Monitor issue samsung syncmaster 753s

Discussion in 'General Electronics Chat' started by hkj, Aug 21, 2010.

  1. hkj

    Thread Starter New Member

    May 25, 2009
    3
    0
    The problem is that the horizontal size has decreased even though i had set the horizontal size to full.Pls help
     
  2. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Not many in here that give service advice, but I'd suspect the coupling capacitor that leads to the horizontal yoke winding.
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    Perhaps this pages will assist you with the repair (it will give some hints):
    http://www.repairfaq.org/sam/monfaq.htm
    http://www.e-repair.co.uk/tipsmon.htm

    Beware there are very high voltages present in CRT monitors:
    (from the given page)


    Bertus

     
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    And good luck gettting into it. Some aren't bad, most are so filled with shields there really isn't any practical option to servicing them.

    Sadly, exept for some of the most expensive CAD monitors of years ago (when they were curernt) there's little sense in trying to work on one anymore. People are constantly giving away good working monitors on craigslist and if this Sony-tbed Hitachi 21" CAD monitor didn't still have such a perfect picture I'd have replaced it with a flat screen years ago since it adds so much heat to my room.

    FYI: A true CAD monitor is unique because it's adjustable to and capable of producing absolutely straight lines both vertical and hoizontal without any distortion. I also have a backup Mitsubishi 21" sitting in storage at work that was also given to me free.
     
  5. tom66

    Senior Member

    May 9, 2009
    2,613
    213
    First, I would suspect a settings issue. There is usually a service method to reset the settings (for example holding down two buttons while turning the monitor on) though exactly what buttons and settings would only be known to Samsung.

    The second most common fault would be a power supply fault. I haven't had any CRT monitors with power supply faults, because the supplies are usually well designed, but it can happen. Check the filter capacitors; if any look bulged, attempt a replacement. But not before reading the scary warning below.

    Be incredibly careful when working with a CRT. Voltages of 25kV to 30kV are not uncommon for the EHT (the red wire leading to the tube.) Whilst the current is low and unlikely to be dangerous, touching this will send you flying across the room and that is where the danger lies. This voltage is even present when the monitor is unplugged because the tube acts as a large capacitor. Also, the focus voltage and other voltages coming out of the flyback can easily exceed 500V.
     
  6. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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  7. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Yea, if you're already a member of rapidshare fine, but from what I've found a few of these links are fake, you won't find a schematic or service manual once you've signed up. This one does look legit but it isn't my money.

    Having replaced dozens of those yoke coupling caps to repair the exact problem in many brands of monitors that's where my money rides, it's usually a medium size electrolytic, around 47 uF @ 250V with evidence of the electrolyte leaking from beneath it. Matters not, if that doesn't repair it it's not cost effective to try and go any further into the problem.
     
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