No power on a Acer AL1916

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  • Xeoncross
    replied
    Re: No power on a Acer AL1916

    A photo of the logic board is in my last post. I tried to take another picture but my camera is out of batteries so I'm charging it now. Let me know and I'll take a photo if needed.

    Leave a comment:


  • PlainBill
    replied
    Re: No power on a Acer AL1916

    Originally posted by Xeoncross
    Today I got a fluke 87 from a friend and found that the capacitance setting only goes to 5uF. I tried checking for a short on any of the caps using ohm and they seemed fine.

    Anyway, I followed each step here and these are my results:

    Code:
    Power Board #1 Large Capacitor - 166 volts
    Black - 0.012
    Brown - 4.49
    Red - 14.52
    Orange -0.00
    Yellow - 4.93
    Green - 4.93
    Blue - 0.00
    Black - 0.00
    Code:
    Logic Board: (S/N: 715G1558-1-ac)
    Left - 3.28
    Middle - 2.56
    Right - 2.59
    
    Top - 4.64
    Middle - 3.28
    Bottom - 0.00
    I got almost the same exact results from these steps as RobertoIsRad. So I'm also assuming the logic board is bad. However, unlike RobertoIsRad my LCD powers up and the backlight and LED both come on. Nevertheless, there is no acer logo let alone any kind of image or response from the menu buttons. So apparently the power is working at least enough to light-up the screen.

    I tried the screwdriver short on U406 but it didn't seem to effect anything since the screen already powers up.

    I'm wondering what to test next. After following all the instructions listed here I have come to the conclusion that I should just try replacing all caps and see if that works. The problem is that none of the caps look bad except for the slightest budge on C0612 (1000 uF @ 25V) and C0604 (1000 uF @ 16V) shown below.



    I found a copy of the logic board but it's no longer for sale.
    There are two possible approaches to this. One is to replace all the caps on the power supply board. Remember, bulging / no bulging is not a definitive sign of the quality of a cap. Any cap that is bulging is bad. One that is not bulging may or may not be bad.

    As I recall, this logic card has multiple processors. I suggest checking the voltages on all the voltage regulators on the logic card. Attach a picture if you want me to point them out.

    PlainBill

    Leave a comment:


  • Xeoncross
    replied
    Re: No power on a Acer AL1916

    Today I got a fluke 87 from a friend and found that the capacitance setting only goes to 5uF. I tried checking for a short on any of the caps using ohm and they seemed fine.

    Anyway, I followed each step here and these are my results:

    Code:
    Power Board #1 Large Capacitor - 166 volts
    Black - 0.012
    Brown - 4.49
    Red - 14.52
    Orange -0.00
    Yellow - 4.93
    Green - 4.93
    Blue - 0.00
    Black - 0.00
    Code:
    Logic Board: (S/N: 715G1558-1-ac)
    Left - 3.28
    Middle - 2.56
    Right - 2.59
    
    Top - 4.64
    Middle - 3.28
    Bottom - 0.00
    I got almost the same exact results from these steps as RobertoIsRad. So I'm also assuming the logic board is bad. However, unlike RobertoIsRad my LCD powers up and the backlight and LED both come on. Nevertheless, there is no acer logo let alone any kind of image or response from the menu buttons. So apparently the power is working at least enough to light-up the screen.

    I tried the screwdriver short on U406 but it didn't seem to effect anything since the screen already powers up.

    I'm wondering what to test next. After following all the instructions listed here I have come to the conclusion that I should just try replacing all caps and see if that works. The problem is that none of the caps look bad except for the slightest budge on C0612 (1000 uF @ 25V) and C0604 (1000 uF @ 16V) shown below.

    Originally posted by PlainBill
    5V supply
    1000 uF @ 16V C924
    470 uF @ 16V C926

    12V supply
    1000 uF @ 25V C923, C931 (yes, two of them)
    470 uF @ 25V C925

    SMPS supply
    100 uF @ 25V C906
    47 uF @ 25V C909

    Inverter
    470 uF @ 25V C203
    I found a copy of the logic board but it's no longer for sale.
    Attached Files
    Last edited by Xeoncross; 05-20-2010, 08:10 PM.

