Re: Samsung UE58J5200 LED fail repeatedly

PSU checked again (MOSFETs and diodes): no shorts
D1 line voltage: 120V
D2 line voltage: 110V

Calculated current on R9162=1.58 Ohm power resistor is 0.115A.

Power voltages on all boards seems to be OK 12.75V, 1.5V, 1.0V depending on circuit and IC).

Backlit: one LED broken (no big deal)


After reassembling screen and replugging two T-CON flex cables there is an image (menu) but with ghosting:


Faulty LCD screen, T-CON board?

Next steps:...

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While main competitors like ST or Fairchild or Linear have different package which require PCB thermal pads / vias on PCB to dissipate heat the top line TNY290PG claim 36W in SO-8 package (magic!). Conclusion is yours.

Re: Samsung UE58J5200 LED fail repeatedly

Thank you for reply. I appreciate any advice however:
Cap seems to not to be a big problem now (PSU seems to be working but overloaded due to faulty LEDs - that is why TV is turned off).

When Q9101 is faulty (open/short) then there is no A13V so this is not my case but I did not have much time to analyse PCB trace / pads connections (maybe there will be some similarity with BN44-0632A schematic).

Re: Samsung UE58J5200 LED fail repeatedly

Next steps:

PSU:
1. Measure resistance and voltage drop on R9162. Calculate current.
2. Measure resistance of two LED channels (without and with load).
3. Measure all CNL802 voltages without load. Compare results with: [url]https://m.youtube.com/watch?v=xyw9AWLwCHU[/url]

4. Check MOSFETs / diodes for short (some are checked).
5. Replace leaked CM841 10uF/350V cap (capacitance and resistance is OK now).

T-CON:
1. Check three blue LEDs status (power supply voltage, fuse)....

Re: Samsung UE58J5200 LED fail repeatedly

Hi,

TV: UE58J5200
PSU: BN44-00787A

Backlit: [url]https://sklep-elwron.pl/pl/p/-LED-Samsung-UE58J5200-UE58H5200-DMGE-580SMA-R3-DMGE-580SMB-R3-CY-HH058BGNV1H/116[/url]
12 LED rails (6x DMGE-580SMA-R3 , 6x DMGE-580SMB-R3)
LED: 14 (7+7)

Symptoms: no screen / backlit on but dim

CNM803 (under load):
1,3,5,7 (A13V): 12.79V
9 (GND): 0V

CNL802 (under load / without load):
1 (D1+): 350V / 350V
2 (D1+): 350V / 350V
4 (S-): 227V / tbd...