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Half success on AL1716

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    Half success on AL1716

    When I first got the AL1716 the back light flashed every few seconds and the power led flashed from green to yellow/orange.

    Verified:
    120v AC at bridge
    160v DC at main capacitor
    5v on 5v side, adding a good cap didn't improve
    12v on 12v side, adding a good cap didn't improve
    Short “5.ON/OFF” to “1.VCC5V” back light still flashes
    4 electrolytic capacitors on display board check good
    Display chip TSU16AK-LF gets very hot
    No logo on display
    No semiconductor shorts on either the power supply or the video board.

    Shorting “5.ON/OFF” to “1.VCC5V” should eliminate the video board 79040130 or the power/PWM board 79040140 as faulty. If the back light still flashes then the PWM is faulty but the logo should be seen. If the backlight stops flashing then the video board is faulty and no logo is likely.

    I short the screen on yet the back light still flashes and no logo is seen which means that both boards are faulty. This is not good considering that the AL1716b is not popular enough to have spare parts on eBay.

    I left it several days then went testing again to see if there was something that I had missed. I noticed that the MOSPEC SRF1040C D805 diode array on the 5v output only has 0.181 voltage drop in circuit and 0.141 voltage drop out of circuit which seemed a bit low to me.

    Knowing that SMPS diode arrays of the same polarity are mostly interchangeable I raid one of my busted power supplies from a Compaq EVO D510S and select a ST BWY51. The SRF1040C has an insulated mount and the BWY51 does not so I must bring along the insulator. With the BWY51 installed the outputs read 5.08v and 13.30v, the 12v line is over 1v higher than before. The video chip doesn't overheat as fast. Shorting the back light control line to 5v lights the back light without flashing. The video board dims the monitor at the times where it would have blanked the back light if I wasn't shorting the back light on.

    Now the power supply and inverter work! It could have been a bad solder or a leaking diode.

    The power button is able to turn the monitor off but it doesn't behave well when it goes back on. So the video board does something intelligent but doesn't work well enough to show an image. Pin 8 of U103 and U106 have 5v on them. SMD decoupling caps C140, C142, C144, and C138 have 3.3v on them. Then I notice a 3 pin chip U102 on the video board called AS1117L-33 with 5v and 3.3v on two legs. The data sheet shows that it's a 1 amp regulator available in voltages 1.8v, 2.5v, 3.3v, 5.0v, and adjustable. Then I see a similar chip U101 AS1117L-18 which should be a 1.8v part but is outputting 4.0v. SMD decoupling cap C134 has 4.0v. C106 and C148 have 4.0v which is the output of the 1.8v regulator. C148 and C101 has 5v which is the input to the 1.8v regulator. The 1.8v regulator internals must be shorted on to get max output.

    Now that I know what the voltages are and where they come from I can easily figure out where all these voltages are used. With the monitor unpowered and the DMM on diode test I hook one probe to the output of a voltage regulator and run the other probe across all the chips and other important devices. 5v is used on U105, U106, U103, and not used on U104. 3.3v and 1.8v is used all over U104 but not any others.

    With the power back on going along C137 to C125 I see 3.3v, 4.0v, and 5v so 4.0v is definitely going into the video chip from the defective 1.8v regulator. With the part out the video chip gets hot really fast. The exact part is not available on eBay but a LM1117 1.8v seems to be an exact match so I'll get that one. But that China part is so far away. If only there was a way to verify that the new regulator would fix the problem.

    I need a regulated 1.8v and I know that some Pentium IV chips run around that voltage so I start testing motherboards. Turns out those old 1.7Ghz P4 run at 1.73 volts so I rig up some Cat 5 wire to get power from the motherboard setup to the monitor setup and continue testing. The video chip doesn't get hot when only 1.73v is supplied. Unfortunately we have two independent power supplies that go on at different times. After some testing trials and errors I power up the 1.73v motherboard supply then quickly power up the monitor supply:

    The Acer logo shows!

    The power supply failure might cause the video board failure. With both failed I get a complex green/yellow power L.E.D. and back lighting sequence which appears to change over time because the power cycling and the video errors are running together and can be affected by the buttons because the video chip is partially working.

    A quick look at the Dell 1702FP LG L1800FPK board shows that it has a 1117S25 2.5v regulator, a BA033 3.3v regulator, and a KA78M05R (78M05, 7805) 5v regulator that pulls from the 12v source. Looks like all these video boards have one or more regulators that are susceptible to power supply failures and easy to fix.