    Leave a comment:


  • sceva
    replied
    Re: No power on a Acer AL1916

    Replaced the part at U406 with a MAX810MTRG0SCT-ND from DigiKey, and it is working beautifully. I did test the voltages on the bottom two pins after installing, and with a DMM, I never saw any voltages on either of the two legs. I held the probes on each pin and cycled power. It could be that the meter would not read if it was only on for a few milliseconds?

    I also wanted to express my gratitude again for everyone's help on this site. I was ready to scrap this monitor when I saw that the problem was on the logic board, as most problems in this part of a monitor are above my skill level. After searching and finding this post I was able to fix the problem with a 58 cent part. Amazing.

    Leave a comment:


  • PlainBill
    replied
    Re: No power on a Acer AL1916

    Originally posted by sceva
    Thanks for the update. I agree that it is usually best to replace parts, as the reason they are there may not be initially apparent. Although... if designers and builders didn't make mistakes, we wouldn't have much to repair?
    That is a point I have just been thinking about. Sometimes an improved design makes parts unnecessary. Designers don't always read the application notes carefully. It is not beyond the realm of possibility that the reset controller is there because the lead designer KNEW this line of processors always required one. It is also not beyond the realm of possibility that there was a design error on the reset controller.

    PlainBill

    Leave a comment:


  • sceva
    replied
    Re: No power on a Acer AL1916

    Thanks for the update. I agree that it is usually best to replace parts, as the reason they are there may not be initially apparent. Although... if designers and builders didn't make mistakes, we wouldn't have much to repair?

    Leave a comment:


  • PlainBill
    replied
    Re: No power on a Acer AL1916

    Originally posted by sceva
    I laughed out loud at this comment. PlainBill can be quite the character....

    I found this thread while researching a problem with a ViewSonic VG920, which must have the same or very similar logic board. Following Bill's advice, I found the component at U406 to be faulty. I promptly ordered a replacement from digi-key. Then I finished reading the thread and saw the comment about removing the component and it works. I wanted to test and make sure there wasn't other problems on the inverter side, so I removed the component (with a soldering iron, not a rock - I couldn't find a rock the proper size...), powered it up, and it works perfectly.

    So, is there a danger in not having the component installed? What does this part do?

    Thanks for the info and the laugh!
    I always recommend looking up the datasheets when you have a question like that. Unfortunately, a detailed datasheet is not available for the processor, so I can't get an idea of how important the reset controller really is.

    Background: Many processors generate voltages internally. Way back in antiquity the 8080 required three power supplies (+12, +5, -5 volts). Later processors generated these voltages internally via charge pumps. Since the processor could not begin operation until the internal supplies were stable, some means of holding the processor in reset was required. In the IBM PC, XT, AT, and later compatible systems this was accomplished by the power supply. The reset line would stay active until several milliseconds after all power supply outputs were stable.

    The reset controller Does something similar. It monitors it's input voltage, and holds the reset line active (either high or low, depending on dash number) until a certain number of milliseconds after the input voltage rises above the threshold (which also varies by dash number).

    As to what will happen if you remove the reset controller, I don't know. In general, leaving an input to a processor 'floating' is a big No-No (ref 'Rowan and Martin's Laugh-In). However, many processors have internal pullups on critical lines. Some even have their own internal reset controllers. The fact that the processor works with the reset controller removed is a good sign.

    As I have stated, monitors are not built on a 'cost plus' basis. I am certain the designer believed it necessary to have a reset controller. Whether or not they are correct is another matter.

    PlainBill

    Leave a comment:


  • sceva
    replied
    Re: No power on a Acer AL1916

    Originally posted by PlainBill
    Why not go caveman and just smash it with a rock?
    I laughed out loud at this comment. PlainBill can be quite the character....

