground. I found this bad solder joint that appears to have suffered some damage. It seems to be one of the pins on the power connector. (either positive or negative) not sure which is which. I would just reflow the solder joint, but the browning around that point concerns me. Not sure how i didn't notice it before but alas. I think we have found at least part of the problem.

[birdboy385]

Re: AOC 2770VH1 No power

I apologize again for the bad photos. alot of times they seem fine in my phone then when i go to upload they look blurry

[budm]

Re: AOC 2770VH1 No power

https://www.badcaps.net/forum/attach...7&d=1474383094
That is bad solder joint, it was arcing due to the cold joint in the beginning.
You need to resolder all 3 pin of that IEC AC inlet, it is bad design due to lack of proper support of the inlet.
Just clean off the black carbonize with Alcohol first then use flux and solder.

[birdboy385]

Re: AOC 2770VH1 No power

Update: I was in the middle of doing just that haha. I have since reasselbmed the monitor partially to the point I can test to see if I have power coming from the standby light and sure enough. I do. I need to finish reassembling the monitor but I do believe it is fixed.

[birdboy385]

Re: AOC 2770VH1 No power

Confirmed, the monitor is now working perfectly. I appreciate all of the help as always.

[CapLeaker]

Re: AOC 2770VH1 No power

perfect!