Cross reference for B90N08

[dick_barton]

Re: Cross reference for B90N08

Can you take the voltage readings with everything connected and attempting to turn it out of standby and at the second red box marked

[ned1]

Re: Cross reference for B90N08

Here is the voltage measurements:
corner connector is same as before
5V 5V
5V 5V
G 0
G 0
ENA 0
ADJ 0
Connector that I missed previously to give readings is
PIN1 0
PIN2 0
PIN3 25V
PIN4 25V
PIN5 0
PIN6 0

[dick_barton]

Re: Cross reference for B90N08

Do you have a picture of the back of the set with all the boards to see the interconnections.

You could try taking ENA to +5V using a 1K resistor and see if the leds light up or at least check the voltages going to them.

Since it's a monitor it may not have ENA voltage unless it's plugged into a source but I'm not certain. Probably needs the ENA to switch on the OZxxxx chip to power the leds.

[ned1]

Re: Cross reference for B90N08

When I plug the power cord on it tries to light the LEDs , you can see a blink and it stays dark after it

[CapLeaker]

Re: Cross reference for B90N08

sounds like a bad LED.

If you have the main board connected to the PSU and the ENA pin stays 0 when you turned the TV on, then you have a main board problem as well.

[dick_barton]

Re: Cross reference for B90N08

sounds like a bad LED.

If you have the main board connected to the PSU and the ENA pin stays 0 when you turned the TV on, then you have a main board problem as well.

The led output connector is only at 25V so I think the OZxxx chip is not running but that could be because it's not enabled.

[ned1]

Re: Cross reference for B90N08

I will measure to enable voltage at the moment when I power it on, it may get 5V then goes to standby.

[ned1]

Re: Cross reference for B90N08

Correction, the ADJ pin is 2.9V ENA pin is always 0.

[ned1]

Re: Cross reference for B90N08

Here is the picture of how the boards and panel are connected

[dick_barton]

Re: Cross reference for B90N08

1. "Do you have a picture of the back of the set with all the boards to see the interconnections"

Photo's please


2. You could try taking ENA to +5V using a 1K resistor and see if the leds light up or at least check the voltages going to them.

Have you tried this and what was the result.


3. Since it's a monitor it may not have ENA voltage unless it's plugged into a source but I'm not certain. Probably needs the ENA to switch on the OZxxxx chip to power the leds.

Is this a PC monitor and does ENA go to 5V when connected to the PC.

[ned1]

Re: Cross reference for B90N08

Is the picture I sent earlier the one you are looking for

[dick_barton]

Re: Cross reference for B90N08

Sorry I missed that. There are cables at the top of the photo running to the right and off the photo and also cables at the bottom of the screen that go off to the unknown.

Edit
I'm trying to work out how everything is connected.

[ned1]

Re: Cross reference for B90N08

I am looking for 1k resistor then will do test. Few more closer pictures.

[ned1]

Re: Cross reference for B90N08

Main board connection

[ned1]

Re: Cross reference for B90N08

Hope this helps

[budm]

Re: Cross reference for B90N08

It looks like the RED/YELLOW/GREEN/BROWN/??? wires bundle is for the LED BACKLIGHTS but not 100 % sure since we cannot see the whole LCD panel.
When you force on the ENA pin, the connection going back to the LOGIC/MAIN board has to be disconnected otherwise the ENA line will be kept LOW by the LOGIC/MAIN board.
The resistor can be anything between 470~1000 Ohms.

It looks like it has 4 strings of LEDs.
https://www.badcaps.net/forum/attach...6&d=1472745624

[budm]

Re: Cross reference for B90N08

What is the DCV rating of the cap C2A (Filter cap for the boost converter output)?
What is the DCV on C110 (input Voltage to the boost converter)?

[ned1]

Re: Cross reference for B90N08

C2A cap is 100V 47uF. C110 is 50V 680uF.
The bundle of wires from power supply board that is disconnected on the end connects to the panel.

[budm]

Re: Cross reference for B90N08

OK, 25V input to the boost converter is about right, and since the boost converter is not ON so you will see the 25V at the LED b+ connector that feed the Anode of the LED's strings.
Once the ENA signal is present then you should see much higher B+ for the LED strings if the boost converter circuit is OK.

[ned1]

Re: Cross reference for B90N08

Can I remove power board take it with me to work and solder 1k resistor between 5v pin and ENA then measure other pins that were 0 on the power board.