    I found this thread while researching a problem with a ViewSonic VG920, which must have the same or very similar logic board. Following Bill's advice, I found the component at U406 to be faulty. I promptly ordered a replacement from digi-key. Then I finished reading the thread and saw the comment about removing the component and it works. I wanted to test and make sure there wasn't other problems on the inverter side, so I removed the component (with a soldering iron, not a rock - I couldn't find a rock the proper size...), powered it up, and it works perfectly.

    So, is there a danger in not having the component installed? What does this part do?

    Thanks for the info and the laugh!

    Leave a comment:


  • Wrog
    replied
    Re: No power on a Acer AL1916

    Originally posted by Xeoncross
    Ok, I want to replace the C0612 (1000 uF @ 25V) and the C0604 (1000 uF @ 16V).

    After reading all the forum FAQ's and tutorials I'm still having trouble figuring out what types of caps I need. Maybe someone can let me know if this is right.
    Originally posted by PlainBill
    A recommended approach is to make a list showing the value, voltage, diameter, and height of the caps being replaced. (A shortcut is to only measure the diameter of caps close to one another, and note the maximum permissible height for the caps.)
    As PB says, make a list of the caps you want to replace, and someone will make suggestions on which to buy. Reason being, there are MANY MANY different caps out there (as you've seen by searching) and you need to make sure the replacements will both work AND fit!

    Leave a comment:


  • PlainBill
    replied
    Re: No power on a Acer AL1916

    Originally posted by Xeoncross
    Ok, I want to replace the C0612 (1000 uF @ 25V) and the C0604 (1000 uF @ 16V).

    After reading all the forum FAQ's and tutorials I'm still having trouble figuring out what types of caps I need. Maybe someone can let me know if this is right.

    C0612 (1000 uF @ 25V)
    http://search.digikey.com/scripts/Dk...&name=P5544-ND

    C0604 (1000 uF @ 16V)
    http://search.digikey.com/scripts/Dk...&name=P5533-ND

    Again, here is a shot of them. (Front left and back right)
    No.

    Read the FAQ on 'Which caps should I use?'.
    Read the FAQ on inserting pictures.
    Read the thread I linked to on selecting caps.
    As a minor point, I don't see signs of bulging, but you ARE closer to the caps than I am.

    PlainBill

    Leave a comment:


  • Xeoncross
    replied
    Re: No power on a Acer AL1916

    Ok, I want to replace the C0612 (1000 uF @ 25V) and the C0604 (1000 uF @ 16V).

    After reading all the forum FAQ's and tutorials I'm still having trouble figuring out what types of caps I need. Maybe someone can let me know if this is right.

    C0612 (1000 uF @ 25V)
    http://search.digikey.com/scripts/Dk...&name=P5544-ND

    C0604 (1000 uF @ 16V)
    http://search.digikey.com/scripts/Dk...&name=P5533-ND

    Again, here is a shot of them. (Front left and back right)

    Leave a comment:


  • PlainBill
    replied
    Re: No power on a Acer AL1916

    Originally posted by jmb2112
    I recently was given an AL1916 monitor with the same problem-no power, no led light. I confirmed it was the same problem with U406 on the main board (I shorted bottom two pins and hit power button - got lit up screen with acer logo). Was going to order part but further googling (foreign language forums) revealed that U406 (Max810g part) could just be removed and monitor would work. I used a needle nose plier and just pulled it off the board (I guess you could just break it up, also). When plugged in, the monitor immediately powered up without hitting the power button, but will turn off and on using power button. I've only used it for a day, but it worked fine. A much easier fix than trying to solder a surface mount component the size of the tip of a pencil with three leads. Any comments appreciated on this method of repair.

    Thanks for your posts! Jim
    Why not go caveman and just smash it with a rock? Modern man has invented this tool called a Soldering Iron that we find useful for removing components.

    I'm thinking the look on your face would have been priceless if the monitor had NOT started right up.

