Acer AL1916

[Rtech]

Re: Acer AL1916

If we can assume that you are applying a signal from a Computer to the monitor, and the LED power light changes colour to recognise that signal....then you can take out the cable connecting the logic board to the screen and try cleaning the contacts and re-seating,if that does not work then check to see if the fuse on the board with the screen attached,is blown.

[lvikamloops]

Re: Acer AL1916

I had an acer 1916 C come from a friend to see if i could fix it.
Just a white screen. No on screen video, just a blank white screen.
I had replaced the 470mfd16v caps and the 680mfd25v caps on the power supply. Still only get a white screen. Any Ideas on what could be the issue? Is the video controller board suspect?

[Borgleader]

Re: Acer AL1916

If you read the entire thread, the second test suggests shorting the bottom 2 pins with a small screwdriver, while hitting the power button. This sets the reset pin to zero (ground). Some people actually removed U406 altogether (I don't recommend this). Read the entire thread and decide for yourself.

I'm not planning on trying the other test, he said it himself there is a chance it could fry the component (if it isn't already) and it's dangerous.

Connect the positive wire to the top lead of U702 (that's the large 'transistor' just to the left of U406, the reset controller). Connect the negative wire to the bottom lead of U702. Now check the voltage at the upper pin of U406, then the lower right pin of U406. Then disconnect the battery. The upper pin should have been at about 3 volts.

If the voltage on the lower pin of U406 was less than .5 volt, it was holding the reset line low, and the reset controller is working properly. If it was slightly lower that the upper pin, the reset controller is not working properly.

Ok so I retested it, but I wasn't able to get the 3V on the upper pin. On multiple occasions I was able to get 1.5V and once 2.4V, however it seemed like the smallest of movements would change the value I get dramatically. Sometimes I'd shift a few degrees to the left and the value would drop from 1.4V to below 0.3V, and considering the way the components are placed I tried all the angles I could.

In all of the tests however the lower right pin was always at 0.7V which is the value he was expecting, but considering the variation i get in the other one, I'm not sure how much it means at this point.

[jetadm123]

Re: Acer AL1916

Sorry for the delay, just got back to Uni and haven't got used to my schedule yet.

Ok so I Ctrl+F U406, and I took the same measurements that PlainBill asked for in the other thread, and I got the same results, that is:
Left pin: 0.00V
Middle pin: 4.92V
Right pin: 4.30V

And so I proceeded with his test (unlike the other poster I chose the battery version). And I got:
Top pin: 0.4V & 0.01V (We werent able to repeat the 0.04V however, so it could be a fluke)
Right pin: 0.05V

I cant deduce anything from his post however since he assumed that the top pin would have 3V on it, although the fact that it doesnt may mean the part is bad, or maybe the soldering gave out?

If you read the entire thread, the second test suggests shorting the bottom 2 pins with a small screwdriver, while hitting the power button. This sets the reset pin to zero (ground). Some people actually removed U406 altogether (I don't recommend this). Read the entire thread and decide for yourself.

[retiredcaps]

Re: Acer AL1916

And so I proceeded with his test (unlike the other poster I chose the battery version). And I got:
Top pin: 0.4V & 0.01V (We werent able to repeat the 0.04V however, so it could be a fluke)
Right pin: 0.05V

I suggest retesting this again. Please try to use the same terminology as in PlainBill's post so it makes it easier for us to track and read.

If you are not getting 3V on the upper pin, that means something is wrong.

[Borgleader]

Re: Acer AL1916

I just started reading the other thread it looks like 14.5V DC ish is correct. So nix the measurement on the D921.

edit: okay, you may want to read about U406 as per PlainBill's posts.

Sorry for the delay, just got back to Uni and haven't got used to my schedule yet.

Ok so I Ctrl+F U406, and I took the same measurements that PlainBill asked for in the other thread, and I got the same results, that is:
Left pin: 0.00V
Middle pin: 4.92V
Right pin: 4.30V

And so I proceeded with his test (unlike the other poster I chose the battery version). And I got:
Top pin: 0.4V & 0.01V (We werent able to repeat the 0.04V however, so it could be a fluke)
Right pin: 0.05V

I cant deduce anything from his post however since he assumed that the top pin would have 3V on it, although the fact that it doesnt may mean the part is bad, or maybe the soldering gave out?

[retiredcaps]

Re: Acer AL1916

I just started reading the other thread it looks like 14.5V DC ish is correct. So nix the measurement on the D921.

edit: okay, you may want to read about U406 as per PlainBill's posts.

[retiredcaps]

Re: Acer AL1916

As for CN701, pin 5 doesn't have a cable in it so I didn't manage to get a reading, but pin 6 had a reading of ~14.5V DC.

Hmm, that voltage looks a bit high. It should be 12V DC.

F902 is ~0.3 ohms (I used a scale of 200, didn't have 20).