    The victory is short lived. I put a new 1.8v regulator in and the Acer logo shows clear. Unfortunately the VGA input is out of sync. Perhaps the 1.8v lines running too long at 4.0v burned out part of the display chip.
    Attached Files
    sig files are for morons

    #2
    Re: Half success on AL1716

    Heck of a job of troubleshooting!!!

    PlainBill
    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

    Comment


      #3
      Re: Half success on AL1716

      Hello all - thought I would necropost this back up to the top. I have two of these AL1716B's on the bench right now, and I thought my own observations might be useful for future searches.

      Both of mine were rescued from the junk pile, and they both had issues.

      Monitor 1 - same symptoms as the original post. Backlight flashes, no logo. Failed Su'scon 1000uF 10V caps were found next to the 5V output diode pack. Replaced failed caps with Nippon Chemi-Con 1000uF 16V KY's from a power supply I blew up for jonnyGURU.com. Shorted the screen on - inverter stays on, still no logo. Measured 4V and 5V at U101. Diagnosis... defective video board. No plans on fixing.

      Monitor 2 - powered up with the Acer logo to an all white screen. PSU section made loud chirping noises on power up. Failed Su'scon 1000uF 10V caps were again found next to the 5V output diode. Replaced with Nippon Chemi-con KY. Swapped over the LCD from the other AL1716B as a precaution. I wasn't going to bother trying to fix that one anyway, so why not?

      Results - monitor #2 is now working perfectly. Seems I caught that one in time before it could fry the video board. Monitor #1 is a big paperweight, but with a working PSU board. At least it has one usable part left.

      I didn't check the display chip on #1 to see if it was running hot before recapping the PSU. All I can report on that front is that it's not running hot now.

      Comment


        #4
        Re: Half success on AL1716

        Originally posted by severach
        With the monitor unpowered and the DMM on diode test I hook one probe to the output of a voltage regulator and run the other probe across all the chips and other important devices.
        In retrospect this is probably what destroyed the video board. Back when 5v was the norm a couple of volts out of a continuity tester was nothing special. With signal voltages going as low as 0.5v they are the probes of death.

        I had a WD 250GB with a broken SATA data connector. I knew it worked because I was able to run it when I still had the plastic nub lodged in the SATA cable. With all my new tools I retrofitted it with a connector from a bad drive. I had some problems with solder bridging on the power connector so I started testing for continuity. Once I saw a pattern on the power connector I looked up the pinouts and sure enough the spots that were bridging were bridged on the board so it didn't matter. The probes didn't cause any trouble on a connector that sees 3.3v-12v.

        Then I tried probes on the SATA connector. No problems with shorting but on the first power up the drive didn't communicate. When I saw the 0.5v SATA signal level I knew me and my probes of death were the cause. I noticed that the SATA signals ran into a TQFP-60 fine pitch chip Marvell 88i8030-TBC SATA interface. I transferred another from a junk board and now the drive works.
        sig files are for morons

        Comment


          #5
          Re: Half success on AL1716

          Interesting... I never tried doing that with #1. Maybe there's hope for it yet. I decided I had to know for sure, so I have a batch of ten 1.8V LM1117's on order now. They were cheap enough to make it worth the gamble.

          Thanks for all your hard work troubleshooting

          Comment


            #6
            Re: Half success on AL1716

            Fascinating troubleshooting, thanks for sharing.

            Originally posted by severach
            With signal voltages going as low as 0.5v they are the probes of death.
            Hmm I hadn't given much thought to the voltages used with the diode/continuity tests, definitely something to keep in mind.
            36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

            Comment


              #7
              Re: Half success on AL1716

              Just an update. My new LM1117's are here, and U101 has been replaced after a brief fight with my soldering iron.

              Monitor #1 is now fully working, as far as I can tell. So, this one was a complete success. Now if I could only get that HP VS17 fixed, I'd be happy.

