LG TV trouble shooting?

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Old 11-21-13, 04:11 PM
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LG TV trouble shooting?

My daughter has a LG LCD TV model 32CS460. She's had it for just over 16 months and it has quit working. The power light comes on but the screen does nothing no sound either. I've checked the capacitors and also re soldered them. Checked the two fuses with an ohm meter and they look like their alright. I hate to just throw it away doesn't anyone have any other ideas or a forum dedicated to this type of problem.

Bob
 
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Old 11-21-13, 07:20 PM
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Do you have any electronics experience ?

Newer electronics are not easy to service. That TV received pretty good reviews and I haven't found any common troubles listed.

Actually.... the problem you're having is the most common problem in most TV's. The main power supply is in protection or non start up mode. It could be a short in the set or just a power supply failure. There aren't many parts on the power supply board that are considered serviceable. That power supply board is replaceable.

If you wish to troubleshoot the set send me a PM with your email address and I'll send you the service manual. I can't post it here as most service manuals are proprietary and are not posted in the public domain. In that manual is a troubleshooting list of parts and voltages to check. I'll work with you if you have any questions.
 
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Old 11-24-13, 06:59 PM
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Pete,

Forgot to say I have little electonic experience.

I had a chance to look at the TV and check power at the P401 connection. I was able to confirm that pins 9 -12 have 3.560 volts. Next I found X201 clock, they want to to check hertz, I'm not sure if I did it right. Don't know if I should leave my DVM on the same setting or not. I left it on the DC volt setting and put a lead on each connection and didn't get anything. I need to check my DCM manual and see how to check hertz.

Checked manual for Htz and set it on AC volts and pushed the Htz button. Put the leads on the end of X201 and got 7.8 switched the leads and got 9.9, values range a little with leads touching X201. Manual says I should have 24 MHZ.
Bob
 

Last edited by unioncreek; 11-24-13 at 07:35 PM.
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Old 11-24-13, 08:45 PM
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Pete,

I wanted to investigate first her if the capacitor were good, the look good. My Fluke DVM will test micro farads so I checked against what they are listed as. Some cam out close, but others had readings way high. I even double checked them. Here's the results:

Capacitor. DVM
47. 50.8
47. 47.8

680. 3351
680. 3353
680. 3355

10. 11.2
10. 10.4

470. 2908

1000. 2905
1000. 2899
1000. 1534

No decimals in the larger numbers.

Bob
 
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Old 11-24-13, 08:47 PM
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Unfortunately I believe you need to check them out of the circuit or one lead disconnected.

I use an O'scope and check for AC ripple in the circuit.
 
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Old 11-24-13, 09:28 PM
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I wondered about that. Can a capacitor look good(no bulging of the cap, etc.) and still be bad? Just want to make sure their not be ad before digging into this too far.

Bob
 
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Old 11-24-13, 09:39 PM
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Yes... in an electronic applications the caps very rarely look bad. They don't usually puff up and or explode like you'd see on A/C type equipment.

In A/C applications..... the cap is used as a switch. When the circuit is fired up the cap is a dead short to start the motor. After a second or two the cap is charged and just hangs there.

In DC applications the caps are used to remove or filter AC from DC circuits. The caps are usually sized very close to their operating voltage which pushes them to their limit as well as they dry out from the constant heat.

If you only have a VOM to troubleshoot with.... then you'd first check the DC voltage on the circuit to make sure it's close and then switch to AC voltage. You should see a very minimal AC voltage. The more AC voltage.... more ripple and it interferes with the signal.

In your application you are looking for a power supply voltage issue so you'd check for your primary DC voltages first.
 
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Old 12-06-13, 10:04 AM
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PJmax,

I pulled the capcitors and checked them with my Fluke DVM and they all seemed to be OK. Would it be worth just replacing them to make sure their not the problem? I'm kind of at a lose, I'm not great with electronics.

Bob
 
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Old 12-06-13, 06:47 PM
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I was messing around checking the P201 connect it gave which pin was ground, 12V, etc. and found that some of the pins don't have the volts their supposed to. service manual listed the volts too that each pin should have. And said if the volts listed were not found that the power board should be replaced.

Bob
 
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Old 12-06-13, 10:14 PM
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In your application you are looking for a power supply voltage issue so you'd check for your primary DC voltages first.
I posted that a while back.

Using the schematic and a voltmeter you check for all power supply voltages first.
When you find a particular voltage missing that tells you which part or section of the power supply needs to be serviced.

You can just change the entire power supply board if you don't want to troubleshoot it.
 
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