HP22 2sec to black CCFL to LED conversion

[steves7839]

I installed two LED strips with the included driver into this 22" monitor. The screen is nice and bright now. But no menu or sound.

Before surgery the monitor showed a welcome "no source connected" screen for about two seconds. Most of the display around the welcome screen was dark. It then powered off the backlight.

If the display is now all white, does that mean no video signal is getting to the LCD panel? Or maybe I just put the polarizer, glass plate and LCD panel back together in the wrong order.

Suggestions?

The model number is W22; the panel is Chi Mei M220Z1-L01

[boyebaran]

Re: HP22 2sec to black CCFL to LED conversion

hi
you must disable protecting by controler ic .
please upload clear picture from ic or send part number.
protect means when one of component have problem(ccfl-high voltage and.....)ccfl controller ic shutdown power supply for avoid further damage.
you disconnected ccfl from board and ic not sense ccfl and gone to protect

[budm]

Re: HP22 2sec to black CCFL to LED conversion

Did you verify that LVDS cable at the LCD PANEL is secure back in properly when you put the unit back together? You may also have to verify that you do have either 5V or 12V at the smd fuse on the T-CON on the LCD panel assembly or not.

[steves7839]

Re: HP22 2sec to black CCFL to LED conversion

Thanks for the replies, guys!

Here's a picture of the main board; is this the controller IC you mentioned? Or is it on the power supply near the inverter section?

BudM, the T-Con appears to be incorporated in the circuit board attached to the LCD panel. There's no twisted-pair LVDS cable, just a flat cable to that board from the main board.

Also, I forced the backlight on using a 3.2V from the main board, but have not connected the dimmer line to the new LED driver board. I guess that means no brightness control.

[budm]

Re: HP22 2sec to black CCFL to LED conversion

I know that the T-CON is integrated to the LCD panel assembly, that flat ribbon cable is the LVDS cable which also provide either 5V or 12V to run the T-CON board and there is connector on that integrated T-CON board. BTW: LVDS cable does not have to be twisted pair, just about all monitor and TV use flat cable these days.
There is no error feedback signal used in this monitor to tell the logic board to go into shutdown if the backlight circuit detects the error, so it at this point the inverter circuit does not matter any more and the power going to the inverter section should be disconnected.
So do you have 5V or 12V at the T-CON or not?

[boyebaran]

Re: HP22 2sec to black CCFL to LED conversion

hi
you must disable protecting by controler ic .
please upload clear picture from ic or send part number.
protect means when one of component have problem(ccfl-high voltage and.....)ccfl controller ic shutdown power supply for avoid further damage.
you disconnected ccfl from board and ic not sense ccfl and gone to protect

ic placed under inverter board.

[Dumah Brazorf]

Re: HP22 2sec to black CCFL to LED conversion

Isn't backlight circuit independent from the image circuit?
I mean, usually if backlight shuts off you can see the image on the screen anyway using a flash light.
So probably the lcd is dead.
Where did you hook the power for leds?

[budm]

Re: HP22 2sec to black CCFL to LED conversion

Isn't backlight circuit independent from the image circuit?
I mean, usually if backlight shuts off you can see the image on the screen anyway using a flash light.
So probably the lcd is dead.
Where did you hook the power for leds?

That is correct! That is what I am trying to get through, there is no feedback from the backlights circuit to tell the main board to go into shutdown, that is why you can still see image on the screen using other light source when the backlights are not working.

[steves7839]

Re: HP22 2sec to black CCFL to LED conversion

In the photo of the LVDS connector, the pin closest to U202 has 5.1V for the first minute or so. It then goes to 0 as the monitor's power LED goes from green to amber. There is no picture, even by flashlight.

In the other photo there is a solder blob next to C211. I don't remember seeing it there at first inspection. I soldered the wire for the LED backlight power to the open pad for U202 and jumpered from CN201-12 for the BL enable wire.
I will have to disassemble to check the voltage at the other end of the ribbon cable, so will do that tomorrow.

[Dumah Brazorf]

Re: HP22 2sec to black CCFL to LED conversion

So are you powering that leds @5V? Aren't these kits work with 10V to 30V?
I don't think 5V line is beefy enough to power everything. You should power leds from the same line that serves the ccfl inverters.

[Andrew F. Ali]

Re: HP22 2sec to black CCFL to LED conversion

Most likely it would be 12V used to supply the CCFL circuit. That 12V MUST be disconnected from the CCFL circuit. That is the supply that should be used to power the LED Driver Bd. Also, the BL ON/OFF and DIM control MUST be connected to the LED Driver Bd. and taken from the Main Bd. or where the CCFL circuitry was getting those signals. Short cuts don't work in these cases.

[steves7839]

Re: HP22 2sec to black CCFL to LED conversion

The LED power board in the kit accepts 10-30VDC. I am powering it with 12V from the main board and using 3.4V for enable. I don’t yet know where to connect the “dim” input on the LED power board.

[momaka]

Re: HP22 2sec to black CCFL to LED conversion

In the photo of the LVDS connector, the pin closest to U202 has 5.1V for the first minute or so. It then goes to 0 as the monitor's power LED goes from green to amber. There is no picture, even by flashlight.

That appears normal. The power going to the T-con board should be OFF when the monitor's LED turns amber. But, if you still see a white image with the monitor's LED being green, then that means either the T-con is not getting proper signals from the logic board (due to dirty and/or misaligned LVDS cable) or due to bad inverter supplie(s) on the T-con board (though, I am not sure how you changing the CCFLs for LEDs would damage the T-con board's power supplies, so try re-seating the LVDS cable a few times and make sure its contacts are clean).

[Dumah Brazorf]

Re: HP22 2sec to black CCFL to LED conversion

Check the 12V when on.
Disconnect temporarily the new backlight and check with a flashlight if there is image.

[steves7839]

Re: HP22 2sec to black CCFL to LED conversion

It's fixed. Once I reopened the panel I found the LVDS ribbon cable loose. I also connected BL Enable to the inverter enable signal.
Since I had no input connected, the display went dark and the unit's power LED went amber after a minute, normal behavior.
Thanks for the suggestions!

[momaka]

Re: HP22 2sec to black CCFL to LED conversion

Good to hear you got it working!

[budm]

Re: HP22 2sec to black CCFL to LED conversion

Glad to hear, as suggested in post #3 for what to check.