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TV Repair: some days you are unlucky...

JeffS7444

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I always remember back in the day, pre plasma and LCD, people always said “don’t ever open up and mess about with your TV, even if it’s been unplugged for a couple of days, there’s still some electrical components with enough charge to kill you”.

I assume there was some truth in this?

And does it still apply to modern TVs? Amir’s post got me thinking about this, I had forgotten all about it.

With CRT-type sets, it was customary to discharge via the flyback transformer anode clip, and I was always super-careful to do this. But even 50V stored in an electrolytic capacitor can scare the #@$% out of you if you suddenly discharge it! Even with modern circuits, it's always a good idea to probe some of the larger capacitors to ensure they're not still charged.
 

mansr

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But even 50V stored in an electrolytic capacitor can scare the #@$% out of you if you suddenly discharge it!
A large capacitor charged to 50 V will make a nice bang if shorted, but it can't directly harm you. You'll feel a slight tingle on wet skin, nothing more.
 

JeffS7444

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If you ever run into issues with the videoboard its most likely due to solder connections breaking apart and not the caps. Just grab the board and heat it in the oven for a while to reflow the solder. Fixed my dad's tv 4 times in a row and got him 2 extra years from it.

Much safer to use a soldering iron or hot air to do the task as most electronic components aren't designed to withstand sustained temperatures high enough to melt solder. On those rare occasions where I encounter broken soldered connections, it's usually where heavier components are mounted, or where there's lots of thermal stress.
 

Koeitje

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Much safer to use a soldering iron or hot air to do the task as most electronic components aren't designed to withstand sustained temperatures high enough to melt solder. On those rare occasions where I encounter broken soldered connections, it's usually where heavier components are mounted, or where there's lots of thermal stress.
The shit is broken already, you could use a heat gun to blast all the IC's one by one....
 

RayDunzl

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I always remember back in the day, pre plasma and LCD, people always said “don’t ever open up and mess about with your TV, even if it’s been unplugged for a couple of days, there’s still some electrical components with enough charge to kill you”.

I went to an electronics "trade school" in 1980. It wasn't too bad. You could learn something if you tried. Managed to get a "real" job and retire early.

One required course was TV repair. I'm not sure anybody ever fixed one, I didn't.

The instructor there was an old skinny man, short sleeves, kinda wild look to him.

Student: "I can't figure out what's wrong with this one!"
Instructor: "Let me take a look."
Sticks arm into back of set.
POW!
Instructor: "Well, you got B+!"
 

DonH56

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The other problem with using an oven as a soldering tool, aside from it being really broad-area and having a variable temp profile as stated earlier, is that all the food grunge outgasses and can contaminate whatever is on the board, and of course the board can outgas all sorts of nasty chemicals that will bind to stuff in the oven to be deposited on whatever you cook next.
 
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amirm

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And unluckiness continues..... Counted the minutes until the replacement power supply board arrived. It just came. Opened the box and saw this:

Samsung Power Supply Bad.jpg


Stupid capacitor is blown it (circled in blue). :( It is a used board with cobweb and such (see top right circle).

They pull these boards out of dead TVs and sell them with no notification that they are used and/or broken. Haven't even done a visual inspection before selling this.

Put it in the TV anyway and it just complains with blinking light.
 

cjfrbw

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The Curse of the Chinese Capacitor! Also, on microwaves. Repair guys know what's wrong before they even look at them, come out, replace a capacitor, then microwave works for a lot longer.
 
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amirm

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Oh, great... You can't send them email to get a refund. You have to call them. Then pay for shipping of the board back, and then they send you another one. If you want a refund, you have to pay for the board to be sent back and they hold 20% of your money. Ah, I am so spoiled by Amazon.....
 
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amirm

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Might be easier to troubleshoot your "new" PSU board at this point, annoying as it may be... you may be able to fix that with parts from the toasted board. Perhaps with a round of 12voltvids' videos for good measure.
I have repaired hundreds of piece of electronics. I put myself through college that way. So the skill is there. What is not is the time.
 

thyristor

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Most TV repairshops these days simply swap boards. Only when some specific parts are known to become defective these will be replaced on component level.
The repair business surely has changed over the years....
I am glad to have 'gotten out' about 20 years ago.

Here's two of such professionals at work.

 
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amirm

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Here's two of such professionals at work.

I like the way the one repair guy put the screws he took off in the shag carpet! Quick way to lose them that way.
 

DonH56

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I used to use an empty tobacco (chew) tin (not mine, from friends) but my boss objected so I switched to an empty saddle soap tin. At least once every 6-12 months I'd get in a hurry or just lazy and not put the cover in, then naturally knock it off and have to go searching for screws.
 

mansr

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I used to use an empty tobacco (chew) tin (not mine, from friends) but my boss objected so I switched to an empty saddle soap tin. At least once every 6-12 months I'd get in a hurry or just lazy and not put the cover in, then naturally knock it off and have to go searching for screws.
A magnet strip (as found on fridge doors) is useful in these situations.
 
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amirm

amirm

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A magnet strip (as found on fridge doors) is useful in these situations.
They make them that way now. I have a bunch of these:

1584995955537.png


Every time I go to Harbor Freight (cheap tool chain in US) I pick up another.
 

DWPress

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I don't know if it applies but there are generic driver boards for laptop screens and such. I assume you don't necessarily need the "smart TV" functions if you've got a AppleTV, Roku, etc that provides online content.

At any rate, Kudos to you @amirm for not just tossing it and trying to make the repairs!
 
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