Acer AL2416W sd black screen after "ACER"

[cammac725]

This is my first post, after having learned (or tried to learn) much from you all. Truly a great resource and community.

I am trying to repair an Acer AL2416w sd that would start up, show the word "ACER" then a black screen and the power light would change from green to yellow. I had no dim image using a flashlight. None of the caps on the 3 boards are domed or "look" bad.

I followed the other threads about this monitor, and decided that, even though there was no visual evidence of failure, I would replace the caps on the power board. Lo and behold, progress! Now the power button stays green and there is a dim image when using a flashlight. So I am left with 2 possibilities (I think). The inverter board or backlight bulb(s).

I think I am getting close to my limit on diag skills here and could use a little help determining which. It looks like there are 6 bulbs on this model. Could one bad bulb cause this? How do I test a bulb? Continuity?

All the caps on the inverter board "look" ok. Can someone point me in the right direction? I'm not sure about the MOSFETs (or even which ones they are). Yeah, I'm a little green.

TIA

PS I've attached photos of the inverter board.

[jetadm123]

Re: Acer AL2416W sd black screen after "ACER"

This is my first post, after having learned (or tried to learn) much from you all. Truly a great resource and community.

I am trying to repair an Acer AL2416w sd that would start up, show the word "ACER" then a black screen and the power light would change from green to yellow. I had no dim image using a flashlight. None of the caps on the 3 boards are domed or "look" bad.

I followed the other threads about this monitor, and decided that, even though there was no visual evidence of failure, I would replace the caps on the power board. Lo and behold, progress! Now the power button stays green and there is a dim image when using a flashlight. So I am left with 2 possibilities (I think). The inverter board or backlight bulb(s).

I think I am getting close to my limit on diag skills here and could use a little help determining which. It looks like there are 6 bulbs on this model. Could one bad bulb cause this? How do I test a bulb? Continuity?

All the caps on the inverter board "look" ok. Can someone point me in the right direction? I'm not sure about the MOSFETs (or even which ones they are). Yeah, I'm a little green.

TIA

PS I've attached photos of the inverter board.

Verify inverter is getting voltage (12-24V?) from power board.

Check fuse F3 at the bottom of your photo.

Check mosfet Q5 (p5504edg, should be four of these mosfets) and the 3 others for shorts.

Also, post a good closeup of the entire inverter board.

[cammac725]

Re: Acer AL2416W sd black screen after "ACER"

A thousand apologies...and a hearty thank you. I found that I had left the connector to the inverter board soft set. Fully seated now...and back to life.

Again thank you for your time.

[cammac725]

Re: Acer AL2416W sd black screen after "ACER"

Premature celebration, something is still not right.

If the monitor sits for a few hours and I restart it, there is no backlighting...only a dim image by flashlight. There is 24 volts to the inverter board, all fuses on the inv. board are good. Haven't tested the MOSFETs yet...

At some point in my head-scratching, I forgot the monitor was still on and I disconnected the connector off the power board that goes to the inverter (the one I thought was soft set before). When I reconnected it, there was a small spark at the connector and the monitor came to life (backlight and all) and has stayed working. Gently wiggling the connector produces no flickering or any shutting off, so I don't think there are any loose joints.

The voltages (and continuity to gnd) to the inverter are the same whether the backlight is working or not.

If I shut it off again and let it sit. On restart, it does the same thing: no backlight, then unplug/re-plug and it works. It sounds like a voltage spike when it gets connected is making something start up. This also makes me think the MOSFETs are not shorted (can they be shorted intermittently?)

Does any of this sound familiar or lead to a conclusion?

[PlainBill]

Re: Acer AL2416W sd black screen after "ACER"

Normally the inverter is controlled by the logic card. By any chance is there a legend indicating the pinout of CN1 on the inverter? The pin you are looking for would be called BL_ON or something similar.

