Viewsonic VP201b power supply option

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • bioray
    New Member
    • Jul 2011
    • 9

    #1

    Viewsonic VP201b power supply option

    Trying to troubleshoot the power supply on this display. No power out of the switching power supply. Removed all caps and checked and found all in specs. The specs for the power supply are 18vdc 3.3a. I found a 18.5vdc 4.9a external supply. Would this fry the other boards in the display if I were to use it? I have a bench power supply to test the display and it worked great on 18vdc bench power. Just worried about the extra .5v

  • PlainBill
    Badcaps Legend
    • Feb 2009
    • 7034
    • USA

    #2
    Re: Viewsonic VP201b power supply option

    Originally posted by bioray
    Trying to troubleshoot the power supply on this display. No power out of the switching power supply. Removed all caps and checked and found all in specs. The specs for the power supply are 18vdc 3.3a. I found a 18.5vdc 4.9a external supply. Would this fry the other boards in the display if I were to use it? I have a bench power supply to test the display and it worked great on 18vdc bench power. Just worried about the extra .5v

    The extra .5 volts shouldn't kill it, but why not just repair the original supply? They don't get much simpler than that one.

    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

    • bioray
      New Member
      • Jul 2011
      • 9

      #3
      Re: Viewsonic VP201b power supply option

      I would like to repair the supply. When I checked the caps the values were within about 10%. The shockley diodes checked good as well. Kinda of stuck at this point, that's why I was going to rig up an external supply. Any pointers would be appreciated!

      Comment

      • sam_sam_sam
        Badcaps Legend
        • Jul 2011
        • 6030
        • USA

        #4
        Re: Viewsonic VP201b power supply option

        Here is what I would tell you if the power supply is more than 2 years old I would recap this power suply

        I have a lot of switching power supply a litte over two years old and every one of the the caps when BAD POP there tops on them

        When YOU say they are " within about 10% " Is this Over or Under if under REPLACE them they are no good
        Last edited by sam_sam_sam; 07-07-2011, 05:59 PM.

        Comment

        • PlainBill
          Badcaps Legend
          • Feb 2009
          • 7034
          • USA

          #5
          Re: Viewsonic VP201b power supply option

          Originally posted by bioray
          I would like to repair the supply. When I checked the caps the values were within about 10%. The shockley diodes checked good as well. Kinda of stuck at this point, that's why I was going to rig up an external supply. Any pointers would be appreciated!
          I use a two step process for checking power supplies. Step 1 is to check the voltage across the main power supply cap (the 100uF, 450 volt one). It should read 1.4 x your line voltage - 120VAC in yields 165 VDC across the cap.

          If that is correct, I check the voltage across the startup cap. It's a small 22uF to 47uF cap near the power FET. It is often overlooked. If that cap is bad, the power supply won't start. CAREFULLY measuring the voltages on the SMPS controller also will help. And of course, look up the datasheet for the SMPS controller.

          Pictures help us help you.

          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

          • bioray
            New Member
            • Jul 2011
            • 9

            #6
            Re: Viewsonic VP201b power supply option

            Thanks for some direction. I will check those readings tomorrow. A bad cap might just explain the fact that the output voltage slowly ramps up when a/c is applied. Again thanks for the direction! I will report back with what I find.

            Comment

            • PlainBill
              Badcaps Legend
              • Feb 2009
              • 7034
              • USA

              #7
              Re: Viewsonic VP201b power supply option

              Originally posted by bioray
              Thanks for some direction. I will check those readings tomorrow. A bad cap might just explain the fact that the output voltage slowly ramps up when a/c is applied. Again thanks for the direction! I will report back with what I find.
              That might be a bad startup cap or a bad mains filter cap, but what I would check first is the current sense resistor.

              Incidentally, the service manual for this monitor is available 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

              • bioray
                New Member
                • Jul 2011
                • 9

                #8
                Re: Viewsonic VP201b power supply option

                A little help please with locating the components. Current sense resistor, power cap, starter cap.

                Thanks
                Attached Files
                Last edited by bioray; 07-08-2011, 08:48 AM. Reason: added image

                Comment

                • bioray
                  New Member
                  • Jul 2011
                  • 9

                  #9
                  Re: Viewsonic VP201b power supply option

                  The caps measured as follows 150uf =127uf 47uf=30uf 150uf=127uf 680uf=621uf taicon and nichison caps

                  Comment

                  • PlainBill
                    Badcaps Legend
                    • Feb 2009
                    • 7034
                    • USA

                    #10
                    Re: Viewsonic VP201b power supply option

                    Originally posted by bioray
                    A little help please with locating the components. Current sense resistor, power cap, starter cap.

