Detect if electronic coil is damaged?

Replies

• 

  skipper

  It's just a little tricky to get more than a "maybe it's that thing" impression with a picture or a casual look.
  
  My advice is: take it to a shop that has the equipment, or get some yourself. I would also recommend the manual specifically for the TV model you want to look at fixing, a book on Electronics will be useful but you want to do as little debugging of the circuit design as possible - it saves a lot of time for starters. You don't have to be an expert etc.
  
  What your picture appears to show are choke coils across, maybe, the power rails to smooth the AC. If one of the rails is dead or overvoltage I would not recommend powering it up, you can still investigate the circuit when it's not live.
  From experience, the top coil of the three does look discolored. Can you notice a burnt smell when you get close to it? Does it or the other coils warm up? Usually the enamel cooks or goes dark when you cook a coil. If you get an internal short the coil is DOA.
• 

  bob2300nx

  skipper

  It's just a little tricky to get more than a "maybe it's that thing" impression with a picture or a casual look.
  
  My advice is: take it to a shop that has the equipment, or get some yourself. I would also recommend the manual specifically for the TV model you want to look at fixing, a book on Electronics will be useful but you want to do as little debugging of the circuit design as possible - it saves a lot of time for starters. You don't have to be an expert etc.
  
  What your picture appears to show are choke coils across, maybe, the power rails to smooth the AC. If one of the rails is dead or overvoltage I would not recommend powering it up, you can still investigate the circuit when it's not live.
  From experience, the top coil of the three does look discolored. Can you notice a burnt smell when you get close to it? Does it or the other coils warm up? Usually the enamel cooks or goes dark when you cook a coil. If you get an internal short the coil is DOA.

  I can not find really any info on this tv. It is made by electrograph which went out of business 3 weeks ago. Tv is about 4 years old so its not worth taking to a tv man.
  
  I smelt it and did not smell anything unusual. I did find a broken fuse which I doubt is the only problem but I am going to start with that.
• 

  skipper

  An experienced engineer might mention that replacing a blown fuse is often the shortest path to another blown fuse. You have to uncover why the coil looks discolored, why the fuse blew or you'll be replacing fuses.
  
  Have you looked at replacing the PS or not much hope of finding one?
• 

  bob2300nx

  skipper

  An experienced engineer might mention that replacing a blown fuse is often the shortest path to another blown fuse. You have to uncover why the coil looks discolored, why the fuse blew or you'll be replacing fuses.
  
  Have you looked at replacing the PS or not much hope of finding one?

  Yes I have. Surprisingly all the boards inside that have a manufacture listed are samsung, which makes finding it much easier. This board on ebay has the same model number as the board in my tv. There are slight differences like a few extra heatsinks. But I suspect is that electrograph took the basic board from samsung and added a few extra touches.
  
  #-Link-Snipped-#
  
  What im doing now is I figure if im throwing the board out anyways might as well try some cheap parts. Also if I have to buy a board and then solder on it then I figure I might as work on the board I have. I am pretty sure that board is the problem though as to which part I have no idea (other than the coil), reason being is that the other boards have very few capacitors, resisters, or anything that I would think could go wrong. The other boards are mostly for fans and AV input.
• 

  skipper

  Ok , have you considered that the coil isn't or wasn't faulty? The problem could be because a power transistor has failed, or an op-amp somewhere. Coils, resistors and capacitors are more robust. Usually electrolytics burn out first, then coils; capacitors and resistors are entirely passive they only make heat. Other parts can 'vibrate' to a thermal limit, when this is exceeded all the smoke inside them, is released. (?)
  
  Smoke is a very important component, that you really want to keep inside these parts. If you see smoke, it's usually already too late (to put it back)...
  
  p.s. that last is from the anecdotal engineer's manual, btw.