Benq G2255 doesn't power on - amber power light when plugged in

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Dumah Brazorf
    Senior Member
    • Jun 2013
    • 179
    • Italy

    #181
    Re: Benq G2255 doesn't power on - amber power light when plugged in

    My experience is that i had to change lamps that look good the few seconds they was working but was worn/burned at the ends.
    You can only open that panel, it's not hard but tedious. Changing the cfl desoldering the old and resoldering the new in the manner that fits inside the panel instead is a pain in the arse...
    Last edited by Dumah Brazorf; 01-25-2018, 02:39 PM.

    Comment

    • rddube
      Aspiring Expert
      • Jun 2013
      • 907
      • Canada

      #182
      Re: Benq G2255 doesn't power on - amber power light when plugged in

      Will, I am getting weird results. Still with pin 3 lifted and jumped to pin 2. When CFL's inverted, they come on and turn off after a few seconds. I did the test 3 times, same results.

      Swapped the CFL's, first test they wouldn't come on, so I thought maybe I have to wait a little for the chip to reset. Tried it after a few minutes, wouldn't come on. So I checked my jumper and the AC plug and tried it again, and this time they came on, but out after a few seconds. Waited approx. 2 minutes, they came on and out after 2 seconds. Waited about 5 minutes, this time they came on and stayed on. Turned them off, waited another 2-3 minutes, they came on and stayed on.

      It's as if the problem is intermittent? What should I do now?

      Comment

      • rddube
        Aspiring Expert
        • Jun 2013
        • 907
        • Canada

        #183
        Re: Benq G2255 doesn't power on - amber power light when plugged in

        Originally posted by Dumah Brazorf
        My experience is that i had to change lamps that look good the few seconds they was working but was worn/burned at the ends.
        You can only open that panel, it's not hard but tedious. Changing the cfl desoldering the old and resoldering the new in the manner that fits inside the panel instead is a pain in the arse...
        Hi Dumah,

        Tks for the info. I would really like to avoid having to change the lamps, because I don't have any spares and also, there is a problem on the main board that I haven't tackled yet, trying to get the power board to work. If you look at Budm's previous post, he show a way you can test the board with scrap CFL lamps which is pretty neat. I'll have to see what Will thinks (and Budm) before contemplating changing/testing the lamps.

        Comment

        • will62
          Badcaps Veteran
          • Dec 2016
          • 229
          • usa

          #184
          Re: Benq G2255 doesn't power on - amber power light when plugged in

          Move on to pin 2 lifted.

          Comment

          • rddube
            Aspiring Expert
            • Jun 2013
            • 907
            • Canada

            #185
            Re: Benq G2255 doesn't power on - amber power light when plugged in

            Ok, Will. Just to let you know however, I tried it again after about 10 minutes (pin 3 up) and CFL in original slots, and they came on and 2 seconds they were out. Waited about 45 minutes before coming to see if you had replied, so went to the board to move on to pin 2 lifted. Before dismantling it, tried it again, the came on and stayed on!

            Ok, moving to pin 2 now.

            Comment

            • rddube
              Aspiring Expert
              • Jun 2013
              • 907
              • Canada

              #186
              Re: Benq G2255 doesn't power on - amber power light when plugged in

              Ok, so resoldered pin 3, lifted pin 2, jumpered to pin 3. CLF in original position. First time I flip the power bar switch, I got a quick flash from the CFL's then black. Waited approximately 1 minute, then when turned on they stayed on.

              Swapped the connectors. Exactly the same thing. First time I switched the AC on, got a quick flash from the CFL's then black. Waited approximately 1 minute, turned them on and they stayed on.

              Comment

              • will62
                Badcaps Veteran
                • Dec 2016
                • 229
                • usa

                #187
                Re: Benq G2255 doesn't power on - amber power light when plugged in

                Ok, solder pins back down. Get me that resistance to ground for each pin (2,3).
                Let's try extending the time the chip gives before faulting. Remove C803. Measure it's value. Try to find a replacement on another board with ~3 times the value. Remember, if you have to, you can parallel 2 and add their values.

                example: If you measure it as 820nf, try to find a replacement in the range of 2.5uf.

