Acer AL2423W: Recapped, Still Dead!

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

Can I check these voltages with just the power supply plugged in? It will be hard trying to do it plugged into the monitor but I can give it a shot if need be.

Pics as requested. Any others, just ask. I broke out the DSLR this time so the pics will be better than the previous ones that sucked.

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

BTW, in the pics, the numbers on the chips are upside down.

[PlainBill]

Re: Acer AL2423W: Recapped, Still Dead!

Can I check these voltages with just the power supply plugged in? It will be hard trying to do it plugged into the monitor but I can give it a shot if need be.

Pics as requested. Any others, just ask. I broke out the DSLR this time so the pics will be better than the previous ones that sucked.

OK, I was correct. Pin 1 is in the upper right corner; pin 2 is the pin to the left of it. given that there are no output voltages from the power supply, just plug in power; it's not necessary to hook up anything else.

What I would like is the voltage on all of the pins of IC1 and IC2. You can use the - lead of the large capacitor as the ground point.

As always, use the proper precautions when working on line voltage equipment.

PlainBill

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

IC1:

1: 145mV *
2: 2.4mV
3: 2.4mV
4: 2.4mV
5: 2.4mV
6: 3.4mV
7: 58mV
8: 80mV, 116mV *

IC2:

1: 116mV *
2: 2.4mV
3: 2.4mV
4: 2.4mV
5: 2.4mV
6: 2.4mV
7: 46mV *
8: 200mV *

* Seems everytime I checked, I would get different values on these pins. Some would steadily decrease or increase.

[PlainBill]

Re: Acer AL2423W: Recapped, Still Dead!

IC1:

1: 145mV *
2: 2.4mV
3: 2.4mV
4: 2.4mV
5: 2.4mV
6: 3.4mV
7: 58mV
8: 80mV, 116mV *

IC2:

1: 116mV *
2: 2.4mV
3: 2.4mV
4: 2.4mV
5: 2.4mV
6: 2.4mV
7: 46mV *
8: 200mV *

* Seems everytime I checked, I would get different values on these pins. Some would steadily decrease or increase.

OK, that indicates the chips aren't getting power. I'd appreciate having a larger picture of the area. Roughly I'm looking for a picture of the board without the shield, and a single shot as large as can be uploaded to this site of the area within the yellow lines.

PlainBill

[Dgtech]

Re: Acer AL2423W: Recapped, Still Dead!

I'm curious, what is the part numbers to Q1, Q2, and Q3? Q1 and Q3 are on the bottom heatsink and Q2 is on the top one. What DC voltages do you get on those pins?

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

Q1: K3569
6-8

Q2: 5D163
K3530
01

Q3: 04N70BF
540191

How exactly do I check the voltages on these? Been a long time since my electronics courses in college.

Bill, your pics are below. Anything else, let me know!

I appreciate everything, fellas.

[PlainBill]

Re: Acer AL2423W: Recapped, Still Dead!

Q1: K3569
6-8

Q2: 5D163
K3530
01

Q3: 04N70BF
540191

How exactly do I check the voltages on these? Been a long time since my electronics courses in college.

Bill, your pics are below. Anything else, let me know!

I appreciate everything, fellas.

Wow!!, this is tough. I've marked up the picture to indicate some points on the bottom that I want identified on the top.

As I indicated, IC2 appears to be the controller for the standby SMPS, while IC1 is for the main SMPS. I've labeled some points of interest. Point 'A' is pin 8 on IC2; point 'B' appears to be the source of the power; it goes through R43 and R44. Check the resistance of both R43 and R44, also what components on the top side of the board are connected to points 'A' and 'B'?

I have even more questions about IC1; I've used up letters 'C' through 'F'. Again, I'd like the components on the top side identified.

One thing, it appears that power for the SMPS controllers is coming from what I identified as a PFC circuit. What is the part number for IC6?

PlainBill

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

Point A is one leg of cap C17.

Point B is one leg of jumper J8 which leads to the pad north of it right under the label "R60". If you draw a line straght up from B, you will hit it. From there it seems to run to a giant trace that includes the choke wrapped in yellow tape.

R43: 5.58k ohms

R44: 5.59k ohms

Point C is one leg of cap C8.

Point D does not go thru the board; it's just a pad.

Point E is one leg of cap C22 (one of the primary side ones I have on order). The other leg is just east of there, under label "R31".

Point F is one leg of jumper J3. The other leg is just north, at the double pad connection. That second pad belongs to diode D4 whose other leg is just west of the double pad.

IC6:

28051
58M
AL7T

Has a logo on it that looks like this: U

Thanks!

[PlainBill]

Re: Acer AL2423W: Recapped, Still Dead!

Point A is one leg of cap C17.

Point B is one leg of jumper J8 which leads to the pad north of it right under the label "R60". If you draw a line straght up from B, you will hit it. From there it seems to run to a giant trace that includes the choke wrapped in yellow tape.

R43: 5.58k ohms

R44: 5.59k ohms

Point C is one leg of cap C8.

Point D does not go thru the board; it's just a pad.

Point E is one leg of cap C22 (one of the primary side ones I have on order). The other leg is just east of there, under label "R31".

Point F is one leg of jumper J3. The other leg is just north, at the double pad connection. That second pad belongs to diode D4 whose other leg is just west of the double pad.

IC6:

28051
58M
AL7T

Has a logo on it that looks like this: U

Thanks!

Once again I've been busy with Paint. It's not as much fun as fingerpainting, but the cleanup is easier.

If I interpreted your description correctly, the dashed yellow line represents jumper J8. Please confirm. Does the trace from the north end of J8 go to point A or B on my latest masterpiece?

What is under the blob of glue I circled in blue?

I'll have to do more research to identify that IC.

