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Trinitron 19" CRT specs

Discussion in 'Electronic Repair' started by Michael Stan, Apr 7, 2004.

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  1. Michael Stan

    Michael Stan Guest

    I have 2 KDS monitors with Trinitron 19" CTRs. I had to change FLB's in both of
    them. I would like to know what the correct values would be for heater voltage
    (I found around 6.1V in both of them), G1, G2, HV on these tubes. Also for
    katodes. CRTs are M64LMS15X. I couldn't find any documentation at Sony. Somebody
    knows? Thanks.

    Michael
     
  2. Jerry G.

    Jerry G. Guest

    Depending on the CRT type used, some are 12V, but most are 6.3V. If you are
    at 6.1V and the CRT is having normal emission, then I would not worry about
    this. The tube heater should be having a nice orange type of glow, and not a
    very bright yellow. I you were to run a 6.3V heater on 12V, it would not
    last very long! The heater would be lit like a light bulb!

    The best way is to get the service manual (usually impossible for these), or
    to get the specs of the tube. I would not worry about this, if the monitor
    is working normally.

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    =========================================


    I have 2 KDS monitors with Trinitron 19" CTRs. I had to change FLB's in both
    of
    them. I would like to know what the correct values would be for heater
    voltage
    (I found around 6.1V in both of them), G1, G2, HV on these tubes. Also for
    katodes. CRTs are M64LMS15X. I couldn't find any documentation at Sony.
    Somebody
    knows? Thanks.

    Michael
     
  3. Michael Stan

    Michael Stan Guest

    Thanks, Jerry; I thought so. There is no adjustment for heater voltage on the
    board. As both boards showed the same reading (6.1V), I thought my DMM is a
    little off, at least on this range. I tried with another DMM and it read around
    6.3V. So here I'm OK.
    Because of the neck board I cannot clearly see the filaments, but I can see some
    orange reflections. I guess it's OK.
    I tried to get the service manual for this EVOKD-1910T, but failed. The business
    that sold me the flybacks, which is the one that's doing service for KDS in
    Toronto and around, refused to sell the manual. First they said they don't have
    it! When I insisted, showing my amazement they can do repair work without the
    manual, they admited having it, but refused to sell it. That's the situation.

    How about the other voltages, G1 and G2? Knowing the HV value wouldn't do me any
    good as I don't have a HV probe; but still I would like to know the right value
    for this tube.

    I have a strange problem with one of the monitors. It has a definite pink hue.
    When I put a white screen (with Nokia program) I get something like a pink
    screen. I can adjust from OSD but still the image is not right. On a black
    screen, If I increase the brightness I get pink retrace lines.

    Having 2 identical monitors allowed me to switch parts in order to pinpoint
    where the problem is. I tracked it to the mainboard. When I take the mainboard
    from the monitor that have good image and move it in the monitor with redish
    image I get a good nice white image. So, it is not the CRT, not the neck board
    (where the color guns drivers are located), not the small board where the VGA
    cable connects to the monitor, not the cable.

    I measured the DC voltages at the CRT pins for RGB with the bad mainboard and
    found: 33.3V, 46.8V, 42.2V (RGB). With the good board I got 36.1V, 38.4V, 33.8V.

    And I found something else strange on the bad board: the G1 fluctuates; with the
    same white image, it went from -1.72V to +6.73V. And it was still moving. (With
    the good board I measured -4.45V) Can this produce the redish effect I see? Is
    it normal for G1 to fluctuate? Should I look for something faulty in the G1 circuit?

    One more observation: I measured the ABL voltage (DC) and found 4.84V with the
    good board and 8.50V with the bad board. Maybe that's normal? (2 diferrent
    flybacks produce 2 different ABL voltages?)

    I would appreciate any idea. I'm not an electronist, just an amateur that tries
    to fix his own monitor. Thanks.

    Michael
     
  4. For someone that is doing this for a hobby, you atleast have some base
    understanding to what is going on!

    It does sound like the tube biasing is not right, when compared to the
    other monitor. There are a number of factors here. One is that the
    main power supply should be verified, and also the secondary voltage
    outputs from the flyback section. It is possible that there is a
    regulation fault, or voltage source fault.

    Also, look for any high ESR capacitors. If there are any that are not
    working properly, it would be difficult to have an exact theory of the
    effects without some research. But, I have had defective caps cause
    some very interesting fault conditioins.

    Without the service manual, you will be working sort of blind at this.
    The service rep most likely signed a contract of non disclosure about
    giving out copies of the service manual. When I was working some
    service contracts, with some of the manufactures we had to do the same
    thing.

    If all the components check out okay in your monitor, the service
    setup will have to be verified. For this you will definately require
    the service manual, and there may be an interface with software
    involved. Many models of monitors are like this.

    In the end, it may pay for you to send out the monitor and have the
    service rep fix it for you. The repair may be worth it for you, if the
    CRT is in very good condition, and if you find the monitor to be of
    value to you.

    Many of the service shops are jobbing out their work to the
    manufacture reps, if any dedicated adjustments, or service techniques
    are required. If in the end you determine this, then that will be the
    logical solution.

    Jerry G.
    http://www.zoom-one.com
     
  5. Michael Stan

    Michael Stan Guest

    Yes, it is something on the mainboard that's producing this.
    I checked the outputs of the power supply and they are in accordance with the
    schematics (in cases where the expected value is written on the schematics). All
    of them seem to be in good order. The heater voltage is not written, it is given
    only as a symbol, HT. That's why I asked here about it.

    The same stands for the FLB outputs, except for HV (which I don't know and I
    cannot measure anyway). I have a FLB line, on the same side as HV and ABL,
    called DF-IN. Do you know what it stands for? It may help me understand what the
    circuit connected to it is doing.

    Also, it is an FLB output marked on the schematics as +900V. This voltage raises
    when I raise the HV voltage (using the VR marked HV). Therefore I acted upon
    this variable resistance to bring that line at 900V, hoping that the HV line
    also comes to the right value (trying to use the measurment of the 900V as in
    indirect measurement of the HV). Does this look right to you?
    I followed this usual advice, and, since I don't have an ESR cheching device, I
    replaced all the electrolytic capacitors, on the entire mainboard, except the
    main line capacitor, for which I coudn't find a replacement (it's a 330uF, 400V,
    25mm diameter). I checked this one for capacitance with a DMM and it looked OK.
    Yeah, that could be the cause they don't want to sell it. I perfectly realised
    that I was blind without the manual. That's why I asked here for help. I don't
    need the entire manual, just the part or parts relevant to the problem I have.
    Hm. One more complication.
    After so many work hours that I have dedicated to it, it became somehow a
    pesonal thing, a "vendetta". I am "at war" with this bloody monitor and I have
    to win; otherwise I loose my self-respect. :)

    I thank you for your interest in my problem and I hope I'll be getting more good
    ideas from you and from this group.

    Michael
     
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