PlainBill

[jetadm123]

Re: Acer AL2416W sd black screen after "ACER"

Premature celebration, something is still not right.

If the monitor sits for a few hours and I restart it, there is no backlighting...only a dim image by flashlight. There is 24 volts to the inverter board, all fuses on the inv. board are good. Haven't tested the MOSFETs yet...

At some point in my head-scratching, I forgot the monitor was still on and I disconnected the connector off the power board that goes to the inverter (the one I thought was soft set before). When I reconnected it, there was a small spark at the connector and the monitor came to life (backlight and all) and has stayed working. Gently wiggling the connector produces no flickering or any shutting off, so I don't think there are any loose joints.

The voltages (and continuity to gnd) to the inverter are the same whether the backlight is working or not.

If I shut it off again and let it sit. On restart, it does the same thing: no backlight, then unplug/re-plug and it works. It sounds like a voltage spike when it gets connected is making something start up. This also makes me think the MOSFETs are not shorted (can they be shorted intermittently?)

Does any of this sound familiar or lead to a conclusion?

I agree with you that if the backlights stay running , then the mosfets are probably ok. I would suggest that you NOT try plugging the connector in while power is on, since this will cause a voltage spike which can cause severe damage to the inverter board. It almost sounds like you have a bad CCFL tube and that "jolt" in voltage is enough to cause it to turn on. Other members will probably suggest that you get hold of a good CCFL tube and substitute it one at a time with the current tubes. By doing so, once you get all the tubes to light, then you've isolated the bad tube.

[cammac725]

Re: Acer AL2416W sd black screen after "ACER"

@PlainBill:

I found a schematic/pin-out diagram for the monitor. I have 3v on the BL ON/OFF wire on the inverter. I also have no voltage at the bulb connectors.

@jetadm123:

Would any old CCFL tube do? I could yard one out of a different monitor I've got lying around.

[retiredcaps]

Re: Acer AL2416W sd black screen after "ACER"

@jetadm123:

Would any old CCFL tube do? I could yard one out of a different monitor I've got lying around.

You don't have to remove the old ccfl tube. Just drag the old monitor close enough to the Acer (don't let the two touch) and stretch Acer ccfl connector to the old lcd ccfl.

[jetadm123]

Re: Acer AL2416W sd black screen after "ACER"

@PlainBill:

I found a schematic/pin-out diagram for the monitor. I have 3v on the BL ON/OFF wire on the inverter. I also have no voltage at the bulb connectors.

@jetadm123:

Would any old CCFL tube do? I could yard one out of a different monitor I've got lying around.

I would not attempt to measure the voltage at the bulb connectors. This voltage is around 700-900VAC and can damage your meter!

[alexanna]

Re: Acer AL2416W sd black screen after "ACER"

@PlainBill:

I found a schematic/pin-out diagram for the monitor. I have 3v on the BL ON/OFF wire on the inverter.

Would any old CCFL tube do? I could yard one out of a different monitor I've got lying around.

I am unsure on this monitor; it might use a long horseshoe ccfl so just any ccfl may not work.
If you try another ccfl and you find the problem, well don't do the rest of this.
On inverters that are separate from power supplies on the connector there several voltages
Higher supply voltage somewhere around 12to24volts.
Several ground pins.
A back light on signal, usually 3vlots on and close to 0 volts off.
A dim pin and if I remember correctly about 1 volt full brightness and a higher voltage for dimmer.
PlainBill asked you to check the back light on siginal,I would suggest you check this with the monitor off, and again as you power the monitor on. Also verify the other voltages at the connector.
I am wondering if what's happening when you plug in the connector your flexing something on the printed circuit board. You could try with something very well insulated flexing various points of the power supply and inverter, see if you can recreate the problem.
Al.

[cammac725]

Re: Acer AL2416W sd black screen after "ACER"

I would not attempt to measure the voltage at the bulb connectors. This voltage is around 700-900VAC and can damage your meter!

