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Why Horizontal Output Transistor In CRT Monitor Get Shorted?

By on November 2, 2007

horizontal output transistor 

There are many reasons why the horizontal output transistor (HOT) shorted in CRT Monitor.  Here are the possible cause:

HOT have life span-it can work for many years but out of a sudden it can just go shorted. Replacing only the HOT solved the probem!

Dry joints in nearby area- Yes, dry joints in the HOT leads, flyback transformer, horizontal driver circuits could cause HOT to blow.

Shorted flyback primary winding. I came across lots of HOT failure due to shorted primary winding in flyback transformer.  One of the best example was the HP 17″ 7500 CRT Monitor. Not only it blow the HOT, the B+ coil and the B+ FET blown as well!

Shorted or open internal capacitor in flyback transformer. These problems has contributed lots of HOT failure in CRT Monitor. Normally i will check the internal capacitor first before i replace the HOT and switch “ON” the Monitor.

Too high B+ voltage- A higher than normal B+ voltage will kill the HOT instantly. Make sure the B+ is supplying the right voltage to the primary winding of flyback transformer.

Running at wrong frequency- I once came across the horizontal driver circuit area was running at different frequency. It suppose to run on a 31.5 Khz (depends on resolution in your CPU setting) but  this faulty Monitor run at a too low frequency killing the HOT after “ON” for few hours!

Bad electrolytic capacitor in the supply line to horizontal driver transformer- If you found a HOT shorted make sure you check on this capacitor otherwise you may get a call back from your customer saying the Monitor not working again. The capacitor usually developed high ESR value that destroy the HOT in few hours to few weeks time.

Shorted horizontal yoke coils- A shorted horizontal yoke coil could instantly kill the HOT. I always use the dick smith flyback tester to confirm first that the yoke coil is good before the replacement of a new HOT.

Safety capacitor value out- If this safety (holddown) capacitor value dropped to zero, the high voltage produced at the anode could shoot up to over 30 kilo volt thus killing the HOT in a split of seconds.

Wrong replacement-The Monitor could be repaired by someone else and they had fitted a different specification of HOT thus making the HOT  won’t perform the best and breakdown after certain of time.

Nearby components- There are some possibilities too that the bad components nearby the HOT could cause the HOT to blow. Check the surrounding components before you switch “On” the Monitor.

Well, hope you can absorb these tips and start repairing CRT Monitor or TV with more confident! Have a brilliant day!

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  1. mahesh singh

    July 1, 2014 at 9:33 am

    I have a red screen problem in my onida igo tv please suggest me how it will remove the problem.

    • Jestine Yong

      July 1, 2014 at 4:28 pm

      Hi mahesh,

      Try check the RGB transistor and compare the Red transistor voltage/signal with Green and Blue transistor. Any different in voltage/waveform is a clue for you to troubleshoot on that area.


      • mahesh singh

        July 3, 2014 at 1:51 pm

        I also replace the three transistor c-2482 but not remove the red screen problem now what i do next.

        • Jestine Yong

          July 4, 2014 at 4:56 pm

          Compare the transistor voltage/waveform with the good one.


  2. Daniel

    July 17, 2014 at 9:26 pm

    please help my TV goes off after working for some few hours completely,but when you turn it on again it works and goes off again. I have changed the HOT but no avail,i changed the vertical output too the problem is still there, what should I do?

    • Jestine Yong

      July 18, 2014 at 8:14 pm

      HI Daniel,

      First is all the output voltages from the power supply good and stable?


    • Robert

      July 19, 2014 at 10:57 am

      Hi Daniel,
      I have a 42" Sanyo LED/LCD TV that is only 1 1/2 years old and sometimes it just turns off by itself. It will come right back on when I click the remote or push the on/off button and work fine. Sometimes when it goes off & I turn it back on, it might be a month or more before it turns off again, so I'm really not worried about fixing it right now. When it starts acting up more often I'll pull the back off and see what I can find out.
      Those intermittent problems are the worst!

  3. satish

    September 28, 2014 at 7:13 pm

    hi i have a Samsung 21" CRT TV .the problem is 'when turn on it makes ticking sound and no light no display ,just ticking noise. can anyone help?

    • Jestine Yong

      September 29, 2014 at 10:55 am

      Probably shorted HOT or some other components.


    • harinder rajbhar

      August 10, 2015 at 1:06 pm

      flyback transformer or horizontal driver transistor is short

  4. alege oluwole

    October 27, 2014 at 12:32 pm

    hi i av a 32inches crt jvc product they use c5552 as HOT there and it has shorted and i cant find it here bt if i used any other HOT it get burnt imeddiately watcan i used or do pls

    • Jestine Yong

      October 27, 2014 at 2:46 pm

      If you have checked the suggestion that I have listed in the article this means you have to use back the original part number. You can buy one from


  5. leo

    December 4, 2014 at 8:09 pm

    Samsung 29inch crt light only with tick sound ..please help me

    • admin

      December 6, 2014 at 11:19 am

      HI leo,

      You have to open it and check if the output voltages from power supply is good or bad. Sometimes a bad flyback or shorted HOT also could cause tick sound.


  6. Devarakonda venu

    December 8, 2014 at 2:26 pm

    These answere are fine.

