Announcement

Collapse
No announcement yet.

I need help with my friend Sony GDM-FW900 24” CRT

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    I need help with my friend Sony GDM-FW900 24” CRT

    Hello, Badcaps is my last resort. I am the first owner of the monitor. I reached almost every repair store in my area, but no one even wanted to hear about troubleshooting an old CRT monitor. At this point, I have been trying to figure it out by myself, but I have no idea where to start or look for.

    I wish to know how to think and locate a failing component. I will put all my efforts to learn and contribute.
    1. It started with a bright and greenish picture upon starting a cold monitor.
    2. About 2 years ago, only on the cold boot, the screen started to occasionally flash with a green picture with retrace lines.
    3. About one year ago, when the screen was flashing on a high resolution I had to switch the input to only the OSD menu because in another case the screen would turn off and the diode would start to blink orange.
    4. At this point, I started to turn on the screen with 640x480 resolution to the moment when he will warm up.
    5. Always after the power station was turning on and off electricity, the issue started to progress. Basically, the electricity was cut off from the monitor a few times in a row in a very short period of time.
    6. After a few episodes like that, the screen started flashing red instead of green.
    7. After a few months, it was green and red in a similar proportion. The monitor had to be warmed up by switching INPUT 1/2 to calm him down.
    8. At this time I have decided to keep him turned on all the time. He was working from one electricity shutdown to another.
    9. After another episode with electricity, I wasn't able to power him on. I need to press the power button on and off for 20 minutes to finally succeed.
    10. At this point, the only way to power him on was by pressing power on and off and changing the inputs from the front panel. He needs to stabilize and I won't do anything he will turn himself off like in this video
      https://youtu.be/DD-MtnyMbK4?t=695
    11. The last few times I was able to power him after heating his back with a hairdryer. When he was turning on he wasn't flashing red or green. He was warmed up.
    12. At this point, I have stopped trying to power him on. There is a big chance that I would be able to turn him on but in the long run, it's pointless.


    I have to fix my friend.

    From the observations.
    • When the monitor will luckily turn on there are absolutely no issues as long as he is displaying the picture. When the monitor will lose power or will go to standby mode it is not working and cannot be turned on.
    • When the monitor will somehow turn on it is flashing green, red, or both. It depends on the room temperature.
    • If he receives a high-resolution picture from a graphic card (higher voltage needed to operate) he is flashing green and red and goes to the standby mode and cannot be turned on again. He cannot stabilize
    • It was required to keep him on 640x480 dpi until he will warm up
    • If the back of the monitor was preheated with a hairdryer from the sides and turned on there is no green and red flickering and can instantly operate on higher resolutions with no issues. If he will luckily turn it on.
    • When he cannot be turned on and there is no graphic card connected to the monitor the led is green and goes to standby mode. There is no OSD menu displayed at all or green INPUT subtitles on the screen. https://youtu.be/8qnAlrleKpY
    • If he has a graphic card (first video input 1) connected, the monitor after a few seconds starts blinking orange - no light - orange no light infinitely. In the video below I am switching from INPUT 2 (no source) to INPUT 1 (VGA source). For BNC sources the same situation. There is no OSD menu displayed at all or green INPUT subtitles on the screen. https://youtu.be/LAPU1j8QsXE


    - I have dissembled him and could not find any burned, discolored, odd electronic elements.
    - I couldn't spot any cold joints with a magnifying glass.
    - I measured the output G board voltages upon turning on the monitor (green diode).

    CN651
    7V = 7V

    CN650
    STB5V = 5V
    1W5V = 5V
    ECO SW = 5V -> po chwili 3.5V
    HTR SW = 4.9V
    DGUSSW = 4.8V -> 0V
    PWR SW = 5V

    CN652
    STBY5V = 5V
    1W5V = 5V
    +80V = ~15V for 1/2s -> 0V
    +220V = ~90V-200V for 1/2s -> 0V
    +12V = ~3.43V for 1/2s -> 0.04V
    HEATER = 5V

    CN653
    +15V = ~1.36V for 1/2s -> 0.02V
    -15V = ~2.43V for 1/2s -> 0.02V
    +80V = ~3.8V for 1/2s -> 0V

    CN653
    H CENT H = ~4.3V for 1/2s -> 0V
    H CENT N = ~6.3V for 1/2s -> 0V
    H CENT L = ~7.2V for 1/2s -> 0V
    +220V = ~15V for 1/2s -> 0V

    - I have also measured the input on pins 1 to 9 on IC620 MCZ3001D SW REG CONTROL. They are not correct according to the Service Manual. I have voltages on GND and 0. The complete measurements in my playlist https://www.youtube.com/playlist?lis...rUeEXE58CKJpQU

    First video from the playlist https://youtu.be/Bfiso9O2bV4

    At this point, I don't know where should I look for a failing component and how to proceed. If someone has an idea what should I check next and how it suppose to behave I would be grateful for any help. Please, I don't wanna hurt my friend, and it is hard for me to proceed on my own.
    Attached Files
    Last edited by matthewmcconaughey; 05-16-2023, 03:21 PM.