Thanks for the warning! But since I DID check it, while it wasn't backlit, and had no voltage (and my meter still works) that tells me the problem is before the bulbs.

Has anyone found a source for this inverter board? I cannot find one anywhere I've looked. I contacted Acer and the sources they suggested told me it would be very hard to find one.

[cammac725]

Re: Acer AL2416W sd black screen after "ACER"

I am unsure on this monitor; it might use a long horseshoe ccfl so just any ccfl may not work.

Thanks for all the suggestions, Al. There are six connectors, so I believe it has 6 CCFLs.

PlainBill asked you to check the back light on siginal,I would suggest you check this with the monitor off, and again as you power the monitor on. Also verify the other voltages at the connector.

I have 0v with monitor off and ~3v when powered on.

I am wondering if what's happening when you plug in the connector your flexing something on the printed circuit board. You could try with something very well insulated flexing various points of the power supply and inverter, see if you can recreate the problem.
Al.

When I plugged in the connector, I was barely touching the pins to each other. I don't think there was enough force to flex anything. But I did check that anyway. Flexing and wiggling did nothing to indicate any fault there.

[jetadm123]

Re: Acer AL2416W sd black screen after "ACER"

Thanks for the warning! But since I DID check it, while it wasn't backlit, and had no voltage (and my meter still works) that tells me the problem is before the bulbs.

Has anyone found a source for this inverter board? I cannot find one anywhere I've looked. I contacted Acer and the sources they suggested told me it would be very hard to find one.

A bad CCFL tube will be seen by the CCFL controller, which in turn will shut down the power supply. Therefore, just because you didn't see voltage at the tube connector doesn't mean the inverter is bad. So, a bad CCFL tube is still a valid possibility.

[cammac725]

Re: Acer AL2416W sd black screen after "ACER"

I ended up replacing the 8 small 35v, 100uf caps on the inverter board. Everything has been working fine since then. 30+ start-ups, from cold start to immediate reboot. Monitor works as advertised every time.

Thanks for all your help and input.

Cameron

[azghan]

Re: Acer AL2416W sd black screen after "ACER"

hi all,

just to share, i had same issue, i replaced 4 caps of 35v 100uf 105c, and its back to life.

thanks ppls.

[lvkerr]

Re: Acer AL2416W sd black screen after "ACER"

Hi all,
I have replaced all the 100mfd capactors and 2 mosfets as well as the fuse on the inverter board with no result. Not getting 24V from the power board. Can anyone tell me were I can get hold of a connector diagram so that I can check all the voltages. Better still a circuit of the inverter and power board.
Thanks

[alexanna]

Re: Acer AL2416W sd black screen after "ACER"

https://www.badcaps.net/forum/showth...ht=2416&page=2
Look over this thread see if this is your monitor.If it is,There are some pin voltages listed that may be helpful.
check these voltages. https://www.badcaps.net/forum/showpo...5&postcount=36

[lvkerr]

Re: Acer AL2416W sd black screen after "ACER"

Thanks for the link to the voltage tables. I will check them out today and let you know how I got on

[lvkerr]

Re: Acer AL2416W sd black screen after "ACER"

Checked all the voltages against the table and found them to be correct. Fault turned out to be poor soldering of one mosfet to the PCB. Didn't have enough heat in my soldering iron. Monitor now works like new. Used Fairchild FDD5614 and FD5612 mosfets as I couldn't buy the originals. Replaced 10 100mfd 35V electrolytic capacitors with low ESR 105C types. Surface mount fuse F2 1.5A was also replaced. All components came from Farnell.

Thanks for a marvelous forum. It enabled me to repair the monitor for less than $20

[bigmuddyfoot]

Re: Acer AL2416W sd black screen after "ACER"

I have the acer 2416w with no black light, looks like i got some bad caps that need to be replaced does anyone have some model numbers of the parts i need to fix them?

it also looks like i need new mossfetts