How To Repair Crt Tv With Vertical Lines

A friend of mine called me to cheque out his Tv which had a problem, As usual I took with me minimum test equipment, digital meter, screwdriver, iron gun and some soldering wire.

Upon reaching his place he was out of the house only the children were around, Afterward introducing to them my mission, they pointed to me the Television.

I wanted to know a brief history of the TV and i of them who was there equally the Television receiver went down told me that she was just watching a program and saw a line on the screen and that was the end of the TV program.

Now, once I heard a line on the screen two things came to my mind, Information technology is either a vertical or horizontal problem and to make proper conclusions I inquired from her how was the line oriented.

I mean was it across the screen or vertical? Her reply was vertical line.

I applied power to the ready and indeed I was able to get a blue line from top of the screen to the bottom.

Get-go conclusion: The fact that there is something on the screen means the FBT,HV,HOT, heater, screen and the power supply are okay and no need of troubleshooting(testing)

For those who are new to CRT television repair let me betoken out that whenever y'all become a vertical line on the screen, this usually points to a problem on the horizontal excursion and when you become a horizontal line on the screen then this symptoms points to a problem with the vertical circuit(it is merely the opposite)

So with that I concluded that the problem is on the horizontal excursion in particular horizontal deflection (width) excursion.

This includes horizontal yoke, S-correction capacitor, linearity coils not forgetting dry joints on these components.

 You can chronicle to the actual components here.

Again let me point out hither that the most probable crusade for this is open circuit or component and not a shorted component, A shorted component will load down the prepare such that it will not even first.

With that I decided to open the prepare and went direct horizontal deflection excursion and this is what I saw.

C435 was burnt across recognition; the rut was and so intense that it affected the neighbour (C438)

Without touching the meter I ended that I have got the culprit even before taking the board to my work bench.

I took the board with to my store and subsequently close observation I realised this capacitor C435 is actually a Snubber capacitor (it was placed in parallel with capacitor C438 (big ane)

Since the HOT was not shorted, we can conclude that C438 is still doing its job of protecting the HOT.

Then I was very sure that even if I replace this capacitor which was burnt information technology volition not solve the trouble.

So I turned the lath the other side and I noted a burnt marking and I was interested to know which component leg was it.

Upon close ascertainment I noticed information technology was really one pin of the horizontal yoke (Now I am getting somewhere)

The dry out joint was so big that we can call information technology a pothole and therefore needed no meter to confirm

This explains the vertical line on the screen and I re-soldered it thoroughly.

Back to capacitor C435, This capacitor was burnt completely and therefore the part number was missing.

To go round this problem, I took some other junk china Boob tube board in my store and checked the value of this capacitor.

The ane I got had two capacitor marked 822J 1600v and the other in 332J 2000v, a nd the one I was repairing had 1 capacitor marked 922J ane.6Kv and the other was missing (burnt).

And then I decided to do some calculation to figure out the burnt capacitor value.

Kickoff let me point out here that all ceramic capacitor come with body marks and the commencement affair to is to interpret them, I take done a detailed method on en-cording them in my basic electronics course book.

For now permit me say that the mark on ceramic capacitor body are in pF (but write down the offset digit and the second digit as they appear on the capacitor body and the tertiary is the number of zeros to add after the first two digit.

In this example 822 will be 8200pF and 332 will be 3300pF, now since the capacitor are bundled in parallel we volition add to get the total capacitance and hence we get 11500pF, And so any combination of capacitor to substitute must be effectually that figure.

I connected checking the junk board effectually and I finally got one cap 322 from a CRT junk monitor board and replaced the burnt one.

Now I have total capacitance (8200+3200=11400pF) which is within our working.

Please note that I as well replaced the partially burnt capacitor because I figured out that it will exist a matter of fourth dimension before it also succumbs due to injuries sustained from the burnt neighbour C435.

When replacing the snubber please consider also the working voltage of the snubber which must be the aforementioned used on higher.

Never use a capacitor rated 400volts as snubber, should be at least 1200volts and above.

After replacing the two components and re-soldering the dry joints, I went back to the owner and re-assembled the ready and after applying power everything went well and the TV was dorsum to normal.

Thank guys

Talk before long.

Source: https://www.electronicsrepairmadeasy.com/2016/03/china-tv-with-vertical-line-repaired.html

Posted by: krierequadvance.blogspot.com

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