    #2
    Re: I need help with my friend Sony GDM-FW900 24” CRT

    try blowing warm air at different areas to see where the problem is .then check capacitors in that area also check solder joints .

    Comment


      #3
      Re: I need help with my friend Sony GDM-FW900 24” CRT

      I believe it's multiple failing parts here , starting the G board , and not ending by the big capacitor , as well as most of the capacitors .
      The flyback could be also at his life end limits .
      I don;t think its wise to waste money on an old CRT .

      Comment


        #4
        Re: I need help with my friend Sony GDM-FW900 24” CRT

        It is probably bad capacitor and capacitors.
        You should find point where the voltage measure is coresponding to flickering screen or so. Start with some connector on power supply.
        On crt it is a bunch of wires everywhere, high voltage, so be extremly carefull what you touch. Basicaly one method is to cooling down or heat up a specific component (maybe on long plastic/wooden stick), and in same time looking if this applying has some connection to flicker get better or worse. Be patient, not to forward too fast, there is need some time to change internal temperature of components.

        Here is example with ice
        https://www.youtube.com/watch?v=aPAeZWeJ-nw

        If you have a ESR 100KHz meter and a good luck, maybe can spot a bad caps in offline state, but I dont think this is reliabe to do...

        Comment


          #5
          Re: I need help with my friend Sony GDM-FW900 24” CRT

          The issue does sound like bad caps, but could also be something with the firmware bugging up.

          My suggestion is to first re-seat all of the connectors, including the neck board on the back of the tube. Do this at least a few times to clean any possible corrosion or bad contact.

          If the above doesn't seem to make a difference, then my next suggestion is to make sure the PSU is outputting good power. Measuring voltages does not always reveal issues. So probably best to get one of those cheap transistor testers / ESR meters and check all of the caps on the G board, one by one, and NOT in circuit (remove / desolder cap, then test on meter.) Start at the power input side and work your way towards the secondary side. Pay particular attention to small caps, as those tend to dry out and fail without any visible signs. At this point, these monitors are already approaching or over 20 years old... so some of the small caps (particularly those in hot areas or near heatsinks) could be drying up.

          As long as you don't see blue light and hear a "screeching" noise coming from the CRT monitor, your tube should be good... and that's really the most important thing. I have two of these, one with a bad tube, but otherwise all other parts working (at least last I checked around 10 years ago ) and one still working.

          Originally posted by jiroy View Post
          The flyback could be also at his life end limits .
          Could be... but not too likely. I say this, because if the flyback was bad, then heat should not really impact whether the monitor works or not, and that's seems to be mostly the case with the O/Ps. What the O/P really should have done is correct the issue right away instead of running the monitor with the issue, which I imagine could have led to other issues. On that note, I do agree with you - O/P might have several issues with the monitor at this point, but we can go at it one by one.

          Originally posted by jiroy View Post
          I don;t think its wise to waste money on an old CRT .
          Actually, it is.
          At least here in the US / North America and many parts of central and "Western" Europe, there's been an uptick in interest in vintage / old PCs in the last 5+ years. If you follow Vogons.org, you can clearly see how much the "retro PC" community has grown. Some people use these old CRTs just with their retro PCs. Others (like myself) still use them for modern-day gaming, because they're still pretty good for that (no blurring when the image moves, unlike LCDs, even though LCD monitors have improved a lot in the last decade+.)

          In the case of the GDM-FW900, it's a 24" widescreen CRT monitor, so it's a rather rare item and can fetch up to a few thousand $$ in working condition today. So these are definitely worthwhile saving.

          Now the more regular "square" CRT monitors may not be so worthwhile... though even these are starting to get somewhat worthwhile, due to getting rare and hard to find. A 21" CRT can (and often does) go out for $100+ in working condition on eBay (and I'm talking about sold prices, not just obscure listings.) The smaller (19" and 17") usually won't fetch these kind of prices... but not always. Sometimes, people buy even these if they are close by and local pickup is possible (it's really the shipping that makes a lot of people not want to buy them, because they tend to be both bulky and heavy to ship.)

