EU55JS9000T black screen and sound good

[nomoresonys]

Re: EU55JS9000T black screen and sound good

Another thing that's easy to try if those things your looking at check out ok, is take connector CN301 and CN801 off and try it, will be no wifi or sound of course. just wondering if that bit of less power required would make a difference, then would maybe have a better idea of where to look.

[nomoresonys]

Re: EU55JS9000T black screen and sound good

It's too bad that you don't have another tv to try that ocb on.

[nomoresonys]

Re: EU55JS9000T black screen and sound good

https://www.ebay.co.uk/p/12061435673

[totof]

Re: EU55JS9000T black screen and sound good

Sometimes it can be the components in a circuit that can make things seem shorted, like if there's a resistor in circuit across it, it may read short and be ok, that's why you get the best results off the board.

I agree with you.
This short circuit capacitor is suspicious but I don't know where the origin is. There are definitely voltages on all the inductors, however I don't know if they are all correct.

To check if there is an image I planned to disconnect the PWM signals from the TCON board to inject a voltage of 1V directly onto the backlight control board. What do you think about this test and should a DC voltage be injected?

[nomoresonys]

Re: EU55JS9000T black screen and sound good

Did you get a reading on that cap in ohm mode? test as in post #57.

[nomoresonys]

Re: EU55JS9000T black screen and sound good

I agree with you.
This short circuit capacitor is suspicious but I don't know where the origin is. There are definitely voltages on all the inductors, however I don't know if they are all correct.

To check if there is an image I planned to disconnect the PWM signals from the TCON board to inject a voltage of 1V directly onto the backlight control board. What do you think about this test and should a DC voltage be injected?

I'm not sure how that works.

[nomoresonys]

Re: EU55JS9000T black screen and sound good

I do see a backlight operation test in your training pdf from the first post.

[nomoresonys]

Re: EU55JS9000T black screen and sound good

Testing Backlights
1. Remove CN803 (Main to SMPS) and CN9003
(Main to Micro Dimming Board) to activate Back Lights.
Both connectors must be removed to light backlights.
2. Check each of the 16 circled components above in each
L and R quadrants for approx. 95VDC by connecting the p
lus lead of the multi meter to either side as shown on left (
BB9101) and negative meter lead to chassis ground.
3. If any read high (approx 160VDC) a string of LED
Backlights are open (defective panel). If a voltage is low,
remove the LED panel connector & test again. If it stays
low replace defective SMPS.

[nomoresonys]

Re: EU55JS9000T black screen and sound good

Above is from your training pdf, there's pictures there too.

[totof]

Re: EU55JS9000T black screen and sound good

Did you get a reading on that cap in ohm mode? test as in post #57.

OL in ohm mode on multimeter. No short cut.

I do see a backlight operation test in your training pdf from the first post.

Yes the backlighting works but it turns off immediately (<0.2 sec) as soon as the OCB cable is plugged in.
The P_DIM1..16 signals from TCON board falls to 0,36V, BL_ON is still good (4,7V)
The Tcon test works well (see post #22) but only when ocb is not connected

Testing Backlights
1. Remove CN803 (Main to SMPS) and CN9003
(Main to Micro Dimming Board) to activate Back Lights.
Both connectors must be removed to light backlights.
2. Check each of the 16 circled components above in each
L and R quadrants for approx. 95VDC by connecting the p
lus lead of the multi meter to either side as shown on left (
BB9101) and negative meter lead to chassis ground.
3. If any read high (approx 160VDC) a string of LED
Backlights are open (defective panel). If a voltage is low,
remove the LED panel connector & test again. If it stays
low replace defective SMPS.

OK, I will try this test

[totof]

Re: EU55JS9000T black screen and sound good

My backlighting control board is not exactly the same as that in the document on post #1, the connectors are the same but the components are different.
At the terminals of the 16 diodes I measure 59V on one side and 20V on the other with the reference on the chassis.

[nomoresonys]

Re: EU55JS9000T black screen and sound good

https://www.youtube.com/watch?v=ymvyxlWdEck


https://www.youtube.com/watch?v=1QigP2qkv0M

[nomoresonys]

Re: EU55JS9000T black screen and sound good

Why would a capacitor read OL?
If the capacitance value is within the measurement range, the multimeter will display the capacitor's value. It will display OL if a) the capacitance value is higher than the measurement range or b) the capacitor is faulty.

[nomoresonys]

Re: EU55JS9000T black screen and sound good

So if you are getting a reading, NOT OL on all your other capacitors, then that one is bad.

[Davi.p]

Re: EU55JS9000T black screen and sound good

It's total waste of time and riskful to test backlight, since in Screen test everything works then your defect is 100% in the couple OCB+main board (let's call it so...)

[nomoresonys]

Re: EU55JS9000T black screen and sound good

Well if you already did a backlight test that passed, don't try anything experimental, like you described.

[totof]

Re: EU55JS9000T black screen and sound good

Why would a capacitor read OL?
If the capacitance value is within the measurement range, the multimeter will display the capacitor's value. It will display OL if a) the capacitance value is higher than the measurement range or b) the capacitor is faulty.

I read OL for capacitor in ohm mode, in capacitance mode I read 1 microfarad.

It's total waste of time and riskful to test backlight, since in Screen test everything works then your defect is 100% in the couple OCB+main board (let's call it so...)

Yes I agree with you.

[nomoresonys]

Re: EU55JS9000T black screen and sound good

Now read, check the other similar capacitors in the area, leave them in circuit, DO they also show OL??

[totof]

Re: EU55JS9000T black screen and sound good

Now read, check the other similar capacitors in the area, leave them in circuit, DO they also show OL??

Last week-end I have checked all capacitors on the data lanes of the ocb cable and all are good (100 nF). I have checked this capacitors on main board side and on ocd side.

Attached photo of the OCB board to the connector to the motherboard

[nomoresonys]

Re: EU55JS9000T black screen and sound good

I don't like to but I give up, we seem to have a communication error.