                After changing cap(s), turn on with and without pin 5 jumped.

                Comment

                • rddube
                  Aspiring Expert
                  • Jun 2013
                  • 907
                  • Canada

                  #188
                  Re: Benq G2255 doesn't power on - amber power light when plugged in

                  Ok, resoldered evrything and measure pin 2 and 3 to ground.

                  Pin 2: 2.403Kohms
                  Pin 3: 2.406Kohms

                  Now did partially the other operation to remove C803 and checked the value with my Fluke and transistor tester.

                  With the Fluke I get: 1.027uf
                  With the transistor tester I get 1030nf

                  I guess this is the same thing. As a replacement I found a 2.15uf and a 6.14uf...the 2.15uf is 2X the value and the 6.14uf is 6 times the value. Which one should I use Will?
                  Last edited by rddube; 01-25-2018, 08:55 PM.

                  Comment

                  • rddube
                    Aspiring Expert
                    • Jun 2013
                    • 907
                    • Canada

                    #189
                    Re: Benq G2255 doesn't power on - amber power light when plugged in

                    Ok Will, found one that was 2.33uf, so I tried it. Now the lamps turn on for about 5 seconds before going out. Jumpered on C803, they stay on nice and bright.

                    Comment

                    • will62
                      Badcaps Veteran
                      • Dec 2016
                      • 229
                      • usa

                      #190
                      Re: Benq G2255 doesn't power on - amber power light when plugged in

                      OK. We doubled the delay, and it still failed. Do you have any 1N4148 diodes? Would need 2. If not, you're going to need to pull that B6 diode off the other board and check it. Is it a common anode dual? Should test just like the diode D801. If so, go ahead and try it. It's under valued, so it may fail, but we need to rule out the diode.
                      Last edited by will62; 01-25-2018, 09:56 PM.

                      Comment

                      • rddube
                        Aspiring Expert
                        • Jun 2013
                        • 907
                        • Canada

                        #191
                        Re: Benq G2255 doesn't power on - amber power light when plugged in

                        Oops, Will I think you lost me there. I googled 1n4148 diode and they are those little orange diodes ...i have lots on scrap boards. We need 2, so where would we put them? I can't seen to find the B6 diode? Please elaborate or guide me....I have lots of all kinds of standard diodes like the black ones in the photo.
                        Attached Files
                        Last edited by rddube; 01-25-2018, 10:13 PM.

                        Comment

                        • will62
                          Badcaps Veteran
                          • Dec 2016
                          • 229
                          • usa

                          #192
                          Re: Benq G2255 doesn't power on - amber power light when plugged in

                          We need an ultra fast switching diode. Regulars won't work. I believe the B6 was one of the ones you listed the other day. If it's what I think it is, it's the only one that is close to what we need for D801. I know you checked D801, but we need to rule it out.

                          (added explanation)
                          The way D801 is set in the circuit, it should be clipping most of the negative portion of the wave (see pic 1). D801 is a dual, both signals (pin 2,3) are going through it. That's why I asked you if the negative swings on pin 2 were a fluke, or happening all the time. The chip has an open lamp detector and it is triggered by either LI1(p2) or LI2(p3) pulling down an internal signal (see pic 2). I hope that explains why I'm concerned about the negative swings on the signals.
                          Attached Files
                          Last edited by will62; 01-25-2018, 11:08 PM.

                          Comment

                          • rddube
                            Aspiring Expert
                            • Jun 2013
                            • 907
                            • Canada

                            #193
                            Re: Benq G2255 doesn't power on - amber power light when plugged in

                            Hi Will,

                            Ok, thank you so much for clearing that up. While reading your post, I realized that I had ordered some switching diodes from China a few years ago while trying to fix an Asus motherboard. So I searched my "motherboard" junk box and found some Bat54cw-7, L2n7002ltig, hsb2838, hsm2838c and some other marked 3IA that I can't remember the technical number, but I believe the bat54cw-7 could maybe do the job?