          That said, if your country hasn't "caught onto" this retro PC trend yet, better snatch up some CRT monitors now if/when they are going out for free. Sometime down the road, they might become more valuable even in your part of the world. It's the same with old analog audio and video gear too.
          Last edited by momaka; 05-18-2023, 01:29 PM.

          Comment


            #6
            Re: I need help with my friend Sony GDM-FW900 24” CRT

            Originally posted by momaka View Post
            The issue does sound like bad caps, but could also be something with the firmware bugging up.

            My suggestion is to first re-seat all of the connectors, including the neck board on the back of the tube. Do this at least a few times to clean any possible corrosion or bad contact.

            If the above doesn't seem to make a difference, then my next suggestion is to make sure the PSU is outputting good power. Measuring voltages does not always reveal issues. So probably best to get one of those cheap transistor testers / ESR meters and check all of the caps on the G board, one by one, and NOT in circuit (remove / desolder cap, then test on meter.) Start at the power input side and work your way towards the secondary side. Pay particular attention to small caps, as those tend to dry out and fail without any visible signs. At this point, these monitors are already approaching or over 20 years old... so some of the small caps (particularly those in hot areas or near heatsinks) could be drying up.

            As long as you don't see blue light and hear a "screeching" noise coming from the CRT monitor, your tube should be good... and that's really the most important thing. I have two of these, one with a bad tube, but otherwise all other parts working (at least last I checked around 10 years ago ) and one still working.


            Could be... but not too likely. I say this, because if the flyback was bad, then heat should not really impact whether the monitor works or not, and that's seems to be mostly the case with the O/Ps. What the O/P really should have done is correct the issue right away instead of running the monitor with the issue, which I imagine could have led to other issues. On that note, I do agree with you - O/P might have several issues with the monitor at this point, but we can go at it one by one.


            Actually, it is.
            At least here in the US / North America and many parts of central and "Western" Europe, there's been an uptick in interest in vintage / old PCs in the last 5+ years. If you follow Vogons.org, you can clearly see how much the "retro PC" community has grown. Some people use these old CRTs just with their retro PCs. Others (like myself) still use them for modern-day gaming, because they're still pretty good for that (no blurring when the image moves, unlike LCDs, even though LCD monitors have improved a lot in the last decade+.)

            In the case of the GDM-FW900, it's a 24" widescreen CRT monitor, so it's a rather rare item and can fetch up to a few thousand $$ in working condition today. So these are definitely worthwhile saving.

            Now the more regular "square" CRT monitors may not be so worthwhile... though even these are starting to get somewhat worthwhile, due to getting rare and hard to find. A 21" CRT can (and often does) go out for $100+ in working condition on eBay (and I'm talking about sold prices, not just obscure listings.) The smaller (19" and 17") usually won't fetch these kind of prices... but not always. Sometimes, people buy even these if they are close by and local pickup is possible (it's really the shipping that makes a lot of people not want to buy them, because they tend to be both bulky and heavy to ship.)

            That said, if your country hasn't "caught onto" this retro PC trend yet, better snatch up some CRT monitors now if/when they are going out for free. Sometime down the road, they might become more valuable even in your part of the world. It's the same with old analog audio and video gear too.
            About firmware , yes Momaka , that's possible too , and would cost additional prices to pay . The worst scenario if the IC was damaged
            Sony , at least in my country , offer little support , if any , and refuse to even discuss a repair ..

            On flyback , his first two lines made me think directly of it , because a bad flyback can behave showing brightness at start , and he said , other than the G board problems , he's seeing retraces . If I understood what he means correctly , it's another symptom of flyback deterioration , and next , I read that the mponitor would shut off repeatedly , but to be fair , he didn't say if the sound stays on or off to indicate more . Sometimes also , it could be the brightness button in the flyback and the result is a too bright picture . there , anyway , he can try rotating the control back and forth a few times to clean its contacts . Additionally , sometimes , the flyback , other than delivering high voltage , it may also carry low voltages for some sections , making the same symptoms he's talking about , and which is , apparantely not constant at all .


            On "if your country hasn't "caught onto" this retro PC trend yet" ..

            1) - Actually Momaka , here we caught the absolute reverse , lol ... They're dumping old computers , and it's a standard here to consider , even a 5-10 years old computer and similar , something that should be thrown out .
            Each week or so , I got someone contacting me , in case I can get him rid of his company leftovers . The same goes for tvs and even washing machines ...