D921 (ohm scale 20k, 2k was not enough):
1) put red on pin 1, black on pin 2: 3.96k
2) put red on pin 3, black on pin 2: 3.92k
3) put red on pin 1, black on pin 3: 0k

D921 (diode test):
1) put red on pin 1, black on pin 2: 0.232
2) put black on pin 1, red on pin 2: 1. (the manual says to reverse the leads if i get this, which ends up being 1) )
3) put red on pin 3, black on pin 2: 0.231
4) put black on pin 3, red on pin 2: 1.

F902 and D921 test good.

Let's try measuring the voltage on D921 pin 2 (middle pin). Put your black probe on the ground screw in the top left. Red on pin 2. Report the DC V measurement.

Hmm, I will have to think about this. You are getting 5V DC and 14.5V DC, but there is no power LED.

[Borgleader]

Re: Acer AL1916

Look at page 32 of the PDF file in your first post.

It tells you to measure U701 and U702 for 3.3V. You should also be seeing 12V DC on pin 5 and 6 at CN701.

I've added a new picture (in attachment) of the green circuit board. At U701 (top left), there isn't actually a component. It's been observed in another thread in this forum: https://www.badcaps.net/forum/showthread.php?t=8257

Even though there wasn't a component in U701, I checked the 3 spots where would've been soldered the pins had they been there (just in case it's helpful) and I also checked the 3 pins for U702. For each of these I used the top screw as my ground.

U701: Top pin: ~0V | Mid pin: ~0V | Bottom pin: ~4.92V
U702: Top pin: ~4.65V | Mid pin: ~3.3V | Bottom pin: ~0V
(Since top/bottom is relative, U701 is top left corner, Blue VGA port is bottom right)

As for CN701, pin 5 doesn't have a cable in it so I didn't manage to get a reading, but pin 6 had a reading of ~14.5V DC.

BTW, on page 45 of the PDF, it shows F902, a fuse.

If this F902 is open (you need to verify with a multimeter), then you will not get 12V DC.

Note the fuse might be on the backside of the board if it is not on the front.

The fuse is indeed on the backside, and again like F901, in the continuity test I got ~0 which is the silent equivalent of "beep".

If the fuse F902 is less than 1.0 ohms, then test diode D921.

Check the diode "in circuit" first. If the readings are suspicious, then you will have to remove it and retest.

If it is a dual diode, it should have two diode symbols pointing at each other towards the middle pin (pin 2).

Put your multimeter on 2000 ohms (if manual range) scale. With power off and lcd unplugged.
...

Now switch to diode mode setting on your multimeter. With power off and lcd unplugged.

...

If the diode tests good, then I suggest measuring the voltage (power on) on pin 2 on the diode (put black on a ground screw). You should get 12V DC.

If you are not getting 12V DC, then either one of or all C923, C931, C925 (see schematic) is bad (as per PCBONEZ back in post #2). Even though they show no visible sign of distress, they can have high ESR (ohm) or be out of uF tolerance.

F902 is ~0.3 ohms (I used a scale of 200, didn't have 20).

D921 (ohm scale 20k, 2k was not enough):
1) put red on pin 1, black on pin 2: 3.96k
2) put red on pin 3, black on pin 2: 3.92k
3) put red on pin 1, black on pin 3: 0k

D921 (diode test):
1) put red on pin 1, black on pin 2: 0.232
2) put black on pin 1, red on pin 2: 1. (the manual says to reverse the leads if i get this, which ends up being 1) )
3) put red on pin 3, black on pin 2: 0.231
4) put black on pin 3, red on pin 2: 1.

Sorry for the delay, I have to pretty much google everything because I've never had to do this before.

[retiredcaps]

Re: Acer AL1916

If the fuse F902 is less than 1.0 ohms, then test diode D921.

Check the diode "in circuit" first. If the readings are suspicious, then you will have to remove it and retest.

If it is a dual diode, it should have two diode symbols pointing at each other towards the middle pin (pin 2).

Put your multimeter on 2000 ohms (if manual range) scale. With power off and lcd unplugged.

1) put red on pin 1, black on pin 2. report ohms.
2) put red on pin 3, black on pin 2. report ohms.
3) put red on pin 1, black on pin 3. report ohms.

Now switch to diode mode setting on your multimeter. With power off and lcd unplugged.

1) put red on pin 1, black on pin 2. report volts.
2) put black on pin 1, red on pin 2. report volts.
3) put red on pin 3, black on pin 2. report volts.
4) put black on pin 3, red on pin 2. report volts.

If the diode tests good, then I suggest measuring the voltage (power on) on pin 2 on the diode (put black on a ground screw). You should get 12V DC.

If you are not getting 12V DC, then either one of or all C923, C931, C925 (see schematic) is bad (as per PCBONEZ back in post #2). Even though they show no visible sign of distress, they can have high ESR (ohm) or be out of uF tolerance.

