RCA led65g55r120q power supply problem

[Electechj]

When backlight 5v signal is applied,tv shuts down and goes into protect mode. When 5v backlight signal is removed, tv stays on with image and sound.

[dskall]

Re: RCA led65g55r120q power supply problem

Need good clear straight on pictures of back of tv with cover off and each board.


Need voltages from connector that goes from power supply board to main board. Will need pin#- PIN DESCRIPTION -Pin voltage in standby-Pin voltage when pushing power button and picture of connector on power supply board.
Format:
Pin# - Pin Description - Pin Voltage standby - Pin voltage power on
1 - XXXXXXX - XXv - XXXv
2 - XXXXXXX - XXXv - XXXv
3 - XXXXXXX - XXXv - XXXv
4 - etc.

[Electechj]

[QUOTE=dskall;741874]Need good clear straight on pictures of back of tv with cover off and each board.

[Electechj]

Re: RCA led65g55r120q power supply problem

Power board - backlight 5v signal connected
Pin # 1. 24v , standby = 0v , power on = 24v then drops to 0v
Pin #2. 24v, standby = 0v,power on = 24v then drops to 0v
Pin #3 & #4 = gnd
Pin #5,#6 & #8 = 12v ,standby = 0v, power on = 12v then drops to 0v
Pin #7,#9,#10 & #11 = gnd
Pin #12,#13 & #14 = 5v, standby = 0v, power on = 5v then drops to 0v
Pin #15 = PS , standby = 0v, power on = 2.8v then drops to 0v
Pin #16 = 5vs ,standby = 5.1v ,power on = 4.9v then drops to 1v and then back to 5.1v
Pin #17 = ADJ , standby = 0v, power on = 4.8v then drops to 0v
Pin #18 = BK ,standby = 0v,power on = 1v then quick drop to 0v

[dskall]

Re: RCA led65g55r120q power supply problem

Pin #16 is your standby dropping to 1v?

[Electechj]

Re: RCA led65g55r120q power supply problem

Yes , this happens on shut down/protect mode. Then it goes back to 5.1v. Delay/dead time it's at 4.9v. Backlights flash on shut down.

[Electechj]

Re: RCA led65g55r120q power supply problem

Need to add there is no 24v hookup so no 24v supply line. Couldn't edit post , is the reason for this message

[budm]

Re: RCA led65g55r120q power supply problem

https://www.badcaps.net/forum/attach...4&d=1492918162
See that small lytics startup/running cap on the right side (STBY power supply section) right next (touching?) to the heatsink, check ESR/CAPACITANCE or replace it.
Also check ESR/CAPACITANCE the filter cap in the cold side of that STBY power supply also.

[Electechj]

Re: RCA led65g55r120q power supply problem

Thanks for your help . I did some test and found these voltages on the backlight/ADJ circuit . I found 1.5v on the backlight optocoupler PFC/cold side and .7v on the ADJ optocoupler . Hot side backlight optocoupler was 16.8v and ADJ hot side was .3v . Checked and changed the electrolytic on the ADJ optocoupler with no change.

[budm]

Re: RCA led65g55r120q power supply problem

The standby power supply should never drop in the first place, so until you get the standby power supply to be stable first then nothing else matter. When standby power supply drops to 1V then all the control signals will drop, same for the Voltage generated by the AUX winding of the standby power supply to run other SMPS IC for other power supply section. You need to put dummy load on the standby to see if it can handle the load or not.

[dskall]

Re: RCA led65g55r120q power supply problem

Can you get number of your controller chip on backside near small transformer. Looks like 8 pin ic.

[Electechj]

Re: RCA led65g55r120q power supply problem

I will do a load test tonight had to work late today.

The pfc # is ap4310am

[Electechj]

Re: RCA led65g55r120q power supply problem

Did a 5v load test with BK connected and disconnected, on and off condition. At first the florescent light stayed on then when power on into shut down light went off then back on then back off then back on .......
It then went on and off in stby . Looks like a bad stby supply.

[Electechj]

Re: RCA led65g55r120q power supply problem

Turns out the problem was a regulator and a blown L.E.D . Voltage flash on led output was 82v and 34v (regulator). After replacing regulators voltage read 283v and 147v. The 283v told me no load was connected ,therefore burnt L.E.D.