Sony KD-65X750F - no lights/picture/sound

[brad2157]

I searched the forum first, but could not locate anything with this model Sony TV.

Sony KD-65X750F

There's good AC power going into power supply board. There is no standby light lit on the TV / no picture / no sound using either remote control OR power button on TV. I'm new at troubleshooting TV's, so here are the measurements I took. I am leaning toward thinking it's a main board issue, but wanted to see what others with experience thought. Anything I can go further test to help isolate the issue?


CN6401 Connector Pin measurements:

ODD Pins:
1 NC - 0 VDC
3 BL_ON - 0 VDC
5 STBY3 3V - 3.48 VDC
7 AC_OFF_DET - 3.48 VDC
9 POWER ON - 0 VDC
11 GND - 0 VDC
13 REG12V - 0 VDC
15 REG12V - 0 VDC
17 REG12V - 0 VDC
19 GND - 0 VDC
21 GND - 0 VDC
23 GND - 0 VDC
25 TCON_VCC 12V - 0 VDC
27 TCON_VCC 12V - 0 VDC


EVEN Pins:
2 DC_DIMMER - 0.007 VDC
4 PWM_DIMMER - 0.001 VDC
6 BLINKING (0.5 - 0.8 VDC range) fluctuating
8 BL_EAR - 0.039 VDC
10 GND - 0 VDC
12 GND - 0 VDC
14 REG 12V - 12.74 VDC
16 REG 12V - 12.74 VDC
18 REG 12V - 12.74 VDC
20 GND - 0 VDC
22 GND - 0 VDC
24 TCON_ON - 0 VDC
26 TCON_VCC 12V - 0 VDC
28 TCON_VCC 12V - 0 VDC

CAP 6524 Voltage across pins = 391 VDC
D6201 Voltage between gnd = 3.48 VDC
D6202 Voltage between gnd = 3.48 VDC

[dskall]

Re: Sony KD-65X750F - no lights/picture/sound

You seem to be getting no power on signal. Some board pictures and numbers would be helpful. You probably have a fuse on mainboard and voltages to check.

[brad2157]

Re: Sony KD-65X750F - no lights/picture/sound

You seem to be getting no power on signal. Some board pictures and numbers would be helpful. You probably have a fuse on mainboard and voltages to check.

I apologize for not including any pictures on my initial post.

Here are some pictures of the power and main boards. I took three pictures of the main board, one complete picture and two half pictures, so I could get better up close views.

[dskall]

Re: Sony KD-65X750F - no lights/picture/sound

I see plenty of fuse markings on mainboard but no fuses. You should have some voltages on the raised square inductors. First one having a 2R2 on it. They should be low 1.1, 1.8vdc to supply power to main processor. You should also have a red light from your ir port. looks like it is to left of hdmi ports with little door on it. Should be lit if board is powered up.

[alfatv]

Re: Sony KD-65X750F - no lights/picture/sound

Do know the history of this TV? How did it stop working?
Possibly it's bricked, you can try hard reset.
No status LED at all?

[brad2157]

Re: Sony KD-65X750F - no lights/picture/sound

I see plenty of fuse markings on mainboard but no fuses. You should have some voltages on the raised square inductors. First one having a 2R2 on it. They should be low 1.1, 1.8vdc to supply power to main processor. You should also have a red light from your ir port. looks like it is to left of hdmi ports with little door on it. Should be lit if board is powered up.

Thank you! I'll look at it tomorrow and see what I can find out voltage wise on those inductors. I'll also check for the red light as well.

[brad2157]

Re: Sony KD-65X750F - no lights/picture/sound

Do know the history of this TV? How did it stop working?
Possibly it's bricked, you can try hard reset.
No status LED at all?

I got the TV for free from the original owner. All he told is that it just quit working one day. I know that's really generic, but that's all I know. There's no status LED lit at all.

[brad2157]

Re: Sony KD-65X750F - no lights/picture/sound

I see plenty of fuse markings on mainboard but no fuses. You should have some voltages on the raised square inductors. First one having a 2R2 on it. They should be low 1.1, 1.8vdc to supply power to main processor. You should also have a red light from your ir port. looks like it is to left of hdmi ports with little door on it. Should be lit if board is powered up.

Inductor voltages on main board:

Measurements between inductor @ ground
2R2 = 3.34 VDC (above Sony BCX printed on board)
1RO = 1.04 VDC (to left of processor / white cover)
2R2 = 5.16 VDC (top right-hand side of board above HDMI connectors)

There is no red light on optical port to the left of the HDMI ports at any time.

[dskall]

Re: Sony KD-65X750F - no lights/picture/sound

Hard to diagnose mainbord over internet. Hard enough with it in front of you. There is a connector with grey and white wires. Should be going to ir and buttons on tv. They should have around 3.3v. If you find the one to power button or ir when you press buttons voltage should change if working.

[brad2157]

Re: Sony KD-65X750F - no lights/picture/sound

Hard to diagnose mainbord over internet. Hard enough with it in front of you. There is a connector with grey and white wires. Should be going to ir and buttons on tv. They should have around 3.3v. If you find the one to power button or ir when you press buttons voltage should change if working.

Thank you for all the input on this! I went ahead and bought a used main board to see if that fixes the issue. I'll report back once I get it in and installed. I may be able to further isolate checking between the good and bad boards.

[brad2157]

Re: Sony KD-65X750F - no lights/picture/sound

I installed the used replacement main board and that fixed my issue. I don’t have a lot of time to try to isolate the issue on the original board anytime soon, but I may try to do that at some point.