  7. jose antonio m moura

    January 31, 2015 at 9:20 am

    very good !

  8. Rajeev

    June 11, 2015 at 6:51 pm

    Hai sir,
    My CRT TV has some problem like ,whenever its power on power LED blink with tic- tic sound after a few second it will off.what is its cause and remedy.

    • Jestine Yong

      June 12, 2015 at 11:24 am

      HI Rajeev,

      I suggest that you check the power supply first. If all the output voltages are good then suspect a bad flyback.


  9. kharpran

    June 17, 2015 at 4:12 pm

    Hi jestine my samsung crt tv is giving elongated picture and colour not properly converged.Pls give me some advice.
    Thank you

    • Jestine Yong

      June 18, 2015 at 9:15 pm

      Hi Kharpan,
      Is the picture curved inward or outward? Color not properly converged could be due to the pctube neck ring that had loosen or you may have to adjust the small preset in the convergence board.


  10. Abudi Idi Mwishahali

    July 23, 2015 at 1:11 pm

    I do appreciate your answers to our questions,may God bless you.

  11. Hussain Arif

    July 26, 2015 at 4:00 pm

    sir i have china Crt tv picture botom sid dark and upar sid ok sir i check vertical section all ok cap supply voltage sir pleas gave any way

    • Jestine Yong

      July 27, 2015 at 5:25 pm

      Hi Hussain,

      Have you tried replace the vertical ic and retest? Is the dc supply voltage to the vertical IC good?


  12. mahienn

    August 28, 2015 at 4:09 am

    Dear jestine sir or elder brothers plz attention..

    I'm looking for a diode (RGP02-12)
    But unfortunately its nt available in market
    could u plz suggest me any alternative parts substitute to this diode? Thanks in advance..

    • Jestine Yong

      August 28, 2015 at 3:35 pm

      HI Mahienn,

      Try this link:


  13. mahienn

    August 29, 2015 at 4:59 am

    Dear jestine sir thank u very much..
    I live in bangladesh
    could u plz suggest me which one can i use if diode
    (RGP02-12) is not available
    Can i use diode (IN5399) instead?
    If not then plz suggest me a few ones,
    thanks a lot 2u in advance..

    • Jestine Yong

      August 29, 2015 at 10:21 am

      Hi Mahienn,

      You need to replace with the same type (fast recovery) with the same or higher amp and volt. 1n5399 can't be used. Sorry I do not have any know replacement number other than the original one.


  14. mahienn

    August 29, 2015 at 2:36 pm

    Ok thank you very much sir.. God bless u..

  15. aQhila

    September 1, 2015 at 2:40 pm

    hello engineer,
    please I have problem with a "24" inches Samsung TV, whenever I replace its HOT it gets short immediately without being showing any picture.. I have changed it 4 times... please help me out!

  16. ssempala michael

    October 8, 2015 at 7:19 pm

    hp computer repaired in less than an hr. was given a dead computer for repair . step 1 i had to clean the mother board. after i powered it but no response i could see the standby light behind the power supply. i tried to switch on the computer again but nothing like starting. step 2 i disconnected the power supply from the mother board and loop the switch with a wire then powered it and the power supply started then i got hold of my meter and measured the voltages which are supplied eg 5v, 12v, 3.3v, and i found that 5v was insuficient ie i was getting between 4.7 and 4.8 instead of 5.7. then i had to oppen the power supply. to find 6 capacitors had swollen tops. like 10v, 3300 mf and 16v 2200mf. so i replaced all these capacitors. then powered again it started but the fan was not moving well so from here i realised the cause was too much heat spoilled the capacitors i replaced it with another fan. switched on again and it started well. when i measured i could get 5.3 v and other voltages were ok. so i connected back to the mother board the computer just worked well. thank u so much for your hints because i follow them send more sir.

    • Jestine Yong

      October 8, 2015 at 8:15 pm

      HI Ssempala,



  17. Rajib Singh

    November 15, 2015 at 7:44 pm

    Hello Jestine Yong, I have a china t.v "samsun" it was suddenly gonna dead. Then I replaced "c5287" transistor, after this replacement t.v will become okay. But 2 hours later t.v gonna dead again due to "c3807" transistor blast. (when i was replaced c5287 transistor then t.v will become okay, but after that replacement i found little bit more brightness, and 2 hours after c3807 transistor gonna blast.) what should i do now?

    • Jestine Yong

      November 16, 2015 at 11:47 am

      Hi Rajib,

      Check to see if there is any abnormal voltage or signal in the c3807 transistor and corresponding components. Make sure also the B+ supply voltage to the c5287 is good and stable.


  18. Krishnamoorthi A N

    November 21, 2015 at 3:25 pm

    Mr. Jestine Yong

    My Samsung colour TV CZ215KML power supply IC KA5Q0765RT burst out and I replaced the same with new one. Also short circuited diode F06U20S in the secondary supply replaced with a new one. While the power supply is on, the dial lamp not light up and the B+ shows 3V and B++ shows only 90V. How to rectify this?

    • Jestine Yong

      November 23, 2015 at 8:32 pm

      HI Krishnamoorthi,

      Is all the output voltages from the power supply good? Have you checked all he components in the primary and secondary section?



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