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General Circuit Board Repair Question

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djm5220

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Specifically regarding an LG 60PV 450 plasma TV, but really just a general circuit board repair question: The solder connecting the 3 coils mounted on the Y-sustain and Z-sustain board have a known tendency to crack - see upper right of photo. But I have a far more drastic problem in the lower left of the photo, where the board has been burned, apparently by shorting. Is this even worth attempting to repair by resoldering, or is it beyond repair? Thx.
20180812_100350.jpg
 
yikes
 
Is this even worth attempting to repair by resoldering, or is it beyond repair? Thx.
Click to expand...
Impossible to answer from here because we don't know if the board is burnt through all layers internally (if any) and on the other side, or if the component is damaged or not.

But IMO, sure it is worth trying to repair by resoldering. That costs nothing but a little bit of your time.
 
natr0n said:
yikes
Click to expand...
Agreed!

Bill_Bright said:
Impossible to answer from here because we don't know if the board is burnt through all layers internally (if any) and on the other side, or if the component is damaged or not.

But IMO, sure it is worth trying to repair by resoldering. That costs nothing but a little bit of your time.
Click to expand...
True enough. And while I'm in there I might as well touch up the other 5 joints as well - they don't look particularly healthy. Thank you for the reply.
 
Whole thing looks cracked straight through. And its gone through a ground plane, looking at that peeled up copper. Other stuff on that plane may be affected if so. Hard to say at a glance. If youre lucky thats just a big trace. Really hard to know the real extent of the damage inside the pcb. On the bright side it looks like a simple pcb... might not be much under there.

Thats a big "i dunno, man..." Likely nothin but a big short straight through the board now. Sucker got HOT to crack like that. I definitely LOOKS bad. Still anything is possible.

Id still try. Get it cleaned up as much as you can and try it out. Plug it in and duck for cover lol.

Also solder cracking... not enough heat, not enough flux, or maybe bad lead-free... or some combo. Its not taking or setting like it should if its cracking like that.
 
With all respect to Bill and his past experience, that appears to be a resistor that failed to do it's job, and now has to be replaced and still may not work.
The PCB is too severely burned IMO too.
 
djm5220 said:
Is this even worth attempting to repair by resoldering, or is it beyond repair? Thx.
Click to expand...
Resolding would work to bridge the faulty circuit break, but it would not fix the potentially faulty components that may have caused it in the first place. It's worth a try, but be prepared to buy a new TV if you don't find and fix any other problems.
 
What does it look like on the other side?
 
This is a symptom of something else
 
Lots and lots of prepwork to clean it, something else failed, by the time you repair it you could get another board.
 
Caring1 said:
With all respect to Bill and his past experience, that appears to be a resistor
Click to expand...
And with all due respect, do you have X-Ray eyes and can see the other side of the board? Typically resistors have small leads and if I had to guess, they would be where you can easily see the "bent" wires that are soldered.

Also, if you look at that picture, you can see printed on that circuit board, the image of a coil between that burnt lead and a similar lead to its right. So I don't believe it is a resistor but since we cannot see the component side of the board, I cannot be sure.

That said, if it is a resistor, and it is not badly discolored from heat (or burnt to a crisp), remember "Better be right or your great big venture goes west" (I was taught a different phrase way back in tech school that would be offensive today). A resistor is usually very inexpensive and easy to replace. But I suspect what ever created the excessive current would burn out the new resistor too.
 
Sure give it a try...but it is nearly pointless. There are complete traces that are burnt out that you will need to jump. Actually the resistor will be the easiest part. Plasma's have a ton of amps flowing in them so be careful. There are capacitors that store huge amounts on these boards so be very careful and if you know how to discharge caps I would do that first thing.
 
inductor symbol
 
Bill_Bright said:
Yup! A coil represents an inductor.
Click to expand...
Or a simple electromagnet, if part of a relay. Or the primary/secondary winding of a transformer, if shown parallel to another coil(one of which being the primary winding, the other being the secondary).
 
MrGenius said:
Or a simple electromagnet, if part of a relay. Or the primary/secondary winding of a transformer, if shown parallel to another coil(one of which being the primary winding, the other being the secondary).
Click to expand...
Except the specific symbol printed on that specific PCP (the subject of this thread) is not the symbol typically used for a relay or transformer. It is a symbol commonly used for an inductor.
 
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