This CRT TV was brought to me by an elderly widow with complaint of not switching on. When I checked it, I noticed the ac cord had burnt at base of cover case. See cover.
I replaced ac cord and powered tv, tv powered on and see what appeared on screen below:
As you can see, it’s a horizontal line. With this I know the problem has to do with vertical circuit. So I removed case cover, clean board and perform visual checking, nothing suspicious. Then decided to do voltage test on the vertical IC pins,(No utc78040).
This IC has 7pins and one of it’s pins was having 0 voltage, so I suspect this IC. I then trace the track of this pin to a diode which was opened (1N4004).
Then I decided to check all components in vertical circuit in which I discovered some e – caps that are high in ESR values, tank e-cap had oxidized, see pictures below:
Then I try to remove IC by desoldering it out, but I got some track damaged as result of lack of experience ( doing this 1st time anyway).
So I replaced IC with LA78040, diode with 1N4007 and also other bad components, also repair damaged tracks pictures below:
Then connect everything together and power on TV.
The video and audio came up load, but picture is blur!!.What a disappointment!!.
So I suspected problem could be with either FBT or crt socket, I check on socket, it’s o.k. In my country, brand new fbt is not available, except those extracted from junk boards which I do not intend to use because it will not last. So the only option I have is to order it online.
So I inform my customer about this and she said she can’t afford the cost and moreover the TV is old fashioned. I was so much disappointed and felt bad I could not finish this repair work. This time “it’s the unfinished repaired work “.
This article was prepared for you by Imoudu Onwumah from Nigeria. He is 62 years old and has just 3 years experience in electronics repairs. I started career in hotel industry as a chef, but then I was doing repairs only in electrical repairs as a hobbyist. In 2018, I decided to learn about electronics which through Jestine’s electronics e-books and holding my hand, am an electronics techie today.
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