Samsung LN37D567F9HXZA dead power supplies, blown fuse

[crushkittykitty]

ended up getting 4 more from the hotel all with blown fuses. The person i get them from replaced the fuse in 2 of them said their was sparks lol. So I ended up with them. fixed one (gave to a friend), gave one to another friend he wants to try and fix it. 2 left and 3 power supplies all blown fuses. The fuse that was replaced fs8015 t5.0AH/250 was replaced with a 5.0a 250v slow blow glass fuse unsure if that added to the issue, will post pics of all 3 power supplies all 3 seem to have failed in the same location. replacing the power supply in the 2 tvs fixes the issue so I know it is just the power supply. Anyway I started pulling parts of one that was clearly burnt. In the morning I will post pics of all 3 front and back. all 3 show burnt marks see pic from edited shop jimmy was just figure there is more wrong then just these and am waiting for real fuses to come.

[jondoe]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

In the past I've used working boards as a reference for measurements of components, comparing them to the broken boards, this has sometimes allowed me to find problems fairly quickly. Get one of the tv's back of you friend for the day!

[dick_barton]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

The picture is too small to see what component(s) you are referring to as burnt. Is it the Mosfet on the heatsink or the blue capacitor?

[jondoe]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

CP811, I think, based on this picture.

https://www.tvpartsforsale.com/asset...N44-00439A.jpg

[dick_barton]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

Thanks for that.
Use your meter set to diode mode and with the power supply disconnected from the mains, test the Mosfets on the heatsink and the diodes in that area for any short circuit ( 0 ohms)

[crushkittykitty]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

In the past I've used working boards as a reference for measurements of components, comparing them to the broken boards, this has sometimes allowed me to find problems fairly quickly. Get one of the tv's back of you friend for the day!

I have 2 working exact same tvs think i will have touched all 48 of tvs from there lol
ill post some pics

[budm]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

Samsung BN44-00439A (PSIV181411A) Power Supply Unit
http://www.shopjimmy.com/samsung-bn4...pply-unit.htm#

Another bad snubber cap. Remove that cap and check its resistance to see if it shows any resistance, also check the resistance of the cap pads (cap is not in place to see if it shows low resistance).
Pictures provided by shojimmy.

[crushkittykitty]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

I took pictures of all 3 power supplies we are working on number 1 and a big thank you
TS68056 (cp8015) tested bad in board, taking it out made it alot better to get other parts out
fi 221k 1ku (cp811), has a blow out cp809 tested fine but will replace both
bp805,reads 701 one way open the other
bp806, short
bp8015 tests bad

[dick_barton]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

If the item circled is a ferrite bead it will show 0 ohms but is OK.

[budm]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

If cp811 (snubber cap for the PFC Booster diode) is shorted out or has leakage resistance, you will not have PFC Boosted Voltage, it will not cause any damage to the circuit, same result if D804 is shorted out or have leakage resistance. We have seen may of these caps and the Diodes failure before.

[crushkittykitty]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

If cp811 (snubber cap for the PFC Booster diode) is shorted out or has leakage resistance, you will not have PFC Boosted Voltage, it will not cause any damage to the circuit, same result if D804 is shorted out or have leakage resistance. We have seen may of these caps and the Diodes failure before.

So you think if I just replace cp811 and cp809 it will work?
retested the Ts6b05g its fine
all 3 are burnt in the same place have not tested anything else on the other 2, think I can get them local rat shack, that is a long shot they do have 30 phones but the parts are little to none.

as for fuses can a glass fuse (5.0 A 250v slow-blow glass) be used to test or should i just wait for the other fuses to get here?

[crushkittykitty]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

so this is were I am at right now.

[dick_barton]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

I prefer ceramic fuses because they don't shatter glass everywhere if they blow should there be a short circuit in the set.

[budm]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

So are you working on more than one board at the same time?
The one with shorted snubber cap for the PFC diode may not have other damaged part but I would check the MOSFET for the PFC at least, same for other boards.
So the one with shorted snubber cap for the diode, did it also blow the fuse?

[crushkittykitty]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

So are you working on more than one board at the same time?
The one with shorted snubber cap for the PFC diode may not have other damaged part but I would check the MOSFET for the PFC at least, same for other boards.
So the one with shorted snubber cap for the diode, did it also blow the fuse?

all have blown fuses there is 3, I have 2 tvs left that need power supplies. Working on just one at a time learning as I go. (the one marked with the black 1.) this one showed the least amount of damage. 1 blown snubber cap cp811
would that mosfit be the one in the center of the heat sink that I removed
see pics below.

btw. the other 2 show blown 2 snubber caps cp811, cp809

would that mosfit be the one in the center of the heat sink?

[budm]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

QP801S is MOSFET for PFC circuit.
xPxxx designator: P = for PFC circuit section.

[crushkittykitty]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

QP801S is MOSFET for PFC circuit.
xPxxx designator: P = for PFC circuit section.

learned something testing it shows not working. has alot of silicone coated on it will clean it off and test again have tested it 3 times once showed good if i can get the part number off of it will just replace it.

[petehall347]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

i do think something is shorted out causing the fuse to blow . mosfets first suspect . if so you must test components in that circuit that may have been taken out as well or might have caused the issue .
if you get this sorted you will know the main parts to build a kit to fix the others .

[crushkittykitty]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

its bad
QP801S STF13NM60N 11A / 600V
looking at it under microscope has a crack push on it tests fine lol
what is the last numbers on the mosfet chn 131 ?

[budm]

Re: Samsung LN37D567F9HXZA dead power supplies, blown fuse

When MOSFET shorted out, it can take out the IC that drive the Gate of the MOSFET with it too, so if you do not replace the IC and the MOSFET at the same time, you can take a chance of blowing up the new MOSFET.

"what is the last numbers on the chip chn 131 " Which IC is that?