              Comment


                #8
                Re: Half success on AL1716

                Originally posted by Oklahoma Wolf
                ...Now if I could only get that HP VS17 fixed, I'd be happy.
                Do you have a thread for this unit?
                There are 10 kind of people in this world: those that understand binary, and those who don't.
                • ASUS ROG Maximus IX Code
                • Intel Core i5-7600K 3.8GHz
                • 16gb GSKILL TridentZ RGB DDR4-3200
                • 1 M2 SSD + 2 WD Blue 1TB (Mirrored)
                • Windows 10 Pro x64
                • GeForce GT1050
                  2 x Acer KA240H + 1 Vewsonic VP2130 21 (a cap replacement job )

                Comment


                  #9
                  Re: Half success on AL1716

                  Yep - it got buried with no responses.

                  https://www.badcaps.net/forum/showthread.php?t=9599

                  Comment


                    #10
                    Re: Half success on AL1716

                    Originally posted by Oklahoma Wolf
                    Yep - it got buried with no responses.

                    https://www.badcaps.net/forum/showthread.php?t=9599
                    I remember reading it. But I can't help on that.I'm not that good. Maybe PlainBill can help you on this one ...
                    There are 10 kind of people in this world: those that understand binary, and those who don't.
                    • ASUS ROG Maximus IX Code
                    • Intel Core i5-7600K 3.8GHz
                    • 16gb GSKILL TridentZ RGB DDR4-3200
                    • 1 M2 SSD + 2 WD Blue 1TB (Mirrored)
                    • Windows 10 Pro x64
                    • GeForce GT1050
                      2 x Acer KA240H + 1 Vewsonic VP2130 21 (a cap replacement job )

                    Comment


                      #11
                      Re: Half success on AL1716

                      No problem - that one's got extra bells and whistles, which is why I keep ending up pounding my head on hard surfaces whenever I try to get it fixed. Ah well - I got the last Acer AL1716B fixed... it's a better monitor anyway. The HP has such a slow response time it's painful to watch video on.

                      Comment


                        #12
                        Re: Half success on AL1716

                        Awsome write-up, I have one of these on the bench as well. Mine has a power light that flashes from green to amber quickly and the screen just flashes, no logo. I replaced the caps, 1000uf and 470uf. do you have a diagram for this board?

                        Comment


                          #13
                          Re: Half success on AL1716

                          Originally posted by BullPar
                          Awsome write-up, I have one of these on the bench as well. Mine has a power light that flashes from green to amber quickly and the screen just flashes, no logo. I replaced the caps, 1000uf and 470uf. do you have a diagram for this board?
                          A number of the service manuals for the different variants can be found at Elektrotanya.

                          PlainBill
                          For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                          Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                          Comment


                            #14
                            Re: Half success on AL1716

                            Hi, sorry for my english.
                            I have the same Al1716 on "severach" Photos. P/N ET.1716P.014
                            I have Problem with TSU16AK. My chip U101 AS1117L-18 have only 1,2V.
                            If is Power not 5V, but only 4V is Logic OK. The Acer logo shows clear, unfortunately the VGA input is out of sync.
                            If Power is 5V, that LED Power still flashes green/red.

                            I need Schematics, but Elekrotrotanya have only other Models.
                            Can you help me?

                            Comment


                              #15
                              Re: Half success on AL1716

                              Originally posted by pavedom View Post
                              My chip U101 AS1117L-18 have only 1,2V. If is Power not 5V, but only 4V is Logic OK.
                              1) 1.2V implies that your voltage regulator is bad.

                              2) Normally, the connector from the power to the logic board is 5V DC, not 4V. If it is 4V DC, then that might affect the reading of the voltage regulator above.

                              3) What is the DC voltage that you are reading on the connector between the 2 boards? Please report them for all pins.
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                              Comment


                                #16
                                Re: Half success on AL1716

                                Originally posted by retiredcaps View Post
                                1
                                2) Normally, the connector from the power to the logic board is 5V DC, not 4V. If it is 4V DC, then that might affect the reading of the voltage regulator above.
                                From Power board is 5V, this 4V I send From other power supply. I tested 5V down regulated and all other supply for chip measurement. On 4V is Display aktivation on ACER Logo. Processor and EEPROM is OK.

                                If is Connected Power Board and Logic Board, LED Power still flashes green/red (1sec).
                                On 2 PIN +5V is 5,01Volts
                                On ON/OFF and Brightness PIN I cann not measurement.

                                Backlight have tested separated Power Board, 5V on ON/OFF PIN.

                                Comment


                                  #17
                                  Re: Half success on AL1716

                                  Originally posted by pavedom View Post
                                  My chip U101 AS1117L-18 have only 1,2V.
                                  the Voltage Regulator AS1117L-18 output should be 1.8v no questions. I just replaced that same part in an similar Acer AL1706 Monitor. The appears to be a very week link in this model line.

                                  Comment


                                    #18
                                    Re: Half success on AL1716

                                    Thx, U101 is new and LCD is OK.

                                    Comment

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