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The PVM-2730QM thread (H-STAT issue, colour bleed, convergence and more!)

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Dead monitor? something dosent look right on the screen? monitor repair questions here.

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  • Originally posted by Zebidee View Post
    I'm not sure I can see the grey, but carbon on terminals could indicate an issue or create poor connection or both.

    I notice your neckboard has a bunch of those solid carbon resistors. They include R715,717,719,722-729. Sony liked using them on neckboards in particular. Refer pp 70 and 88,89 of the service manual buttersoft linked. In the parts list Sony calls them "SOLID", and they look a bit like a bumblebee capacitor, colour-striped cylinder.

    These guys can deteriorate over time, bit like electrolytic capacitors, especially when under high voltage loads. Trouble is, they don't just blow open and stop working. Their values start to slide and vary over time (generally higher resistance). As they degrade they can drag other components with them. Several of us have already replaced some of them in our PVMs with higher-rated (Wattage) metal oxide resistors.

    This one circled here is R724 (220k 1/2W) I think, which according to the schematic grounds the H2 line to G1. Worth checking it with a multimeter to see if the value has changed significantly. May as well check the others and all the electrolytic capacitors while you're in there.
    Click image for larger version

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    Hello,
    first of all thank you very much for your help!

    So I desoldered some solid carbon resistors and the 3 electrolytic capacitors and did measures:
    Resistances:
    R722 680K -> 695K ; R723 100K -> 90,7K ; R724 220K -> 232,5K ; R725 100K -> 91,5K
    R715 1K -> 0,9K ; R717 1K -> 0,868K ; R719 -> 0,880K

    Capacitors :
    C705 100MF ->103 ; C726 22MF -> 23,3 ; C733 10MF -> 10,2

    Do you think something is out of range?
    Everything is back, and problem still there.. Knocking the screen/Canon, and the image is perfect..
    Is it possible to have a short in the socket itself? we can open it?
    What I still not get, it's why when the problem is there, the H1/H2 is between 140-170V.. and at 0 when the problem is not there. When this voltage should come? to heat at start?


    Comment


    • Values within 10% generally ok, even up to 20% maybe.

      Some tips:
      - You can mostly just measure the resistors in-circuit. I know not always 100% accurate but usually good enough to pick up when one of these resistors is failing (because value will be much too high).
      - You can also mostly avoid removing the electrolytics to test if you have an ESR (Equivalent Series Resistance) meter. When electro caps go bad their ESR almost always starts spiking upwards, so it is a good way to root out the bad apples without having to go full recap. No need to remove the caps from PCB to test with ESR meter.

      I'm a bit confused and don't quite understand is how heater voltage could be ~170v - I thought they mostly ran at 6.3v, but I haven't much experience with. Feel like I'm missing something. Is there a short somewhere?

      Check C707 (blue disc cap, 680p) as well, though these guys rarely fail.

      On schematic there isn't much anything complicated between H1/H2 and the flyback. Triple check all your connections including GND at CRT socket and at connector CN702 (is a pin loose?). Check to see if you get 180v at pin 2. If there is no connection issue and nothing else is faulty it may be either a problem with the flyback or with the filament in the CRT itself.

      Let me know if you want to buy an ESR meter as I have a few of the original Dick Smith ESR meters (in kit form). I also still have a few of the Dick Smith flyback (LOPT) testers as well. Both useful kit if you want to do CRT repair.

      Comment


      • I didn't realise the newer model still had solid-carbons. They tend to fail high, don't they? But it's definitely a place to start.

        Comment


        • Hey,
          All the components measured are quite ok..
          I really suspect the short in the canon or the socket.. I think this monitor will be for piece

          Comment


          • Maybe it is just a poor pin connection at the socket? It can happen if the female ends get pushed too wide.

            To see if there if heater filament looks good, run monitor in dark to see heater glow.

            Check that 180v supply to pin 2, see if it is OK. If not OK can trace back to source, maybe something there causing hassles.

            Sad if you have to give it up for parts :'( These old PVMs are starting to be worth real $$.

            Comment


            • Originally posted by Zebidee View Post
              Maybe it is just a poor pin connection at the socket? It can happen if the female ends get pushed too wide.

              To see if there if heater filament looks good, run monitor in dark to see heater glow.

              Check that 180v supply to pin 2, see if it is OK. If not OK can trace back to source, maybe something there causing hassles.

              Sad if you have to give it up for parts :'( These old PVMs are starting to be worth real $$.
              180V are well there,
              I truly think that I have a short of a color with heater..
              The traces are green and taping the tube I have some green interferences.. so short with green maybe!

              I think to test it, it's very easy to confirm or exclude by lifting one side of the resistor coupled to the green cathode. If green remains it means the cathode is shorted to the heater and only a rejuvenator may fix it I think?. If green goes completely there is some fault (e.g. shorted video amp transistor) in the green circuit or something..

              I will give a try because when the image is ok, the image is just amazing!!!

              Comment


              • Originally posted by Playa21 View Post
                I think to test it, it's very easy to confirm or exclude by lifting one side of the resistor coupled to the green cathode. If green remains it means the cathode is shorted to the heater and only a rejuvenator may fix it I think?. If green goes completely there is some fault (e.g. shorted video amp transistor) in the green circuit or something..
                I think this would have the opposite effect, cause screen to flood with the colour you disconnect or short to ground.