            2) - In case he isn't an old repairer , and with huge backup of components , I don't think it's worth the time , price and trouble .
            That's said , what's 100$ for antics ? , it's nothing .. I was offered for my inherited from Granma Singer sewing machine 1500$ .. That's antics ! ..lol .
            If we wanna speak antics , Momaka , Someone should aim for first build and models , like Telefunken in TVs .
            Last edited by jiroy; 05-18-2023, 03:23 PM.

            Comment


              #7
              Re: I need help with my friend Sony GDM-FW900 24” CRT

              look at the neckboard, if there is a 24 or 28pin chip handling the RGB switching/drive then check everything related.
              and most of all with crt monitors - check for cracked solder joints on connectors and heavy components.

              btw, with regard to the line output transformer, it wont do that, it's fine.
              and the tube is probably fine - when those narrow-neck widescreen tubes fail you get a BLUE field and flyback lines because the gun assembly is leaning on the shielding.
              you can even bodge that half the time by turning the tube upside-down so gravity fixes the short!
              Last edited by stj; 05-18-2023, 04:11 PM.

              Comment


                #8
                Re: I need help with my friend Sony GDM-FW900 24” CRT

                @stj perhaps you have an idea of what PS401 is responsible for? It is open for both sides. What type of electric circuit element it is?

                ^Also, no issues on the A board (with C block) and no cold joint on all boards. I have borrowed an ESR meter and checked all caps and they are fine (have not checked SMD ones). My desoldering kit is not a way for checking all caps blindly. I have no access to the scope as well.

                Also, I have attached the video of the same monitor behaving the exact way as mine, but the guy is still able to turn him on. And he did replace every single cap across all the boards.

                At this point let's assume a few things
                1) It's not caps
                2) It's not a bulb (if it starts working flawlessly)
                3) It's not an FBT (if starts working flawlessly)
                4) If's starts no brightness issues
                5) Scren is not flickering

                Let's focus on numbers and areas that can be failing (no magic heating stick - just please). Knowledge about CRTs in this particular case is required.

                Let's get back to the main question which part should I measure as a suspect in a smart way?
                Last edited by matthewmcconaughey; 05-20-2023, 03:12 PM.

                Comment


                  #9
                  Re: I need help with my friend Sony GDM-FW900 24” CRT

                  Hello again! I have performed some measurements around the G power supply and it has raised more questions.

                  G2 Voltage on A board = 0.00V
                  [G board (Power Supply)]
                  Measurements around IC610

                  C611 = 420V - (10) CATHODE but according to the Service manual it should be 376V

                  R643 = 0.0V
                  R629 = 0.0V
                  C639 = 9.3V
                  C648 = 14.8 V

                  R625 = 0.00V - should be 192V - (16) VG (H) (IC620 MCZ3001D SW REG CONTROL)

                  Those 2 resistors are on the red line going straight to (8) VC1 (IC620 MCZ3001D SW REG CONTROL)
                  R631 = 0.9V
                  R696 = 3.1 V

                  Out from VCC z IC610 - red line
                  R614 = 2.5V
                  C613 = 13.5V

                  C611 = 250V it is connected to (3) AC SEN IC610 (but in the Service manual it says it should be 86.2 V)

                  R620 = 0.0V
                  C643 = 0.15V
                  R621 = 97.0V

                  I don't understand what is going on with the R651 resistor, he is not present in any service manual
                  R651 = 73.0 V (photograph below)
                  https://imgur.com/cqDzTNZ

                  The leg of R651 is connected to (1) V SENSE and the voltage across resistors is
                  R651 and R621 = 402 V is connected to (1) V SENSE of (IC620 MCZ3001D SW REG CONTROL) but in the service manual is printed it should be there 1.7V

                  C645 = 2.2V (3) CT - OK - Service manual = 2.2V (IC620 MCZ3001D SW REG CONTROL)
                  C647 = 0.00V (6) TIMER - OK - Service manual = 0 V (IC620 MCZ3001D SW REG CONTROL)

                  Here, does it mean that C646 is failing and needs to be replaced?
                  C646 = 0.17V (7) SS - WRONG - Service manual = 4.5V (IC620 MCZ3001D SW REG CONTROL)
                  I don't understand why when I am touching with only one prob of the multimeter on the legs of C646 I have 2.7V readings (the 2nd probe is in the air, not touching anything)

