Samsung LN40C630 "No Signs of Life"

[coppercitycomputer]

Got in a Samsung LN40C630 40" LCD. No signs of life, no lights no clicks northing looks bad.

Where do I start? I have 170V DC across both the yellow caps on the power supply board. Fuse is good

[Alastair E]

Re: Samsung LN40C630 "No Signs of Life"

STBY 5V present?

[coppercitycomputer]

Re: Samsung LN40C630 "No Signs of Life"

I don't think so, but I am guess on where to test, I unplugged the power cable to the main board and did not get any voltage readings on any of the pins!

[martino]

Re: Samsung LN40C630 "No Signs of Life"

I don't think so, but I am guess on where to test, I unplugged the power cable to the main board and did not get any voltage readings on any of the pins!

No insult to skill but how did you test the voltages?
Black probe on chassis,red probe on pins,DMM on 20V DC?

[coppercitycomputer]

Re: Samsung LN40C630 "No Signs of Life"

Yes correct! No worry's.

No insult to skill but how did you test the voltages?
Black probe on chassis,red probe on pins,DMM on 20V DC?

[coppercitycomputer]

Re: Samsung LN40C630 "No Signs of Life"

Anyone have any ideals on what the problem is?

[martino]

Re: Samsung LN40C630 "No Signs of Life"

I don't think so, but I am guess on where to test

Here is the diagram for your powersupply...

[Alastair E]

Re: Samsung LN40C630 "No Signs of Life"

Well--I would check why there's no 5V from the PSU--The set won't do anything at all without that present....

[coppercitycomputer]

Re: Samsung LN40C630 "No Signs of Life"

My skill level is very limted, if you tell me to test a part I can do that, I don't know how to troubleshoot things. So if you could guide me a little bit, only the 2nd set I have worked on so far. Thanks.

[coppercitycomputer]

Re: Samsung LN40C630 "No Signs of Life"

The power supply is like $20 bucks on ebay is there anyway to pin point to power supply or main board?

[martino]

Re: Samsung LN40C630 "No Signs of Life"

With a complete absent of 5volt standby etc you can be fairly certain the psu is faulty for sure. Hard to test mainboard without psu.

[Glitcher]

Re: Samsung LN40C630 "No Signs of Life"

I would check the diodes, caps, mosfets, and other parts on the secondary side of the psu.

[ben7]

Re: Samsung LN40C630 "No Signs of Life"

Actually the PCB has the markings on it to tell you which pin is for which voltage on the output.

[budm]

Re: Samsung LN40C630 "No Signs of Life"

What happen if you unplug the cable between the main board and this power supply/inverter board combo? Backlights come on?

[coppercitycomputer]

Re: Samsung LN40C630 "No Signs of Life"

Budm, unplugging the main board has no affect. No backlights.

Glitcher, I don't know what the secondary side is or how to check diodes or mosfets, I can check caps but my meter only go's to 400nf.

[budm]

Re: Samsung LN40C630 "No Signs of Life"

Check those components (ZDxxx, CMxxx, RMxxx) I circled in red, check with both Diode mode and resistance made, use cap meter to report the capacitance (since you do not have ESR meter we can only di o capacitance for now). Check and report the resistance readings between Ground pin (5) of ICM801 against all other pins. TV not plugged in during test.

[coppercitycomputer]

Re: Samsung LN40C630 "No Signs of Life"

Budm, IC801 is blown in half literally. So is RM807. could not see it that well in the set. Do I still need to test the other parts? I assume that those two and there supporting parts will need to be changed? Please see photo.

[budm]

Re: Samsung LN40C630 "No Signs of Life"

When that IC is blown up, you do need to check all those components since the high voltage can dump into those components. You are better off with new board if the board is only $20.

[coppercitycomputer]

Re: Samsung LN40C630 "No Signs of Life"

Thanks, I will order the board from ebay and post back. Thanks for your help!

[coppercitycomputer]

Re: Samsung LN40C630 "No Signs of Life"

Quick follow up, Installed the used power supply from E-bay and the TV works great. My 2nd successful repair thanks to this forum!