|
|
|
#1
09-20-2014, 11:17 AM
|
||||
|
||||
|
no power?
I am "trying" to help a coworker with his lcd tv,
it is an rca Model # L37WD12YX1 40 inch set and he believes it is about 4 or 5 years old. OK, It has been fine until recently and here is what is does; It started when you hit the power button and it turned on but with a delay it never had originally. But still functioned great As time went on it came up slower and slower. Now the power button lights up but that's it......no sound or picture at all. just the lit power button. Any ideas? I am into the antique stuff so this will be my first modern set to look at. 
|
|
#2
09-20-2014, 11:59 AM
|
||||
|
||||
|
Check for bulged electrolytic caps on the PS. That model TV is famous for that
__________________
"It's a mad mad mad mad world" !! http://www.youtube.com/user/mwstaton64?feature=mhee
|
|
#3
09-20-2014, 12:00 PM
|
|||
|
|||
|
|
|
#5
09-21-2014, 08:39 AM
|
|||
|
|||
|
As in the video that WISCOJIM references, many times electrolytics can show no signs of failure externally (bulging, electrolyte leaking, etc). The best tool for "going around the boards" to quickly check them is an ESR meter which works in-circuit; as most all do. They are so cheap now, that IMHO it show be a mandatory test/measurment device right next to a DVM and the soldering iron.
Tom (PK)
|
| Audiokarma |
|
#7
09-22-2014, 06:14 PM
|
|||
|
|||
|
Quote:
|
|
#9
09-28-2014, 05:55 PM
|
||||
|
||||
|
The first pic is the main power supply and has at least 4 electro's that are bulged. The second shows what I believe to be the main and the standby board. When I try to turn on the set the signal line reads 5 volts dc....if I am checking the correct wires. The only others I saw are 120 ac volts. The third pic is the mini board and pointing towards the front is the signal line.....someone stop me if I am wrong! Yes the pics are not great but they were done with a cell phone in a dim basement .
Last edited by radio nut; 09-28-2014 at 06:06 PM. Reason: stupid cell phone spelling correction!
|
|
#10
09-28-2014, 06:05 PM
|
||||
|
||||
|
Just watched video again. So the 5 volts to the mini board signal it to send the 120 ac to the main power supply? If I am stating this correct then the mini board is good since the red/black wires going to the main power supply was getting 120 ac. The main board is the one with about 4 bulging caps.
|
| Audiokarma |
|
#12
09-29-2014, 03:29 PM
|
||||
|
||||
|
Caps that bulge their tops, even a little bit off of dead flat, need to go. Sometimes they leak out of the other end, though, so look there, too.
__________________
Reece Perfection is hard to reach with a screwdriver.
|
|
#13
09-29-2014, 10:52 PM
|
||||
|
||||
|
One thing I do not understand about the ESR meter....
I have seen plenty of times that a cap or electro will test good at low voltage and test bad at closer to rated voltage with a heathkit cap checker when the cap is out of the circuit. So How is an ESR meter supposed to help when it has a low voltage reference signal? The bulging caps tested fine with an ESR today over at Fair Radio here in Lima, Ohio. They Don't sell them but they keep one around for their tech to use.
|
|
#14
09-30-2014, 10:36 AM
|
||||
|
||||
|
I have tested ESR on bulged caps and most of the time they will test good. Their capacitance generally goes low. Any bulged cap is suffering from the "capacitor plague".
Never trust one. Also, test any small (47mfd or lower) capacitors on the power supply. Usually LG TV's have the small ones lose capacitance but I've seen almost all of the name brands and some no name have these problems.
|
 |
|
|
Linear Mode