[retiredcaps]

Re: Acer AL1916

BTW, on page 45 of the PDF, it shows F902, a fuse.

If this F902 is open (you need to verify with a multimeter), then you will not get 12V DC.

Note the fuse might be on the backside of the board if it is not on the front.

[retiredcaps]

Re: Acer AL1916

I got readings of ~4.47V DC (for brown cable), and ~4.92V (for yellow & green cables). The others I couldn't get a reading, the metal part is just too far in.

Look at page 32 of the PDF file in your first post.

It tells you to measure U701 and U702 for 3.3V. You should also be seeing 12V DC on pin 5 and 6 at CN701.

Your pictures of the power board at the offload site have too much glare for me to see the PCB designations. We want a picture that looks like this

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

[Borgleader]

Re: Acer AL1916

(I had originally uploaded my pictures to mediafire to save bandwidth to the server, but since the guidelines suggest using attachments with a max width of 700px i resized it and attached it)

Ok so on this picture, the cables going off to the bottom right come from the yellow circuit board. I put the black probe on the ground screw under them (from this angle) and the red probe in a few of the sockets at the end of the cables.

I got readings of ~4.47V DC (for brown cable), and ~4.92V (for yellow & green cables). The others I couldn't get a reading, the metal part is just too far in.

[retiredcaps]

Re: Acer AL1916

As weird as it may be, the continuity test on my multimeter doesn't "beep", instead when I connect the two probes the value goes from 1. to ~0.

This means it's good right?

The threshold for continuity varies with multimeters. Some beep "good" if the resistance is less than 1.5k ohm.

A good fuse should read less than 1.0 ohms depending on the multimeter.

Since you measure 165V DC across the main filter capacitor that implies the main fuse is good.

The next step is to measure the secondary voltages between the logic board and power board. Use a ground screw for ground. You should see 5V DC and maybe 12V or 19V DC depending on the monitor.

If you don't, then post clear focused pictures of the backside. On the backside, there will likely be a 8 pin or 10 pin IC. We will need its part number.

BTW, pictures should be posted using the following method here.

https://www.badcaps.net/forum/showthread.php?t=1868

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

[Borgleader]

Re: Acer AL1916

Looks in good shape, but did you measure it?
Looking isn't going to eb enough. You'll need to measure, or replace caps, and measure fuses and voltages to fix the problem.

As weird as it may be, the continuity test on my multimeter doesn't "beep", instead when I connect the two probes the value goes from 1. to ~0.

Since the fuse (red box) is soldered so close to the board, I can't test the two pins from the top, so I unscrewed the board again and put one probe on each of the two pins/metal patches on the bottom of the board and I got the same ~0.

This means it's good right?

[smason]

Re: Acer AL1916

Looks in good shape, but did you measure it?
Looking isn't going to eb enough. You'll need to measure, or replace caps, and measure fuses and voltages to fix the problem.

[Borgleader]

Re: Acer AL1916

'3' Pins ?????,should just have '2' !!!
If that is ok,then measure DC Volts acoss the big Brown capacitor,that should be 1.4 times your mains voltage, dependant on what country you are in ??.BEWARE Mains Voltage can be dangerous, so be VERY careful.

http://www.gbaudio.co.uk/data/mains.htm
Canada: 120V @60Hz
Voltage across the biggest of the capacitors is ~165V.

F901 should only have two pins. [look at schematic]
Probably looks like a resistor.
.

It seems I was incorrect, when I looked at it last night the lighting was dim, so today I un-screwed the yellow board and flipped it over it only has 2 pins. Also, the markings on the box read "T2A" and "392". And it looks in good shape.
http://www.mediafire.com/imgbnc.php/...1abf703c6g.jpg
http://www.mediafire.com/imgbnc.php/...9c06cb206g.jpg
http://www.mediafire.com/imgbnc.php/...b6c9b00d6g.jpg

Hi which model of 1916 is this (widescreen or standard)
Only that i may have the correct pdf

My model is AL1916AB, ration 4:3. I've taken a picture of the back sticker with P/N and all in case you need to know anything else. Like I said in the OP, out of the 4 service guides on the Acer website (e,p,v,W) the only one where the green circuit board was the same was the v (which I linked to).
http://www.mediafire.com/imgbnc.php/...8b72360c6g.jpg

[sabre504]

Re: Acer AL1916

Hi which model of 1916 is this (widescreen or standard)
Only that i may have the correct pdf

[PCBONEZ]

Re: Acer AL1916

F901 should only have two pins. [look at schematic]
Probably looks like a resistor.
.

[Rtech]

Re: Acer AL1916

'3' Pins ?????,should just have '2' !!!
If that is ok,then measure DC Volts acoss the big Brown capacitor,that should be 1.4 times your mains voltage, dependant on what country you are in ??.BEWARE Mains Voltage can be dangerous, so be VERY careful.