Cracking a crt....

Discussion in 'Mac Basics and Help' started by BiggeeC, Aug 21, 2005.

  1. BiggeeC macrumors regular

    Jun 23, 2002
    Gaithersburg, MD
    Hey eveybody. I don't know if any of you have seen a recent post of mine regarding my problems w/my new Frankenmac Sawtooth (or, if you did see it, if you care). It seems that thread has died. So, since I did not solve my problems there, I have a new idea, which would bring us to this new thread. Here goes. Basically, I have a Samsung 19" flat screen CRT. The picture is blurry as all hell. I've changed every setting, both on the monitor and computer. I don't want to buy a new one because the purpose of building my Sawtooth was to have fun, spend very little money, and try to fix problems that arise (which I'm doing).

    So, to make a long story short (too late), one suggestion was to open up the monitor itself, and adjust the focus that way. A friend of mine says it's possible to do, and that he had it done to one of his years ago. So.....big question-who knows how to do this? I AM WILLING TO DO IT. I paid $25 for the monitor, and won't be too upset if I break it. Please help. Thanks!
  2. CanadaRAM macrumors G5


    Oct 11, 2004
    On the Left Coast - Victoria BC Canada
    OK: Unless you have experience and the correct non-conducting tools DO NOT DO THIS. There is voltage inside the monitor case sufficient to kill you, even with the power turned off.

    It can be done, obviously, with the correct safety procedures, tools and training. But you would be better taking this to a TV repair shop that also does monitors, and pay them $35 to do it.
  3. BiggeeC thread starter macrumors regular

    Jun 23, 2002
    Gaithersburg, MD
    $35?!?!?!?!?!?! Wow, I thought it would be much more than that. And ugh, I don't really want to kill myself, you know? I guess that pretty much answers this question.
  4. spinne1 macrumors 6502a


    Mar 12, 2005
    Hermitage, TN USA (near Nashville)
    I too recommend you don't fool around inside the case....but, I admit I have done it plenty of times with a very healthy level of respect and care. I also have a good idea what not to touch. Firstly if you want to do it, place the monitor on a sturdy flat surface (unplugged for a few days). Now, disassemble the outside part of the monitor. Don't touch the suction cup looking thing. Under there is a potential charge of electricity. Also avoid the capacitors, which are the larger round colored plastic things sitting upright with a flat smooth metal top, and which are soldered to circuit boards. Also avoid touching the circuitry at the neck of the CRT (the copper windings and such), and the circuitry on the video board, which is the thing attached to the very rear of the neck of the CRT (not all of this has a charge, but it is fragile so leave it be).

    To properly do your task you need a plastic Phillips screwdriver made for not conducting electricity (get one at a good electronics parts store or online). Your focus pot will generally be on the body of your flyback transformer. What is that? Well, it is the (usually) black plastic thing where the fat red wire goes at the opposite end of the suction cup which is on your actual CRT tube. The other end if you follow it goes down toward the circuit board below the monitor and into a black plastic thing a few inches square. That black thing is your flyback transformer. It's job is to generate mucho volts for your CRT. Anyhow, on the side of the flyback facing outward, you should find one or two adjustment pots. They may be inside a hole in a metal protective casing around the circuit board. If you shine a flashlight in the hole you will see the adjustment thing with a Phillips screwdriver slot. Often, the pot will actually say "focus" right on it or near it. The other adjustment may say what it is as well (but I can't remember what it will be). To adjust, carefully place the monitor in such a way that neither you nor anyone else (like a pet) could fall on to it, or accidently touch the dangerous parts while it is running. Next, hook it to your computer. Next, plug it in the wall and turn your computer on while the monitor is open and exposed (but with everything inside still hooked up). Open a page of fine text (this web page is a good choice if your font is set small) Next, use either thick gloves or a thick piece of rubber to grab the plastic screwdriver (I am a sucker for being extra safe) and carefully move it into position in the adjustment slot on the flyback. Now, while looking at the monitor slowly turn the focus pot both ways until you find the best focus. You may also adjust the other pot to see what happens, but try to note where you started so as to be able to return there. If this does not fix your focus problem your monitor may be shot.

    Good luck.

    (PS Okay I admit it, I have actually done this with a METAL screwdriver with a normal plastic handle--while holding it with a THICK rubber floor mat folded over a few times--I was very careful not to touch the metal surrounding the flyback.)