                            Comment

                            • will62
                              Badcaps Veteran
                              • Dec 2016
                              • 229
                              • usa

                              #194
                              Re: Benq G2255 doesn't power on - amber power light when plugged in

                              I was thinking that the one marked B6 was a BAT54. The BAT54 comes in 4 flavors. The "cw" is a single diode package. I believe the B6 is dual common anode, which is what we need. It is under-valued and might blow at power on, but I was wanting to check it. If you can't find the B6, I see Frankenstein II coming on. The HSB2838 has perfect ratings, but is a dual common cathode. Can you figure out how to use 2 of those with pieces of a resistor leg to make a dual common anode that will solder to D801's pad?

                              Comment

                              • rddube
                                Aspiring Expert
                                • Jun 2013
                                • 907
                                • Canada

                                #195
                                Re: Benq G2255 doesn't power on - amber power light when plugged in

                                In the meantime I took some more readings with the oscilloscope, this time I used my needle probes and was at the pin itself. Here they are.

                                For Frankentein 2, is this what you had in mind?

                                Will wait for your comments on the oscilloscope readings before building Frankie!
                                Attached Files

                                Comment

                                • rddube
                                  Aspiring Expert
                                  • Jun 2013
                                  • 907
                                  • Canada

                                  #196
                                  Re: Benq G2255 doesn't power on - amber power light when plugged in

                                  Ok, so I probed between R837,R839 and then between R841,R843 and am getting pretty much the same waves. If you want I can upload pictures.

                                  Comment

                                  • will62
                                    Badcaps Veteran
                                    • Dec 2016
                                    • 229
                                    • usa

                                    #197
                                    Re: Benq G2255 doesn't power on - amber power light when plugged in

                                    That's exactly what I had in mind for Frankie II, but hold off, you may not need it. Your pics of waves taken today, show that the diode is doing what I expected. Compare today's pic Vmins with an older pic that had me concerned about the diode. I wrote on the screen what the Vmins were on the older pic. Also Note the difference in Vpp. Today, you're barely clearing 1V, whereas before you had ~12V. Are you using different multiplier settings on the scope? If you are actually near 1V, that Vpp is right at the threshold for open lamp fault. (from 1009 datasheet: LI1 and LI2 Inputs...-5.8V to +5.8V, typical circuit on datasheet not using clipping diode)

                                    Try probing at the voltage divider as mentioned in an earlier post. No need for pics, just give me the voltage readings on the scope.

                                    Added: Voltage readings at dividers?
                                    Attached Files
                                    Last edited by will62; 01-26-2018, 01:06 PM.

                                    Comment

                                    • rddube
                                      Aspiring Expert
                                      • Jun 2013
                                      • 907
                                      • Canada

                                      #198
                                      Re: Benq G2255 doesn't power on - amber power light when plugged in

                                      The pics today are on 2 voltage scales (says in the lower left of the screen). Also, notice that the voltage readings are in white font...when I was probing between r837, r839 and r841, r843, the voltage readings were in red and didn't seem to register? Might be my scope, this thing is not precise.

                                      Also today's pics were taken at the chip pin, whereas the other pics were taken at the output of the diode which was my closest point near a component.

                                      Just to make sure I am doing it right, when you say to probe between r837 and r 839, I suppose you mean the left side of R839 or the left side of r837?

                                      Comment

                                      • will62
                                        Badcaps Veteran
                                        • Dec 2016
                                        • 229
                                        • usa

                                        #199
                                        Re: Benq G2255 doesn't power on - amber power light when plugged in

                                        Left side, closest to diode, of R837 and R841. If you do not get a sine wave of ~12V peak to peak, try lifting top tab of diode.


                                        On the scope:
                                        OK, your multiplier and volts/div combine on screen. My multi is on the probe. You're still getting a low Vpp.
                                        Yeah, I realize that you are using a 200kHz scope to look at 70kHz waves. Enough bandwidth to see that a signal
                                        is there, but not enough to zero in on anything.
                                        Last edited by will62; 01-26-2018, 01:39 PM.