                    Thanks
                    R114=current sense resistor.
                    C101 is the main filter cap.
                    C105 is the startup cap.

                    Some people (I WAS one of them) ignore the small electrolytic caps. C105 and C106 should both be checked and replaced if there is any question about their condition.

                    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

                    • PlainBill
                      Badcaps Legend
                      • Feb 2009
                      • 7034
                      • USA

                      #11
                      Re: Viewsonic VP201b power supply option

                      Originally posted by bioray
                      The caps measured as follows 150uf =127uf 47uf=30uf 150uf=127uf 680uf=621uf taicon and nichison caps
                      Either there is a problem with your meter, or all of those caps are under spec, the 47 uF seriously so.

                      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

                      • bioray
                        New Member
                        • Jul 2011
                        • 9

                        #12
                        Re: Viewsonic VP201b power supply option

                        The resistor checked good @.4ohm rated 0.36ohm. c105 reads 15uf should be 22. and c101 reads 127uf should be 150uf. Checked my meter with some new caps in my shop it seemed to be accurate. Fluke 179 has always worked good for me. C106 is a surface mount, just don't think that i will be able to take that one off to check.. Thanks for the tips. All these caps reading low might just be my problem? maybe? got a reading of 2.5vdc when power supply was loaded and it ramped up to 18vdc when unloaded. Please excuse my A.d.d When a thought comes to mind i have to put it down.

                        Comment

                        • PlainBill
                          Badcaps Legend
                          • Feb 2009
                          • 7034
                          • USA

                          #13
                          Re: Viewsonic VP201b power supply option

                          Originally posted by bioray
                          The resistor checked good @.4ohm rated 0.36ohm. c105 reads 15uf should be 22. and c101 reads 127uf should be 150uf. Checked my meter with some new caps in my shop it seemed to be accurate. Fluke 179 has always worked good for me. C106 is a surface mount, just don't think that i will be able to take that one off to check.. Thanks for the tips. All these caps reading low might just be my problem? maybe? got a reading of 2.5vdc when power supply was loaded and it ramped up to 18vdc when unloaded. Please excuse my A.d.d When a thought comes to mind i have to put it down.
                          I seem to have misread the schematic. If C108 is a small electrolytic cap, check it. Low capacitance on these caps can cause problems.

                          A quick history. We've known for a couple of years that a bad startup cap will prevent the monitor starting. Some time ago a friend gave me a Samsung 17" LCD TV / Monitor that would not power up. The only sign of activity was a clicking sound about every second or two from the speakers. This TV had an external 12V 4.5A power brick, so the first test I performed was to test the output under load. I use an 1157 automobile lamp as a 2 Amp load, and the power supply worked perfectly.

                          After many false leads, I discovered the TV worked perfectly when hooked to a bench supply, so I turned my attention back to the power brick. All the filter caps had an ESR that was slightly high. Ordinarily, that would not be a problem, but the problem was obviously the power brick, so I replaced them, and that didn't help. The next step was to dig out some of the glue and free the startup cap. Replacing that fixed the power supply.

                          Obviously, the startup cap was working well enough to keep the supply working at a light load, but not well enough to keep it working under full load. I've got a few theories of why this was the case, but the experience confirmed my opinion - ALWAYS replace the one or two small caps next to the SMPS controller.

                          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

                          • bioray
                            New Member
                            • Jul 2011
                            • 9

                            #14
                            Re: Viewsonic VP201b power supply option

                            C108 is reading low as well. This display is 5years old after all. I guess all the years of use has taken its toll on the caps.

                            Comment

                            • bioray
                              New Member
                              • Jul 2011
                              • 9

                              #15
                              Re: Viewsonic VP201b power supply option

                              Replaced caps on the power supply. Got correct voltage out. Back lights come on and I get a solid blue screen with no graphics or characters displayed. Reseated ribbon cables to no avail. The monitor worked before repairing the power supply. After repair and reassembly I now get a solid blue screen. Getting aggravated with the display. Any ideas. Has to be logic board.

