55EC930V Help please

[R_J]

Re: 55EC930V Help please

There is no need to take the relay apart. also if there was a load in the circuits that are supplied by F101 and F102 the relay would turn on and the fuses would blow.
I believe he is measuring 120vac from chassis ground to the fuse, that is why he is measuring 120vac

[jram]

Re: 55EC930V Help please

Ok, Firstly, thank you both for your help


@R_J
My initial voltages were erroneous vs chassis - the correct voltages are 331 vs C621 (-ve)

I measured the following voltages vs J50 with no jumper then with jumper P1 (verified by coloured wire and triangle on the board) to P3 the next pin up.

C507 17.0 0-2V
C503 16.5 6.6-6.7
C504 15.3 13.6-14

I don't have the experience to tell which cap is bad (no schematic) but I'm guessing its C507?

[R_J]

Re: 55EC930V Help please

You are getting close to solving this problem.

The voltage on C507 should not drop to 0 when the power supply is turned on, I suspect you could have a short on Q501 emitter to hot ground. (The transistor will be ok)
Check that ZD502 is not shorted.
Check the resistance across the relay coil, There is a small diode and a capacitor across the coil also. The coil, diode or small cap could be shorted.

When Q501 is turned on by the opto, it must be switching the 17 volts to hot ground. This also reduces the feedback feedback voltage in the standby circuit and that is why the standby 3.3 volts also drops.
The voltage should be about 12v on Q501 emitter to turn on the relay, the voltage is not there son no relay click and without the relay turning ON, you will not have any of the other power supply voltages.

[jram]

Re: 55EC930V Help please

You are getting close to solving this problem.

The voltage on C507 should not drop to 0 when the power supply is turned on, I suspect you could have a short on Q501 emitter to hot ground. (The transistor will be ok)
Check that ZD502 is not shorted.
Check the resistance across the relay coil, There is a small diode and a capacitor across the coil also. The coil, diode or small cap could be shorted.

When Q501 is turned on by the opto, it must be switching the 17 volts to hot ground. This also reduces the feedback feedback voltage in the standby circuit and that is why the standby 3.3 volts also drops.
The voltage should be about 12v on Q501 emitter to turn on the relay, the voltage is not there son no relay click and without the relay turning ON, you will not have any of the other power supply voltages.

Thanks R_J - I see where we are going with this.

OK - ZD502 is not shorted.
Coil resistance 49.7 ohms - neither the diode or cap shorted (i.e. resistance across each consistent at 49.7).

I checked the Q501 voltages with the jumper in and out - 17V collector and Zero B/E - no Jumper. With Jumper 2V Collector and 500mV B/E so its turning on a little but not enough.

I checked further down the chain C509 has a resistance of only 5 Ohms. I'm going to replace it and see what happens

[R_J]

Re: 55EC930V Help please

Well either the voltage at the collector can't supply enough current to turn on the relay, or something is drawing too much current. Check R501 and R502, they could have changed value?
Even if the base voltage is not high enough, the voltage on the collector should not drop.
This transistor acts like a switch but also as a regulator that supplies the voltage to the relay but also supplies the VCC for the pfc ic. The zener diode on its base sets the regulators output voltage, likely 12v.

[jram]

Re: 55EC930V Help please

C509 replaced - CLICK!

Now to start checking voltages...

With only Pins 1 and 3 jumpered, 12V and 24 V present on correct pins of P102 - working through the rest of the troubleshooting guide - will update

[R_J]

Re: 55EC930V Help please

Ok, so C509 was measuring 5Ω out of circuit? Check Q501 emitter voltage.

[Diah]

Re: 55EC930V Help please

good job R_J

OP .. you need to discharge the PSU before plug the MB back and T-CON after you are sure 12 24 v. stable

[jram]

Re: 55EC930V Help please

Good job guys. Now we are getting closer to the original problem.

I can't check the 24V power delivery since I don't have a bulb!

So I have connected the T-CON and also the main board and applied power. The relay clicks on and after 10 seconds or so, clicks off.
If I disconnect the main board and replace the jumpers and apply power, the relay clicks on and stays on. The screen is mostly black with broken white horizontal lines the full width of the screen in a band that is about 1/4 up from the bottom and 1/4 screen height wide. I believe this to be the original symptom (although the description given did not give me confidence.

[R_J]

Re: 55EC930V Help please

Do you have your +12v and +24 volts on P201? Does the +24v come up on P202, I suspect the power supply is now fixed and you have other problems on one of the other boards.

[Diah]

Re: 55EC930V Help please

bulb test he refer to screen T-CON test...

never do the jumpers test again keep it connected to MB and T-CON

you may have the second click off goes to stand by.. so turn it on again by power on TV set or with RC

[jram]

Re: 55EC930V Help please

OK - With T-Con and main board connected, it clicks on and then off after 3 seconds. Switching on at the power button has the same result. The voltages, however stabilise at 12 and 24V and P201 and P202 while its on.

[Diah]

Re: 55EC930V Help please

OK - With T-Con and main board connected, it clicks on and then off after 3 seconds. Switching on at the power button has the same result. The voltages, however stabilise at 12 and 24V and P201 and P202 while its on.

disconnect the LVDS cable from MB side and then turn on.. will stay on ?

[nomoresonys]

Re: 55EC930V Help please

Check P201 again, see if pwr-on and drv-on have correct voltage and if they change state after power on.

[R_J]

Re: 55EC930V Help please

I see the lightbulb test is to provide a load to the +24v and eliminate the chance of the t-con or panel shutting the tv down. If you don't have the bulb to place across the +24v I don't know how else you can eliminate the t-con/panel

[jram]

Re: 55EC930V Help please

Sorry for my absence guys - Had to go away for 2 weeks last night. Will hopefully conclude this epic after the 26th! Thanks for all your help - P.S. I'll get a bulb by then

[jram]

Re: 55EC930V Help please

I'm back!

I started again. Doing test 1, P2300 voltages are good apart from Pin 4 which is zero volts. I see no mention of the significance of pin 4 in the SMPS PDF so I thought I'd ask for guidance please

[Davi.p]

Re: 55EC930V Help please

Deleted..

[Davi.p]

Re: 55EC930V Help please

ONE YEAR later?? well... it's time to move to mainboard.. psu is ok..
i think i see a standby microcontroller , maybe the memory polluted, are you familiar with programming of theese chips? have you got a programmer?

[jram]

Re: 55EC930V Help please

ONE YEAR later?? well... it's time to move to mainboard.. psu is ok..
i think i see a standby microcontroller , maybe the memory polluted, are you familiar with programming of theese chips? have you got a programmer?

I have some programmers. Depends on what processor.