Don't Miss

Electric Shock From Heatsink?

By on April 15, 2009


During my early day in Monitor repair there was an old NEC 14″ CRT monitor that came in for repair with the complaint of no power. Since i donot have the original part number i had use a substitution part number. After the replacement of the HOT (not original part number) i wanted to test whether the new substitution HOT would work or not, i used my finger to touch on the heatsink. I did not expect that i would get a shock from the heatsink! My finger developed a sharp pain and it lasted for few hours. Normally by touching on the heatsink or the HOT one would know if the substitution HOT will last long or not.

I began to inspect why the HOT heatsink could have current in it. Later i found that this design actually have the HOT collector (the HOT metal plate body) directly connected to the heatsink. In many Monitors, usually the heatsink is the cold ground. I had learned my lesson from that day onward that do not simply touch any electronic parts in it if you are not really sure of what you are touching.



  1. John

    April 16, 2009 at 3:39 am

    Jestine I'm glad to read and learn from that mistake!!! I would have never imagined
    that a heatsink would have current either.
    I could picture myself finding out just as you did 🙂

    Thanks for the heads up!!!

  2. admin

    April 17, 2009 at 9:01 am

    Hi John,

    Nowadays all current monitor models only use the insulated HOT but we still have to make sure of what we are touching. Have a good day!


  3. laxman singh

    December 9, 2009 at 10:55 pm

    when i change the horizontal output transistor 5802 it became short i had change three tr. change but i did not found the probem please tell me that what the reason of short of the tr.

  4. admin

    December 10, 2009 at 7:08 am

    HI Laxman,

    Try this link:


  5. alvin

    March 6, 2012 at 10:37 am

    good illustration sir....:)

  6. dalganjan kurre

    February 4, 2017 at 9:12 am

    in crt tv heat sink not connected to ground can cause some problem in screen?

    • Jestine Yong

      February 6, 2017 at 7:44 am

      Hi Dalganjan,
      The heatsink will usually not cause problem in screen.



Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.