Aspire 6530G - no backlight!

[Dan81]

As the title says, I have a 6530G here (that has been recased by myself into a near-pristine 6930G casing) will power on just fine.

The issue with it is that the backlight will not come on at all. Using a flashlight, I can see the laptop booting into Windows fine, and I do have external (HDMI) output.

First off, a few specs:

AMD Turion Ultra ZM-80 2.1GHz
2GB DDR2 (667 I think)
ATI Radeon Mobility HD4650 1GB - tested fine on another Acer (model 5520G, w/ MXM slot)
Hitachi-LG GT30N

Anyways, I have tested both the display and the inverter, and checked motherboard too.

Results:

-display works fine - tested on an Acer Aspire 5536G - backlight lights up.
-tested inverter - I have the main 19V and ADJUST voltage, but no ENABLE voltage.
-tested motherboard components responsible for the ENABLE signal - all tested up fine.
-tested EACH inverter SMD component - all came up fine.

Anything else I should try? I am at a loss at what else to try.

Again, the GPU is working fine and so is the LCD itself (Samsung LTN160AT01), and the inverter seems to do its job (as I have read 19v straight from the pin on the inverter PCB) but I don't have any slight hint of the ENABLE signal on the inverter.

Other useful data:

MB model: Quanta ZK3 Rev:E
Inverter model: Sumida IV10117T/C4-E-LF

[Techtiger]

Re: Aspire 6530G - no backlight!

If CN3 is your LVDS Connector check pin 10 1 5 2 voltage

[Dan81]

Re: Aspire 6530G - no backlight!

If CN3 is your LVDS Connector check pin 10 1 5 2 voltage

Yes, CN3 is LVDS.

Pin 1: 10V
Pin 2: 0V
Pin 5: 3.3V
Pin10: 1.16V

[Techtiger]

Re: Aspire 6530G - no backlight!

Yes, CN3 is LVDS.

Pin 1: 10V
Pin 2: 0V
Pin 5: 3.3V
Pin10: 1.16V

Now check U4 IC all pins expect 2/5 with power and with out power with the help of the multimeter resistance to ground all pins expect 2/5

[Dan81]

Re: Aspire 6530G - no backlight!

Now check U4 IC all pins expect 2/5 with power and with out power with the help of the multimeter resistance to ground all pins expect 2/5

Okay, here are the readings, meter set to 2k for 1 and 3, meter set to to 200ohms for 6 and 4.

No power:

Pin1: 1.490kOhm
Pin3: 1.274kOhm
Pin6: 5Ohm
Pin4: 5Ohm

With power applied I get infinite on all pins, and that's with the meter set and tested on each setting - 2k,20k,200k and even 2M.

I used one of the screws for the left hinge as GND reference.

[Techtiger]

Re: Aspire 6530G - no backlight!

Okay, here are the readings, meter set to 2k for 1 and 3, meter set to to 200ohms for 6 and 4.

No power:

Pin1: 1.490kOhm
Pin3: 1.274kOhm
Pin6: 5Ohm
Pin4: 5Ohm

With power applied I get infinite on all pins, and that's with the meter set and tested on each setting - 2k,20k,200k and even 2M.

I used one of the screws for the left hinge as GND reference.

Put the meter to 20V and test again Voltage on all pins of U4

[Dan81]

Re: Aspire 6530G - no backlight!

Put the meter to 20V and test again Voltage on all pins of U4

U4

Pin1:3.21V
Pin3:3.19V
Pin6:3.26V
Pin4:3.28V

[Techtiger]

Re: Aspire 6530G - no backlight!

Pin 1 is have 3V but the CN3 pin 2 0V check the resistor R22 both sides for Voltage, The screen must be connected to the motherboard when you test

[Dan81]

Re: Aspire 6530G - no backlight!

Pin 1 is have 3V but the CN3 pin 2 0V check the resistor R22 both sides for Voltage, The screen must be connected to the motherboard when you test

3.20V on both sides.

[Techtiger]

Re: Aspire 6530G - no backlight!

In Post#3 you have written 0V on pin 2 CN3! So now you have Voltage on pin 2 of CN3

[Dan81]

Re: Aspire 6530G - no backlight!

Yeah, I now figured out why I had 0V first time and have 3.2V. The first time I tried to measure pin2 I had to remove the LVDS cable to have access to it. Dumb move from my part.

However, how do I check pin10 now? I successfully found out I have 9V on CN3 pins 1 and 3 (these are the main power to the inverter), 3.20V on pin 2.

L.E: I managed to measure pin10 through the pads of unpopulated R175. 1.68V measured.

[Techtiger]

Re: Aspire 6530G - no backlight!

Now test Pin 15 BL_ON and Pin5 +3V

[Techtiger]

Re: Aspire 6530G - no backlight!

Yeah, I now figured out why I had 0V first time and have 3.2V. The first time I tried to measure pin2 I had to remove the LVDS cable to have access to it. Dumb move from my part.

However, how do I check pin10 now? I successfully found out I have 9V on CN3 pins 1 and 3 (these are the main power to the inverter), 3.20V on pin 2.

L.E: I managed to measure pin10 through the pads of unpopulated R175. 1.68V measured.

Now test Pin 15 BL_ON and Pin5 +3V, For the Main power 10V is for Battery not for the adapter (+19V) leave it for the moment

[Dan81]

Re: Aspire 6530G - no backlight!

Now test Pin 15 BL_ON and Pin5 +3V

Pin5: 3.3V
Pin 15: 0.54V

[Techtiger]

Re: Aspire 6530G - no backlight!

Pin5: 3.3V
Pin 15: 0.54V

This is your Backlight Control circuit check all voltage , pin 15 Voltage should be 3V-3.3V

[Dan81]

Re: Aspire 6530G - no backlight!

This is your Backlight Control circuit check all voltage , pin 15 Voltage should be 3V-3.3V

R36: 3.24V
R37: 3.24V (both sides)
R35: 3.24V only on one side
R32: 3.27V only on one side
R34: 3.27V on one side, 0.53V on the other
Q8: no voltage on any pins
Q7: 3.22V on gate
Q5: 3.27V on Drain and Source
Q4: 0.51V on Drain, nothing on the others
D2: 0.51V on one side, 0V on the other
Pin 15 still sits at 0.51V.

[Dan81]

Re: Aspire 6530G - no backlight!

A photo with the voltages.

At this point I am deciding whether to get another motherboard (a ZK2 this time, at least to put one of my T9400s to a good use) or just rig up a bunch of slim 5v LED strips behind the LCD.

[Techtiger]

Re: Aspire 6530G - no backlight!

A photo with the voltages.

At this point I am deciding whether to get another motherboard (a ZK2 this time, at least to put one of my T9400s to a good use) or just rig up a bunch of slim 5v LED strips behind the LCD.

Any Other member could help why BL_ON 0.53V?

[ktmmotocross]

Re: Aspire 6530G - no backlight!

no without detailed resistance measuring. i would check that LID signal

post full schematic

please wrote your reading for every pin of that mosfets in red color to picture.

u must have BL# grounded by Q7/gate is high/ so it not grounded by next mosfet/gate is low/ BL_ON signal.

[Dan81]

Re: Aspire 6530G - no backlight!

no without detailed resistance measuring. i would check that LID signal

post full schematic

please wrote your reading for every pin of that mosfets in red color to picture.

u must have BL# grounded by Q7/gate is high/ so it not grounded by next mosfet/gate is low/ BL_ON signal.

So if Q7 gate is grounded this enables the BL_ON signal?