                Comment


                • Originally posted by Zebidee View Post

                  I think this would have the opposite effect, cause screen to flood with the colour you disconnect or short to ground.
                  Hey,
                  I followed the advice of someone on another forum on internet..
                  Putting the screen face down, taping left and right on the canon with a soft tool to try to remove the impurity stuck in the canon..
                  2h after power on, not seen the problem so far.. Let's cross the finger I get rid of it

                  Edit: The problem is not there anymore.. sometimes a 'click' is coming on the canon... near the socket..
                  There is definitively a short inside.. and it happens sometimes and the image is just vibrating..
                  Last edited by Playa21; 17 February 2021, 03:48 AM.

                  Comment


                  • IT LIVES!

                    That's great news! Clever solution to something I thought you'd be stuck with. Well done 😎

                    Comment


                    • Yeah, that is clever. Have to put that one in the bag of tricks for sure.

                      Comment


                      • yep!
                        Thats a good news.. I think to remove completely the intermittent small 'shock' we can have in the canon, only a rejuvinator car help..
                        Thanks for your help, we learn a lot by touching

                        Comment


                        • Hi Guys,

                          This monitor was like this when purchased. I’ve had suggestions on a simple pot adjustment like pin amp/pin cushion or any pots that have amp.

                          I’ve never opened a monitor so what do you guys think?

                          Thanks

                          Comment


                          • Welcome to AA, and thanks for posting up in here Opening a PVM-2730 isn't too hard. When you look at the back, it has ten #2 phillips screws you need to undo to slide the case off. One is just under the dials on the back at the top, one is just above the inputs near the bottom (both in the middle of the set). The other eight are in groups of two at each corner just around where the solid housing begins and the handles start. See the red dots on the pic below. Once undone, the whole section with the handles will slide out backwards. It might be stuck, so wiggle it a bit first, firmly if required. The remaining CRT section has all the weight but less of the stability, so consider doing this whole process on the floor. To get the case back on you may need to rock the bezel-section very slightly forward so the lower board clears the rear case.

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                            Geometry adjustments need to be made with the set running, of course. You won't need to stick your hands into the set itself for any of the adjustments described in this post, everything can be reached from the outside. There are still live voltages exposed, so don't lean on the set, don't let things fall on it, and don't touch things you don't need to. And remember that parts of a CRT can be dangerous for weeks or years after you turn the power off.

                            Once the case is off, the D3 board is the one you want to be looking at for the pincushion. Be aware the set will work at both 50Hz and 60Hz refresh rates (whether PAL/NTSC or RGB). There are semi-separate controls for both, and you need to calibrate both if you want to use both. I say semi-separate as the controls for one mode do affect the other. Take a photo of the positions of the pots first - they have little yellow heads on them, most of the time, which often fall off but don't be concerned. You can press them back on when the set is off if you want to. Before making adjustments, show one mode first, then the other. Then set one mode, then the other, and then go back to the first, and swapping until you get things as close to perfect as you can for your use case(s). Sadly these adjustments are not covered in the service manual, but they are labelled (like PIN50 or PIN60) and twiddling the pots is pretty easy.

                            You may actually want to set the screen size and position first. This is done on the D board, from the back (You're looking at the back when it's in it's normal position). The adjustments are made through the little marked holes with a thin flat-end screwdriver like a jeweler's screwdriver. Something with a plastic handle is going to be best. There are dangerous voltages elsewhere on the back of the D board, so keep your hands to yourself. The adjustments you want are in Section 4, Circuit Adjustments (page 19) of the service manual. From memory that shows a front view, and you're looking from the back. Take a good look while everything is powered off, stick a screwdriver in and feel the pot move, etc. Then power up and go for it. Size may change slightly between 50/60Hz too, but it shouldn't be a massive jump.

                            https://archive.org/details/sony_PVM...e/n17/mode/2up

                            That should cover the worst of the issue in your picture. I don't think that green line on the side is anything to worry about by itself, and definitely not if it ends up offscreen. If the geometry adjustments don't cover the problem we'll take things from there, if possible

                            I do notice some dynamic (i.e. corner) convergence issues in those photos, but I've only seen one of these sets that didn't have that. It can sometimes be minimised by the adjustments on the D2 board, but that's a bit more complicated. I'm happy to post up separately about that, but if you're going to touch that, make sure to take a clear photo of the pots first, before you play with things.
                            Last edited by buttersoft; 9 June 2021, 04:43 PM.

                            Comment


                            • Hi Everybody,
                              First post on the forum so I wanted to start by thanking you for all the good information documented in this thread and the willingness to help anybody looking for help.

                              I have been working on fine tunning the geometry of my monitor and I have been steering at this damn grid for too long now that I can't objectively look at it anymore, hence my request to seek some feedback from the community here.
                              The only obvious flaw I can see is with the top pin but using the corresponding pot does not really help.
                              Should I just stop looking at this grid and enjoy some content or does somebody have some trick up his sleeve to further improve the situation ?
                              Click image for larger version

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                              Comment


                              • Welcome to AA

                                TBH these sets are at minimum about 25 years old. From experience with about seven or eight different units i can tell you yours is in excellent condition from that screenshot. It's not possible to get any CRT completely perfect, and the larger and older it is, the harder it generally gets. I would say you won't be able to do better than that geometry. Definitely time to enjoy what you've got


                                Originally posted by Kirua View Post
                                Hi Everybody,
                                First post on the forum so I wanted to start by thanking you for all the good information documented in this thread and the willingness to help anybody looking for help.

                                I have been working on fine tunning the geometry of my monitor and I have been steering at this damn grid for too long now that I can't objectively look at it anymore, hence my request to seek some feedback from the community here.
                                The only obvious flaw I can see is with the top pin but using the corresponding pot does not really help.
                                Should I just stop looking at this grid and enjoy some content or does somebody have some trick up his sleeve to further improve the situation ?

                                ducvo did you open up yours and take a look at things?

                                Comment

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