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Power FET and 5 Watt 2.2 0hm Wire Wound Resistor Problem

By on April 11, 2016
philips 21 " crt tv repair

 

 

 

 

 

 

 

crt tv repair

 

The complaint by the customer for this 21″ CRT Philips TV was no power. No power problem can be due to the main fuse open circuit, bad On/off switch, bad power components, shorted components in the secondary side, dry joints and etc. No matter which component or circuit that can cause no power, one has to always check on the main fuse first.

When i measured the main fuse (as seen in the photo below), it was tested good. Even the On/off switch also tested good. If you are comfortable in checking the AC supply input, you may do so as different repairers will have different procedure in doing their troubleshooting job.

measure fuse

 

When i measured the main filter capacitor there was no voltage and this means there must be a component that had an open circuit preventing the current from reaching the main filter capacitor. So I began to check on the components after the main fuse and I found a 5 watt 2.2 Ohm resistor had an open circuit-see the photo below:

wire wound resistor open

 

Usually there will be a reason why the resistor had open circuit. The reason is most probably there is a shorted component (semiconductor) in the power primary side that had consumed too much power causing the resistor to open. Just before I check on the power FET, I saw that this FET pins/legs had dry joints as seen in the below photo:

power fet dry joints

 

I took the power FET and check and it was indeed shorted. I continued to check on all the components in the primary side including the SMD components and all were found to be good.

Note: If you want to learn the fastest and accurate ways to test components, I can recommend you Jestine Yong’s ebook on Testing Components.

checking surrounding components

 

The shorted FET part number was FQPF7N60 and finding it from the local market was not that tough. As for the resistor, since I can’t find the 5 watt 2.2 Ohm resistor, I have used 7 watt 2.2 Ohm as replacement.

bad fet and resistor

 

After fixing the components, I connected a 60 watt bulb in series with the ac supply to make sure that there is no longer short circuit.

light bulb series test

 

Once I powered the TV (with the series light bulb trick) I could see that the bulb was not bright and it went to dim straight away. I could also see the standby LED was lit which indicates a good sign I can put in the main fuse and power the TV up.

crt tv stand by problem

 

Once I put back the main fuse and turned the TV ON, below picture was seen. I’m glad that the TV was fixed and managed to earn some income from this repair work. If you want to learn how to repair CRT TV then you can get Humphrey’s Ebook HERE.

repairing crt tv philips

 

suranga

This article was prepared for you by Suranga Bandara who owns an Electronics shop in Anuradapura, Sri Lanka.

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P.S-  If you enjoyed reading this, click here to subscribe to my blog (free subscription). That way, you’ll never miss a post. You can also forward this website link to your friends and colleagues-thanks!

Note: You may check out his previous repair article in the below link:

https://www.jestineyong.com/dvd-spindle-motor-problem-repaired/

 

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12 Comments

  1. Humberto

    April 11, 2016 at 11:17 pm

    Good repair Suranga. Another device saved from the dump.

    Likes(1)Dislikes(0)
  2. Robert Calk

    April 12, 2016 at 12:11 am

    Good job, Suranga.

    Likes(2)Dislikes(1)
  3. Paris Azis

    April 12, 2016 at 3:31 am

    Good job, Suranga.

    Likes(2)Dislikes(0)
  4. Anthony

    April 12, 2016 at 5:40 am

    Good repair Suranga !

    Likes(1)Dislikes(0)
  5. Mark

    April 12, 2016 at 6:53 am

    Hey Suranga,

    As usual a great article. The leg of the FET looks pretty bad. Had it been near moisture? Was the track OK?

    Likes(1)Dislikes(0)
  6. Albert van Bemmelen

    April 12, 2016 at 3:16 pm

    Good repair as always!

    Likes(2)Dislikes(0)
  7. Parasuraman S

    April 12, 2016 at 11:00 pm

    From the first paragraph itself, I guessed it should be none other than Suranga Bandara! Useful info for people like me. Right now I am trying my best to sort out a complaint on a Samsung CRT TV, which has no picture, but only sound. The screen is a total black!

    Likes(1)Dislikes(0)
    • Suranga Electronics Sri Lanka

      April 14, 2016 at 1:50 am

      Hi Parasuraman,

      Is the CRT TV heater light On?

      Likes(0)Dislikes(0)
  8. Suranga Electronics Sri Lanka

    April 13, 2016 at 1:20 am

    Hi. All.
    Thanks So much !!

    Likes(0)Dislikes(0)
  9. Ezekiel

    April 18, 2016 at 1:56 am

    Great job well done sir.

    Likes(0)Dislikes(0)
  10. Michael

    June 25, 2016 at 1:39 am

    You are the best in the world this Panasonic TV gave me the problems for many years

    Likes(0)Dislikes(0)
  11. Teasfaye kebede

    October 18, 2016 at 11:30 pm

    good repair suranga

    Likes(0)Dislikes(0)

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