AL2416W no picture no power indicator

[dwalker615]

can someone please help me trouble shoot this monitor, i have searched the forums and do not appear to be having the two seconds to black problem, as i have no power indicator that appears at all. none of the caps on the power board appear to be bulging. any help would be appreciated! thanks!

[jetadm123]

Re: AL2416W no picture no power indicator

1) If you connect your monitor to the computer and shine a flashlight against the screen, do you see any image?

2) when you press the power button do you see any quick flash of the backlights?

3) if no to above, try measuring the voltage (be careful, it's high voltage!) across the 100uf 450V cap. If you're in the USA, you should read about 165VDC.

4) if you get the 165VDC, then try reading the voltages at the two wiring harnesses.

[dwalker615]

Re: AL2416W no picture no power indicator

no images with a flashlight. power button does nothing. when i unplug it, and plug it back in some times i get a real brief back light flash. 165v on the cap, where do i ground to read the harness?

[dwalker615]

Re: AL2416W no picture no power indicator

left to right, per the picture, voltages are as follows
5.08
0
0
0
.04 but it counts down to about .012
"
0
0
0
0
0
0

next harness
all between 0 and .001

[PlainBill]

Re: AL2416W no picture no power indicator

left to right, per the picture, voltages are as follows
5.08
0
0
0
.04 but it counts down to about .012
"
0
0
0
0
0
0

next harness
all between 0 and .001

Try hitting the power button again and repeat the measurements. This is a dual (Standby and Main) power supply. You have the standby supply, but the main was not operating when you took those readings.

PlainBill

[dwalker615]

Re: AL2416W no picture no power indicator

measurements 2.0 same order
5
0
0
0
4.91
4.90
4.89
0
0
0
0
2.58

next:
0
2.58
0
0
0
0
0
0
0.028
.027
.026
.024
.023

[dwalker615]

Re: AL2416W no picture no power indicator

i just unplugged it, plugged it back in. and took another reading. the last wire in the harness previously .023 was reading approx 23v but was QUICKLY dropping back down to the .023 range again

[jetadm123]

Re: AL2416W no picture no power indicator

Try hitting the power button again and repeat the measurements. This is a dual (Standby and Main) power supply. You have the standby supply, but the main was not operating when you took those readings.

PlainBill

Good catch PlainBill.

Dwalker- Looks like you're getting the 5V on the harness, but not the 24V. Please supply a good closeup photo of the bottom of your power board. Also, what are the part numbers of the two heatsinked devices (circled in red) in the photo?

[jetadm123]

Re: AL2416W no picture no power indicator

Good catch PlainBill.

Dwalker- Looks like you're getting the 5V on the harness, but not the 24V. Please supply a good closeup photo of the bottom of your power board. Also, what are the part numbers of the two heatsinked devices (circled in red) in the photo?

I forgot to mention that I suspect the diode pack on the right supplies the 24V, but we'll need the part number to verify that.

[dwalker615]

Re: AL2416W no picture no power indicator

Good catch PlainBill.

Dwalker- Looks like you're getting the 5V on the harness, but not the 24V. Please supply a good closeup photo of the bottom of your power board. Also, what are the part numbers of the two heatsinked devices (circled in red) in the photo?

on the left per the picture part number stps2045ct on the left and mbr20150ct on the right

[jetadm123]

Re: AL2416W no picture no power indicator

on the left per the picture part number stps2045ct on the left and mbr20150ct on the right

Looks like the mbr20150ct puts out the 24V. The middle leg of the diode is the output. Try performing the same test as post #6, except this time, just measure for the 24V at the middle leg.

[dwalker615]

Re: AL2416W no picture no power indicator

1.54v

[jetadm123]

Re: AL2416W no picture no power indicator

I also should asked you to perform the same test on the stps2045ct to make sure you're still seeing the 5V. If you see the 5V, go to the next step.

To check the mbr20150ct for shorts, turn off and unplug your monitor. With your meter set to ohms, place the black probe on the middle leg and red on the left leg. Record reading. Next, the black probe on the middle leg and red on the right leg. Record reading.

[dwalker615]

Re: AL2416W no picture no power indicator

I also should asked you to perform the same test on the stps2045ct to make sure you're still seeing the 5V. If you see the 5V, go to the next step.

To check the mbr20150ct for shorts, turn off and unplug your monitor. With your meter set to ohms, place the black probe on the middle leg and red on the left leg. Record reading. Next, the black probe on the middle leg and red on the right leg. Record reading.

-.024 Mohm on the right and left

[jetadm123]

Re: AL2416W no picture no power indicator

-.024 Mohm on the right and left

Since you're getting 24K ohms each way, there looks to be no short. The 5V and 24V are each connected directly to different secondaries of the yellow transformer. Looks like there's nothing supplying the input to the mbr20150ct.

1) the secondary winding have opened or shorted for the 24 supply.

2) legs 1 and 3 of the mbr20150ct are connected together with leg 2 providing the output. There might be resistors/capacitors connected across the 1,3 and 2 legs. Check these devices for shorts.

[dwalker615]

Re: AL2416W no picture no power indicator

Since you're getting 24K ohms each way, there looks to be no short. The 5V and 24V are each connected directly to different secondaries of the yellow transformer. Looks like there's nothing supplying the input to the mbr20150ct.

1) the secondary winding have opened or shorted for the 24 supply.

2) legs 1 and 3 of the mbr20150ct are connected together with leg 2 providing the output. There might be resistors/capacitors connected across the 1,3 and 2 legs. Check these devices for shorts.

legs one and three are connected directly to the transformer, they are both coming from the same source on the transformer. there doesn't appear to be anything else bridge across. how do i test the transformer?

[Rtech]

Re: AL2416W no picture no power indicator

I would also look at the components after the mbr20150ct,as I had a similar problem a while ago on another monitor, and the problem was a short ctt after the Schottky pulling the voltage down.If possible isolate the centre leg cct after the filter cap,then measure the voltage

[jetadm123]

Re: AL2416W no picture no power indicator

I would also look at the components after the mbr20150ct,as I had a similar problem a while ago on another monitor, and the problem was a short ctt after the Schottky pulling the voltage down.If possible isolate the centre leg cct after the filter cap,then measure the voltage

I would have thought that a short dragging the voltage that low would have blown a fuse on either the power board or inverter. I suppose one could disconnect the wiring harness to the inverter and check again for the 24V.

Another possibility might be one of the filter caps at the output of the mbr20150ct could be shorted to ground.

[Rtech]

Re: AL2416W no picture no power indicator

Its most unusual for the tfmr to fail, although I have no cct diagram, if he is getting the 5v, then I would assume the tfmr is probably ok, which is why I suggested the secondary after the schottky, and on the flty one I had, no fuses were blown at all,the fault was among the smd components,well away from the schottky.

[bullmuscle]

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