AL2416W no picture no power indicator

[jetadm123]

Re: AL2416W no picture no power indicator

Hey guys, today I repaired my inverter board by soldering on the new caps. The monitor worked fine until i placed back the thin metal cover that covers the all the back boards. I must have by mistake hit something because the power supply stopped working. God I'm so pissed with myself for not being more careful. I tested the power supply while have all boards disconnected from still does not work. I checked for prices on power supplies and its $100. Dumb!... i was so close to get this thing back up and running. Any suggestions? Know of anyone that can repair these power supplies.
its a PK101V0110I for a Acer AL2416W

Take some good focused photos of the entire power supply and inverter boards. Do not post photos inline, but use the manage attachments button. There are several different supplies that went into this model and we need to see your boards because someone may see something you missed. I take it you get no power light or any signs of life? You made have shorted something when you put the cover on. How did you test the power supply? Try checking the fuses on the power board.

[bullmuscle]

Re: AL2416W no picture no power indicator

On this power supply i can see no fuses. I cannot see fuses on niether the inverter board or the logic board.

[alexanna]

Re: AL2416W no picture no power indicator

On this power supply i can see no fuses. I cannot see fuses on niether the inverter board or the logic board.

Is there any way you could retake the pictures, there really out of focus.
Try to get a good focused shot straight down of the boards; we really need to be able to read the markings on the boards.
There is a remote possibility there may be some fuses on the back side of the boards.

[jetadm123]

Re: AL2416W no picture no power indicator

Fuses are typically marked FXX (where XX is a number), On the power board there is a glass fuse wrapped in heat shrinkable tubing directly behind the power socket. IIRC, on the inverter, there are up to 4 small white surface mount fuses, marked F1-F4.

[bullmuscle]

Re: AL2416W no picture no power indicator

I located the fuse. I tested it and its bad. I will go to radio shack tomorrow to buy the replacement. You guys RULE!

[putergurl]

Re: AL2416W no picture no power indicator

So I'm wondering what dwalker615 came up with on this power supply? I have the same issue as this post, same symptoms. What I've done so far (yeah, I know I'm Easter egging ):

1. I checked for the 165v on the large cap, it's good; I measured voltages at different points around the secondary and found many indications of 5VDC, but no 24VDC. I've not measured any harness voltages yet.
2. I've checked ESR on all the electrolytic caps, and they are all good; in fact they seem almost too good (very low ESR). I removed two of the secondary caps that had very low ESR and they also had seemingly good DC readings as well. Can these present a short for AC and therefore have an extremely low ESR?
3. I removed the mbr20150ct schottkey and it tested good with a multimeter. All the through-hole resistors in the secondary measure good resistance.

Any tips? I'm not familiar with testing surface mount components yet, but I have a feeling I'm going to become familiar soon. I know it's a long shot, but does anyone have a schematic for this power supply or a place to source one?

[budm]

Re: AL2416W no picture no power indicator

The 5V standby/always on is working, this power supply board has PFC Voltage booster circuits, that large cap voltage should kick up to about 400VDC when power switch is activated by PS_ON signal from the logic board. Do you see that 400VDc when you hit the power switch, if not, that is the reason why you do not have 24Vdc output since the 24VDC power supply gets its power from PFC section to run it.
Good pictures of your board on both side and at the connectors will help a lot to find out which pin is the PS_ON pin.

[putergurl]

Re: AL2416W no picture no power indicator

Thank you for the reply budm, sorry for the delay in response. I am pasting links to the pics because i don't see a "manage attachments" button.

https://www.badcaps.net/forum/pictur...&pictureid=212

https://www.badcaps.net/forum/pictur...&pictureid=211

https://www.badcaps.net/forum/pictur...&pictureid=210

[selldoor]

Re: AL2416W no picture no power indicator

Hi - it would have been better if you stated exactly what your problem is
starting from plug in up to the stable fault stage, stating what the power light does what the panel does and if there are any sounds.
If as the op says you have 2 seconds to black you should read this
https://www.badcaps.net/forum/showthread.php?t=10419 start at post 19

Can you post pictures of the main board:
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed
https://www.badcaps.net/forum/attach...1&d=1290283049

https://www.badcaps.net/forum/attach...7&d=1280167246

[putergurl]

Re: AL2416W no picture no power indicator

I do appreciate selldoor pointing me towards how to get the "manage attachments" button to show up. I've included better resolution pics of the power supply as attachments. Please let me know if they are of sufficient clarity or not.

As per post #26, I have already mentioned that I have the exact same symptoms as the OP by dwalker. I also included what I have done myself in post #26. Is it more appropriate to simply start my own thread with the same symptoms, or stick with this one?