    PlainBill

    Leave a comment:


  • jmb2112
    replied
    Re: No power on a Acer AL1916

    I recently was given an AL1916 monitor with the same problem-no power, no led light. I confirmed it was the same problem with U406 on the main board (I shorted bottom two pins and hit power button - got lit up screen with acer logo). Was going to order part but further googling (foreign language forums) revealed that U406 (Max810g part) could just be removed and monitor would work. I used a needle nose plier and just pulled it off the board (I guess you could just break it up, also). When plugged in, the monitor immediately powered up without hitting the power button, but will turn off and on using power button. I've only used it for a day, but it worked fine. A much easier fix than trying to solder a surface mount component the size of the tip of a pencil with three leads. Any comments appreciated on this method of repair.

    Thanks for your posts! Jim

    Leave a comment:


  • PlainBill
    replied
    Re: No power on a Acer AL1916

    Originally posted by Xeoncross
    Oh, I forgot to mention that I also need to know what exactly to buy. I was checking out the shopping guide and then I realized that I didn't know what type of caps these were. I also included another shot of the other capacitors on the board just in case.
    Two threads in the FAQ subforum will help you, 'Which Caps Should I buy?', and 'Where can I buy caps?'. Note that the list of series in these threads is reversed from real life - the best caps are on the right.

    A recommended approach is to make a list showing the value, voltage, diameter, and height of the caps being replaced. (A shortcut is to only measure the diameter of caps close to one another, and note the maximum permissible height for the caps.)

    This post shows how to select the appropriate caps at Digikey. A similar technique will work at Mouser.

    If you wish, post the list and the replacement you chose if you wish to have your choices verified.

    PlainBill

    Leave a comment:


  • Xeoncross
    replied
    Re: No power on a Acer AL1916

    Oh, I forgot to mention that I also need to know what exactly to buy. I was checking out the shopping guide and then I realized that I didn't know what type of caps these were. I also included another shot of the other capacitors on the board just in case.
    Attached Files

    Leave a comment:


  • Xeoncross
    replied
    Re: No power on a Acer AL1916

    Just disassembled my "Acer AL1916A B" like above and I belive that I have the same problem with the power supply board. I'm a real DIY guy when it comes to PC's so I'm interested in following the advice here and replacing the caps.

    The only problem is that I have never soldered anything.

    Anyway, the only caps that seem to be bulging are the C0612 (1000 uF @ 25V) and the C0604 (1000 uF @ 16V) as shown below. The video board looks good. I'm hoping that I can just remove them an then solder replacement caps into their place. The depth of my knowledge is http://www.youtube.com/watch?v=on_2CP52cW4 so let me know if I'm about to shoot myself in the foot and need to go learn more first.
    Attached Files

    Leave a comment:


  • PlainBill
    replied
    Re: No power on a Acer AL1916

    Originally posted by RobertoIsRad
    Thank you so much Bill!!! I'm sorry it took so long for an update... The first monitor I replaced all the caps and there was no change. So Then I put in the new controller and it turned on beautifully! Then I replaced the controller in the other one (I'll replace the caps later) and same thing, Works Perfect! So I thank you once again, I couldn't have done it without you! I now have two perfectly fine monitors
    Glad to hear it!!!

    PlainBill

    Leave a comment:


  • RobertoIsRad
    replied
    Re: No power on a Acer AL1916

    Thank you so much Bill!!! I'm sorry it took so long for an update... The first monitor I replaced all the caps and there was no change. So Then I put in the new controller and it turned on beautifully! Then I replaced the controller in the other one (I'll replace the caps later) and same thing, Works Perfect! So I thank you once again, I couldn't have done it without you! I now have two perfectly fine monitors

    Leave a comment:


  • PlainBill
    replied
    Re: No power on a Acer AL1916

    Originally posted by RobertoIsRad
    Ok great. I'll probably order these either today or tomorrow. Then it will take a few days to get them. I'll let you know how it goes. Thanks again!
    Well, at least you're close to Digikey. At one time I lived at the opposite end of the Twin Cities (Mound). Can't say that I miss the snow. High today is only up to the mid 70's.

    PlainBill

    Leave a comment:


  • RobertoIsRad
    replied
    Re: No power on a Acer AL1916

    Ok great. I'll probably order these either today or tomorrow. Then it will take a few days to get them. I'll let you know how it goes. Thanks again!

    Leave a comment:

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