                  C640 = 10.8V (10) VC2 - OK - Service manual = 10.3 V (IC620 MCZ3001D SW REG CONTROL)

                  C642 - 0.00 V
                  R625 - 0.00 V
                  R626 - 0.00 V
                  Attached Files

                  Comment


                    #10
                    Re: I need help with my friend Sony GDM-FW900 24” CRT

                    I have replaced C646 (2.2uF 50V) now I have voltage on him

                    C646 = 28V, the weird part is the monitor woke up and gave a screen with an OSD picture. But the picture was very bright with a greenish picture on it. I turned him off and was able to turn him on one more time. Now, when I turned on the monitor no change, but the voltage on C646 is present. But when I put a multimeter on C647 to measure voltage the monitor powered on again (only a few times).

                    I have replaced C646 again and noticed, the monitor power on the first try. Only once, again very bright. When he was heated with a hair dryer there was no over brightness.

                    I think the monitor was powered on because he was heated in this area.

                    Used to be C646 = = 0.17V (7) SS - WRONG - Service manual = 4.5V (IC620 MCZ3001D SW REG CONTROL)

                    Correct: now when I heat back the area for 30 seconds with the hair dryer he is always powering up very bright (I am turning him off, don't wanna harm him). Not sure how to locate which component needs to be heated (failing) and needs to be replaced. Any ideas?
                    Attached Files

                    Comment


                      #11
                      Re: I need help with my friend Sony GDM-FW900 24” CRT

                      Recently I had to pull my GDM-FW900 out of storage, and actually it's on my desk as we speak right now. It used to start out a little bright and settle down after ~30 minutes of use - that was when I last used it some 10 years ago or so. Now, it goes way too bright when it starts from cold and there are retrace lines everywhere for the first 10-20 seconds. Then it goes down a little after this, but takes another 10 minutes before it looks right... and after 30 minutes of use, it's too dark.

                      I think the truth is, these Sony G1 chassis monitors really have serious issues with the G2 voltage rail design and regulation. It's regulated by MCU and from what I hear, data corruption in the firmware keeps turning the G2 up and up, until monitor starts retracing really badly or even shutting off.

                      Yours might be (attempting to) run the G2 so high that it shuts off right away... possibly among other issues too.

                      For starters, try bypassing the self-biasing transistor circuit on the cut-off amp, as detailed here:
                      https://www.badcaps.net/forum/showpo...7&postcount=25

                      Then, if you can turn the monitor On one more time, use WinDAS software to correct the values for G2 in firmware. Some details on how to do that can be found in this thread:
                      https://www.badcaps.net/forum/showthread.php?t=16126
                      And here:
                      https://crtdatabase.com/faq/windas-i...tion-and-guide

                      WinDAS software can also be found here:
                      https://www.badcaps.net/forum/showpo...8&postcount=24

                      Now, I've never done it myself, but there should be links on the net on how to build a Serial to TTL cable with a MAX232 IC or similar if you don't have a cable.

                      Comment


                        #12
                        Re: I need help with my friend Sony GDM-FW900 24” CRT

                        Hello, there is an update, the monitor is now turning on. But it seems it's now harder for me to figure it out the main issue.

                        I have noticed that heating up IC620 powers on the monitor I think the 7 or 8 leg was responsible for that state. So I have replaced IC620 and the monitor is powering on every time but the screen is RED / GREEN.

                        I have noticed that shortly heating UP with a hairdryer back of PCB (not IC620) but closely around gives a proper picture for 2-4seconds (black background and this color input osd)


                        I have replaced 3 electrolytic caps around C645, C647, C646 but no difference

                        I think that there is something that killed IC and is doing this color problem (later CRT has proper colors after a very long time warmup and switching input 1 to input 2)

                        Any idea which type of component might be doing that, caps, res diodes? I don't know how to locate the component that is failing
                        Attached Files

                        Comment


                          #13
                          Re: I need help with my friend Sony GDM-FW900 24” CRT

                          The PSU output without heating the PCB
                          CN652
                          STB = 5V
                          80V = 79V
                          220V = 218V
                          12V = 12.0V
                          Heater = 5V

                          Moreover, when I turn the monitor on and off 5x times in a row each time, he has less red/green.
                          After 3 times, there is no red color anymore only green.
                          The picture is black after 2-5 sec -> green.
                          After 5 - 7, monitors turn on in the row picture stays black and has no color issue.

                          After that colors are normal permanently, this issue occurs only when the monitor is starting up and warming up.

                          Have no idea what is going on at this point.

                          Comment

                          Working...
                          X