    PS II Does your monitor have several adjustments available via the front buttons and submenus and such? (mine does)
  5. BiggeeC thread starter macrumors regular

    Jun 23, 2002
    Gaithersburg, MD
    you know what spinne1? I think I'm going to go w/ canadaram's method. have someone fix it for me. Thanks anyway.
  6. applemacdude macrumors 68040


    Mar 26, 2001
    Over The Rainbow
    its usually not worth it fixing a crt

    very dangerous to work inside of one
  7. iEdd macrumors 68000


    Aug 8, 2005
    CRTs have great capatitance in them. Sometimes they can contain lethal voltages for months... I can suggest if you open it... Unplug it then try turning it on a few times, hopefully discharging it.. Then wear gloves and use non-conductive tools and the like..
  8. cardiac dave macrumors regular

    cardiac dave

    Jun 23, 2005
    And leave a note to your next of kin - directing them to this site if things go bad for some reason and you can't update us on the status of the repair ;)
  9. mpw Guest

    Jun 18, 2004
    I say go for it. Technology wouldn't advance without people like you willing to go that extra mile in search of discovery!!

    Obviously don't I'm joking :eek:
  10. BiggeeC thread starter macrumors regular

    Jun 23, 2002
    Gaithersburg, MD
    Quite possibly the funniest thing I've heard in about 3 weeks.
  11. doucy2 macrumors 65816


    Jul 7, 2005
  12. dornoforpyros macrumors 68040


    Oct 19, 2004
    Calgary, AB
    I have a very simple guide to cracking open a CRT

    -Digital Camera(VERY IMPORTANT!!!)
    -Tall Building/parking structure/balcony

    1)Carry CRT monitor to the top of said structure
    2)Throw off edge and watch it smash on the ground
    3)Take pictures and post on

  13. mpw Guest

    Jun 18, 2004
    You must've missed this post then.
  14. mpw Guest

    Jun 18, 2004
    The following concerns a question in a physics degree exam at the University of Copenhagen:

    "Describe how to determine the height of a skyscraper with a barometer."

    One student replied:

    "You tie a long piece of string to the neck of the barometer, then lower the barometer from the roof of the skyscraper to the ground. The length of the string plus the length of the barometer will equal the height of the building."

    This highly original answer so incensed the examiner that the student was failed immediately. The student appealed on the grounds that his answer was indisputably correct, and the university appointed an independent arbiter to decide the case.

    The arbiter judged that the answer was indeed correct, but did not display any noticeable knowledge of physics. To resolve the problem it was decided to call the student in and allow him six minutes in which to provide a verbal answer that showed at least a minimal familiarity with the basic principles of physics.

    For five minutes the student sat in silence, forehead creased in thought. The arbiter reminded him that time was running out, to which the student replied that he had several extremely relevant answers, but couldn't make up his mind which to use. On being advised to hurry up the student replied as follows:

    "Firstly, you could take the barometer up to the roof of the skyscraper, drop it over the edge, and measure the time it takes to reach the ground. The height of the building can then be worked out from the formula H = 0.5g x t squared. But bad luck on the barometer."

    "Or if the sun is shining you could measure the height of the barometer, then set it on end and measure the length of its shadow. Then you measure the length of the skyscraper's shadow, and thereafter it is a simple matter of proportional arithmetic to work out the height of the skyscraper."

    "But if you wanted to be highly scientific about it, you could tie a short piece of string to the barometer and swing it like a pendulum, first at ground level and then on the roof of the skyscraper. The height is worked out by the difference in the gravitational restoring force T =2 pi sqr root (l /g)."

    "Or if the skyscraper has an outside emergency staircase, it would be easier to walk up it and mark off the height of the skyscraper in barometer lengths, then add them up."

    "If you merely wanted to be boring and orthodox about it, of course, you could use the barometer to measure the air pressure on the roof of the skyscraper and on the ground, and convert the difference in millibars into feet to give the height of the building."

    "But since we are constantly being exhorted to exercise independence of mind and apply scientific methods, undoubtedly the best way would be to knock on the janitor's door and say to him 'If you would like a nice new barometer, I will give you this one if you tell me the height of this skyscraper'."

    The student was Niels Bohr, the only Dane to win the Nobel Prize for physics.
  15. rainman::|:| macrumors 603


    Feb 2, 2002
    I've done it myself plenty of times, but I'm the type of person that took apart toasters as a toddler. So agreeing with your decision and most others here, go professional, it's not worth risking your life (doesn't that sound dramatic, for a piece of equipment like this?)
  16. jdechko macrumors 68040

    Jul 1, 2004

    Halarious, I've read that one before, but it was a good read again.

    It reminds me of the Philosophy final exam story. The question: "Why?" One student finished in 30 seconds and answered "Why not?" or "Because" Depending on what version you read.
  17. wdlove macrumors P6


    Oct 20, 2002
    I had an Apple CRT. It made a crackle sound and then a burnt smell. Took it to the Apple Store. The Mac Genius said it would have cost $650 to fix. So needlessly to say I purchased a new 17" LCD.

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