                                        Comment

                                        • rddube
                                          Aspiring Expert
                                          • Jun 2013
                                          • 907
                                          • Canada

                                          #200
                                          Re: Benq G2255 doesn't power on - amber power light when plugged in

                                          At the setting of 1V X 1 multiplier, I get 1.45V vpp for R837 and 1.65V vpp for R841. I'll try now with the diode tab lifted and report back in a few minutes.

                                          Comment

                                          Related Topics

                                          Collapse

                                          • huzo
                                            HP 470 G5 blinking amber light no power
                                            by huzo
                                            The board is daox8cmb6eo and i can't find no boardview or schematics on the forum or anywhere...

                                            So i plug in the charger, amber light starts blinking ,there is 3.3V and 5V present, and 2.4V on the power button,board doesn't turn on, no shorts...
                                            I've tried flashing the bios...

                                            interesting thing is the battery was around 7,8V, and it's 11.1V battery, the mosfet near the battery is open, but not charging,i desoldered it,tested it and it's fine ,but the amber light kept going on the charger so i charged the battery with power supply and got it to about 10.5V...
                                            06-08-2023, 04:08 PM
                                          • PantherDave
                                            Microsoft Surface Pro (5th gen) model 1796 - no power
                                            by PantherDave
                                            Hi all!

                                            I'm trying to troubleshoot a Microsoft Surface Pro (5th gen) model 1796 that won't power on. Motherboard model is M1007506-015. My priority is retrieving data, but the SSD is integrated so it looks like if I can't repair it it'll need to go to a data recovery company. I've done a little basic board repair before, but nothing this advanced until now. So please forgive my ignorance in advance. 😅

                                            I found the boardview for this laptop in the forums here, and am able to open it on my PC with FlexBV.
                                            https://www.badcaps.net/forum/troubl...-hardware-devi...
                                            05-29-2024, 02:01 PM
                                          • zwect
                                            Dell Latitude 5420 / GDF40 LA-K491P REV 3.0 / Amber / Orange light when power button is pressed
                                            by zwect
                                            I have this Dell Latitude 5420 with ST: CMF62F3, board GDF40 LA-K491P REV 3.0 that does not power on, i already searched for some clues about this problem that happens on mine but no BIOS i downloaded and flashed did anything.
                                            Only when the power brick is connected, when pressing the power button an amber light lights up at the front and slight decreases its brightness, the RAM and the CPU seem to heat up if the laptop is left connected but nothing else, other than USB devices getting powered.
                                            Here is the original BIOS dump from the 25R256JVEN chip.
                                            09-11-2024, 05:54 PM
                                          • ipatch
                                            troubleshooting microsoft surface pro 4 no power no led charge light
                                            by ipatch
                                            hello, �� i have been sitting on some microsoft surface pro 4 tablets for a while now. i was originally tasked with replacing the battery in one of the tablets, and ended breaking the screen and logic board in the process. decided to buy another tablet with the same specs. got that screen off successfully of the second tablet. the logic board appeared good, but i guess i shorted something out in the installation process of the logic which i've read is a common issue if there is no barrier between the logic board and battery pins. all that said, i ate costs of the repair and have...
                                            10-05-2023, 11:59 AM
                                          • russpall
                                            LG 39ln540v - red light flashes twice, no power to LED driver?
                                            by russpall
                                            Hi there,

                                            I've got a 39" LG 39LN540V that's just spontaneously stopped working! The symptoms are - when I plug it in, the red light will flash on twice, then go out, there's no visible picture, and I couldn't see anything using a torch on the panel either. If I press the power button (either remote or on TV), the red light comes on continuously. If I press power again, the red light flashes twice.

                                            The TV is using a power board EAX64905301. I've attached a diagram of the power output, I've tested the voltages with a multimeter and I'm getting the following:
                                            ...
                                            08-27-2024, 01:07 PM
                                          • Loading...
                                          • No more items.
                                          Working...