To recap, nothing happens when the power switch is pressed, even multiple times. There is no flash, no power light at all, no two seconds to black. There are no bulged caps on any of the boards.

[jetadm123]

Re: AL2416W no picture no power indicator

Sounds like you're getting a 5V Standby voltage. Suggest you connect the logic/video board back to the power supply and measure the input/output voltages of the voltage regulator(s) on the logic board. Also, a photo of the logic board would be appreciated.

[selldoor]

Re: AL2416W no picture no power indicator

OK -pictures are great-thanks- just need the video board- no need for a new thread - As well as the ohm test for shorts on the mbr20150ct did you also do the voltage tests or 24v.
When doing the test as jetadm123 advises do it with power switch on and off.
Cant quite see it in your picture and probably not relevant but is the resistor near the board label bluish - it may be fusible - can you test it?

[putergurl]

Re: AL2416W no picture no power indicator

On the power supply board:

R16 is the small blue resistor to the left of the part number label, it reads 1472 ohms in either direction.

R68 is a large gray resistor just below the part number label, it reads 0 (zero) ohms in either direction - interesting.

I have not yet measured voltages directly on the diode packs, only because it's difficult to reach - if it's truly necessary I'll solder in a lead so I can, please just say so. I'm really starting to lean toward the logic board at this point, but whatever it takes. I really appreciate what you all are helping me learn here.

On the logic/video board:

Since one of the original caps did appear slightly discolored (and I did not yet have my ESR meter) I simply replaced all the caps. The cap that was discolored was the middle cap in the group of three above U17. Unfortunately I disposed of the old caps before getting my ESR meter. Dumb, I know.

The green marker on the empty capacitor spots was simply to help me keep track of where everything went.

I assumed U17 (upper right in the close-up pic) and U18 (bottom of close-up pic) were voltage regulators, please correct me if that isn't so. Voltages were as follows, they did not change regardless of how many times I pushed the power button:

In VDC to ground, reading from left to right with the metal tab on top and leads on the bottom:

U17: .002 - 2.39 - 5.03

U18: .001 - 1.38 - 2.38

Part number on U17: APL1084 WJB2H
Part number on U18: APL1117 GJADZ18

Thanks again all!

[jetadm123]

Re: AL2416W no picture no power indicator

For U17, the "33" stamped on it indicates it should have a fixed voltage output of 3.3V. It also looks like the output of U17 feeds the input of U18. Since you're seeing only 2.39V from U17, then it looks to be bad and should be replaced.

[selldoor]

Re: AL2416W no picture no power indicator

On the power supply board:

R16 is the small blue resistor to the left of the part number label, it reads 1472 ohms in either direction.

what colour rings does it have?

R68 is a large gray resistor just below the part number label, it reads 0 (zero) ohms in either direction - interesting.

If the bands on this are yellow blue silver gold Then it should be 0.46 ohms
Perhaps lift one leg and test again. Meter on lowest ohms

[putergurl]

Re: AL2416W no picture no power indicator

Thanks for pointing me to the regulators jetadm13, that'll be a sight better than replacing the board. I've ordered both regulators just in case, they should be here in a couple days.

On the power supply board, R16 appears to have the following rings:
brown-green-black-brown-brown.
I say "appears" because it's tough to be sure the green one isn't blue, or if I have them listed from the wrong end.

R68 is easy to read: violet-green-gray-gold.

In looking at my previous pics again, I realized one cannot even see R16, or very much of R68, so I've added these pics. I double-checked measuring with the lowest scale on my DMM and it still measured zero, so I'll lift a side of R68 and remeasure ASAP.

[selldoor]

Re: AL2416W no picture no power indicator

R68 is easy to read: violet-green-gray-gold.

Not that easy then I think it will be violet-green-silver-gold
which will be 0.75ohms.

It was really just this one I was interested in as I think it may be a fuse/resistor,They sometimes have a bluish grey body colour so dont bother with the small blue one.

Oddly enough I was looking at someone elses board and their resistors are different.

[putergurl]

Re: AL2416W no picture no power indicator

I thought the third band was silver too, and I've seen this sort of thing before but didn't understand it; how does silver translate as a multiplier for the two significant digits? It's always been my understanding that gold and silver were for the last tolerance spec band only.

"Navy training, Sir!"

[selldoor]

Re: AL2416W no picture no power indicator

Not a clue - type hobby and resistor into your search engine and have a play on that .Gray in that sequence is not an option.

[putergurl]

Re: AL2416W no picture no power indicator

Ahh, this explains it.