                              Comment

                              • jsog
                                Badcaps Veteran
                                • Feb 2011
                                • 220

                                #16
                                Re: Viewsonic VP201b power supply option

                                Check the capacitors on the processor board. Also make sure the button cable is connected at both ends.

                                Comment

                                • mcof
                                  New Member
                                  • Mar 2015
                                  • 1
                                  • United States

                                  #17
                                  Re: Viewsonic VP201b power supply option

                                  I know this is an old thread but it's coming up on google and I have a few things to add.

                                  1) The monitor will happily run on the HP 18.5V 3.5A supplies
                                  2) If you crack off the plastic casing it will fit in place of the original power board, barely (see image)

                                  Recapping my board didn't quite do the business so I decided to go this route since used laptop supplies are dirt cheap and work out of the box. Used the back ends of crimp connectors to interface with the C6 power pins and the rest is just solder and heatshrink. Ignore the black connector, should have re-used the original. If anyone else does this remember to strap the earth and connect the hot wire (should be the blue one) through the switch.
                                  Attached Files

                                  Comment

                                  • Folxs
                                    Senior Member
                                    • Nov 2016
                                    • 167
                                    • Poland

                                    #18
                                    Re: Viewsonic VP201b power supply option

                                    Hi, thanks for sharing information, that this is 18V power supply 3.3A - how did You found it?
                                    That info helped me troubleshoot my power supply. (I got sign on it 15V2A so I thought, that it is 15V 2A but it was not!)
                                    In my case that cap 22uF 50V was measuring 2uF so I replacement it and that works just fine.

                                    Comment

                                    Related Topics

                                    Collapse

                                    • Tynan Dill
                                      Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?
                                      by Tynan Dill
                                      I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.

                                      Upon bringing it home and plugging it up, it showed a standby light.

                                      I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.

                                      The screen seems to blackout and stay black, but with a flashlight I can see the display.

                                      With my Playstation 4 connected via HDMI, and running a game I can hear sound.

                                      Assuming...
                                      11-22-2024, 01:46 PM
                                    • sam_sam_sam
                                      Desoldering gun station modified to use a 18 volt @ 20 amp switching power supply
                                      by sam_sam_sam
                                      I have wanting to do this project for quite sometime now and I finally found a switching power supply that will work on this desoldering gun station ZD-915 that the original switching power supply took a shit and just was not worth trying to fix it because this switching power is not quite big enough to handle the heater element and the vacuum pump

                                      One note when I tested the switching power supply and the voltage control board I noticed that this desoldering gun heat up much faster than the original switching power supply which I was really surprised by to the point that I might buy...
                                      03-31-2024, 02:12 PM
                                    • sam_sam_sam
                                      Modification to a ZD-987 desoldering/soldering station using a external switching power supply
                                      by sam_sam_sam
                                      I have been working on this concept for quite some time now with limited success but recently I found a switching power supply that is setup for the voltage that this soldering station needs to operate at however it also needs part of the secondary circuit from the original switching power because you need several voltage rails

                                      I once tried to get a ZD-915 desoldering station to work on a 18 volt battery power supply but unfortunately things did not go well but I did find a work around but I might try this idea again but going at a little differently more about this another time...
                                      07-01-2024, 06:34 AM
                                    • Fagauthier
                                      Viewsonic power supply model #EADP-64BF B Need circuit diagram…
                                      by Fagauthier
                                      I have à defective Viewsonic monitor. I can't find a circuit diagram for it' power supply.
                                      Model #EADP-64BF B
                                      The user manual have all diagram except for the power supply. I would appreciate help to find the circuit diagram, thanks...
                                      07-08-2023, 08:02 PM
                                    • CMCM
                                      Russound CA4 Power Supply Repair
                                      by CMCM
                                      Hello Everybody,

                                      Trying to repair a power supply from a Russound CA4 Multizone Controller (picture attached)

                                      Russound no longer supports it but were kind enough to provide a schematic of the power supply (pdf attached).

                                      The outputs marked 12v and 20v are all measuring only 1v.

                                      The board is clicking, which I think means it is in something called hiccup mode when the flyback transformers switches because of an internal problem or something else on the board Overloading it.

                                      The capacitors physically look clean (no bludgesor leaks) and...
                                      07-03-2025, 01:12 PM
                                    • Loading...
                                    • No more items.
                                    Working...