Help with LG TV 32LC7D power supply repair

[wilfred]

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[retiredcaps]

Some people say fuses die on their own due to age or fatigue.  In my limited experience in troubleshooting, that has never been the case.  If the main fuse popped, the usual suspects are shorted bridge rectifier, shorted power mosfet, etc.

[tautech]

I have a LG 32LC7D TV that shows no signs of life. I checked the fuse and it was blown. After examining the PS PCB for obvious signs of damage that might indicate a reason for the fuse blowing I found nothing and tried powering it up with a replacement fuse. I let the magic smoke out of what I think is a NTC Thermistor.

Usually a blown/shorted Mosfet in the SMPS but as retiredcaps says you need to look further.
Use a dim bulb tester to limit mains current on power up.

[retiredcaps]

Be careful when checking for shorts in the primary/hot side.  A couple of consumer electronics items that I have worked on over the last 4 years had 170V+ DCV stored on the big filter capacitor despite being unplugged for weeks!!!

Checking or discharging the big filter cap first is now my first step before doing any measurement.

For countries with 220ACV or PFC in the circuitry, the DCV could be as high as 400VDC.  A few weeks ago,  I worked my first device with PFC and saw 335V DC.

[Yago]

Be careful when checking for shorts in the primary/hot side.  A couple of consumer electronics items that I have worked on over the last 4 years had 170V+ DCV stored on the big filter capacitor despite being unplugged for weeks!!!

Checking or discharging the big filter cap first is now my first step before doing any measurement.

For countries with 220ACV or PFC in the circuitry, the DCV could be as high as 400VDC.  A few weeks ago,  I worked my first device with PFC and saw 335V DC.

Shariar from SignalPathBlog covered this very subject in his last vid.

[retiredcaps]

Shariar from SignalPathBlog covered this very subject in his last vid.

Yes, I was going to include that in my reply, but then got distracted and forgot. Thanks for linking it.