PlainBill

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

Once again I've been busy with Paint. It's not as much fun as fingerpainting, but the cleanup is easier.

If I interpreted your description correctly, the dashed yellow line represents jumper J8. Please confirm. Does the trace from the north end of J8 go to point A or B on my latest masterpiece?

What is under the blob of glue I circled in blue?

I'll have to do more research to identify that IC.

PlainBill

Yes, the dashed yellow line is indeed J8. The north trace goes to point A. Point B is only one of the two pads on that trace island.

The glue blob (ground shield offset) has nothing under it. Just the rest of the crosshatch symbol along with an R6 (north) and an R14 (south) label.

You drew a blue line but didn't ask about it. It's diode D14. A big boy.

Thanks, Bill. All this is greatly appreciated.

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

Bill:

The caps just came in the mail. Should I change the rest out now or do we keep poking around at the circuit?

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

Well, I got impatient and changed all the caps.

When I got to the last one (C22, the big 4.7uF 250V one) I realized I ordered a 25v version by mistake. The last 0 was hard to see while it was in-circuit. Blah, that's the bigger one of group which was the most suspect. So I just ordered the correct cap along with some other things I needed from Digikey.

Tried to fire it up and still nothing.

Incidentally, the video board is what "turns on" the monitor. (The power switch connects to the video board) This doesn't affect my testing of the PSU when on the bench, correct? It should still show 5v & 12v at CNS1 on the bench, even with the video board not connected commanding it "on"? I don't need to ground the ON/OFF pin or anything? (Which is what the Video Board does when the power button is pressed, I am assuming)

Just want to make sure I am bench testing this correctly.

Thanks, fellas!

[PlainBill]

Re: Acer AL2423W: Recapped, Still Dead!

Well, I got impatient and changed all the caps.

When I got to the last one (C22, the big 4.7uF 250V one) I realized I ordered a 25v version by mistake. The last 0 was hard to see while it was in-circuit. Blah, that's the bigger one of group which was the most suspect. So I just ordered the correct cap along with some other things I needed from Digikey.

Tried to fire it up and still nothing.

Incidentally, the video board is what "turns on" the monitor. (The power switch connects to the video board) This doesn't affect my testing of the PSU when on the bench, correct? It should still show 5v & 12v at CNS1 on the bench, even with the video board not connected commanding it "on"? I don't need to ground the ON/OFF pin or anything? (Which is what the Video Board does when the power button is pressed, I am assuming)

Just want to make sure I am bench testing this correctly.

Thanks, fellas!

OK, a momentary confusion. Actually, a few points I need clarified.
1. The blob of glue - does it cover a single pad, or a pair of pads? I'm trying to establish how IC2 gets power, and am unable to establish a clear picture.

2. Operating the power supply without load is not a great idea, but it is unlikely that is the cause of the problems. Without a schematic, I can't be sure, but here is how I see this working. AC power comes in and is filtered and rectified. IC2 gets power through R43 and R44. This allows it to start up and produce 5V standby, which powers the 'video card' (what I refer to as the logic card, neither term is as unambiguous and short as I would like). When the logic card gets power it initializes, then monitors the buttons. When it is 'told' to turn on, it turns on the power LED, the LCD panel, and the main supply.

Certainly, if the blob of glue covers a single pad and R43 and R44 are the right value (they are), IC2 should have at least 16 volts on it.

Ah!! Referenced to the - lead of C1, what is the voltage on J8 with the monitor plugged in and the power switch on?

PlainBill

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

The blob covers two separate pads. The cross hatched pad and the pad with your A on it are two separate traces.

Voltage at J8 and C1- is 155VDC. 2VDC Less than at C1- and C1+.

The monitor power switch is a tactile momentary button type. Pressing it does not change the readings.

Can do all this with the ground shield removed or do I have to keep soldering it on and off each time I try to power on? Can I just jumper the three leads together for bench testing?

[PlainBill]

Re: Acer AL2423W: Recapped, Still Dead!

The blob covers two separate pads. The cross hatched pad and the pad with your A on it are two separate traces.

Voltage at J8 and C1- is 155VDC. 2VDC Less than at C1- and C1+.

The monitor power switch is a tactile momentary button type. Pressing it does not change the readings.

Can do all this with the ground shield removed or do I have to keep soldering it on and off each time I try to power on? Can I just jumper the three leads together for bench testing?

You should be able to do this with the shield off. The three points should all go to the chassis ground. G2 and G3 ARE connected to one another. Check continuity to G1.

More points to test in a little while.

PlainBill

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

No cont. to G1 from the other two. That's why I was asking. So far all tests have been done with the shield in place but I dunno how much more bending those leads can take.

[PlainBill]

Re: Acer AL2423W: Recapped, Still Dead!

No cont. to G1 from the other two. That's why I was asking. So far all tests have been done with the shield in place but I dunno how much more bending those leads can take.

Check the shield and make sure all three are connected. If they are, use a jumper wire to tie them together. I'd use a fairly heavy gauge insulated wire and keep it as short as possible.

IC6 is a UCC28501 PFC controller. Check the voltage from pin 8 to pin 6.

PlainBill

[CleanSC]

Re: Acer AL2423W: Recapped, Still Dead!

Voltage between pin 6 and 8 is just a few millivolts. Around 7.

[PlainBill]

Re: Acer AL2423W: Recapped, Still Dead!

Voltage between pin 6 and 8 is just a few millivolts. Around 7.

OK, this is driving me nuts!! I'm having problems tracing this area. Earlier you had given me a nice big picture of IC1 and IC2 and the area surrounding them. Now I need the same for the area around IC6. The same size as the one for IC 1 & 2 would be great, and covering roughly the area outlined in yellow.

FWIW, I'm having trouble figuring where IC6, pin 8 is connected.

PlainBill