HP no backlight

[budm]

Re: HP no backlight

OK, after looking through my HP pictures collections, this HP VS17 uses the same power supply/inverter board as VS19/D.
Here is the service manual, the sch seems to match your board. It also has good explanation how it works.

[retiredcaps]

Re: HP no backlight

VDDA, in other OZ9 datasheets, is typically 5V DC. If it is low, then it could be that the OZ9 pwm is some sort of protection mode (over voltage, open lamp protection).

I suggest measuring the secondary windings (in red and yellow) on the inverter transformers to see if open is open. Post your resistance measures for both colors.

[davg]

Re: HP no backlight

According to that drawing It would appear I should have 5v on pin 7 and I am recording 1.9? or is something else in that circuit effecting that voltage?

[budm]

Re: HP no backlight

Did anyone find the place to download the spec sheet?

[jetadm123]

Re: HP no backlight

Thanks retiredcaps. It does shed a little light on the subject by identifying which pin is which. Only problem is that we still don't what the minimum voltage(s) are required to make the OZ9930 run correctly.

[retiredcaps]

Re: HP no backlight

I'm in a holding pattern right now because I can't seem to locate a data sheet for the OZ9930.

https://www.badcaps.net/forum/showthread.php?t=8907

may help?

[davg]

Re: HP no backlight

I have searched and can't seem to find one either. Closes I could find was OZ998 Thanks

[jetadm123]

Re: HP no backlight

I'm in a holding pattern right now because I can't seem to locate a data sheet for the OZ9930.

[davg]

Re: HP no backlight

The markings on (I101) is Line 1- OZ9930D, Line 2- 43279731G Line 3- 0505A The voltage readings are as follows: With the indicator mark north and pin 1 immediate left and pin 8 immediate right Pin 1- 2.4v pin 2- 0.08v pin 3- 0.01v pin 4- 0.01v pin 5- 0.01 pin 6- 3.8 pin 7- 1.9v pin 8- 0.05v

[jetadm123]

Re: HP no backlight

Doesn't look like anything is shorted. Looks like we will have to move on to the ccfl controller, I101. Fortunately, it's only 8-pin. Measure the voltage at each pin. What's the part number of I101? Note: I have to run some errands and will be gone several hours.

[davg]

Re: HP no backlight

Q106 reading EB 51.7 k BC 151k EC 99k both ways Q107 EB 99.4k BC 16m EC 16m reversed EB 99.4k BC 16.5M EC 16m (meter set to auto)

[jetadm123]

Re: HP no backlight

Good. At least we know those transistors have access to power to perform their switching actions.

In the top middle of your power supply photo:

With power off and monitor unplugged, try checking transistors Q106 and Q107.

With your meter set to 200 ohms, place your meter probes across:

E-B
B-C
E-C

Reverse your leads and perform the same checks again.

You may have to set your meter to a higher resistance setting to see a valid reading.

[davg]

Re: HP no backlight

Thanks jetadm123 Pin 3 (S1) Q104-Q105 both read 26.2v Black lead on ground screw red lead on pin 3, connected to running PC

[jetadm123]

Re: HP no backlight

Ah, I misunderstood your initial voltage readings for on/off. Looks like the main board is sending the correct 3.24V to turn on the backlights. Disregard my initial comments regarding I308.

Going back to Q104 and Q105. What voltage readings are you getting when you measure pin 3 (S1) on Q104 and Q105?

[davg]

Re: HP no backlight

Thanks budm when connected to running pc I am reading 2.32v 3.24v 5.12v 5.13v 0v 0v 0v 12.24v on that 8 pin connector marked BRI ON-OFF, 5V, 5V, GRN, GRN, GRN, 12V. When the light turns amber the 3.24v drops to 0v?

[budm]

Re: HP no backlight

So when the LED turns blue with connection to running PC, do you now get >3VDC at the ON/OFF PIN? If you do, then we need to go back and troubleshoot the inverter circuits.

[davg]

Re: HP no backlight

Thanks jetadm123 The best I can tell the markings on that I308 is ARNQ4 but it is so small it's a job to tell.?

[jetadm123]

Re: HP no backlight

Your voltage regulator readings look good. Here's what I think the problem is:

On your photo of the logic board, what is the part number for I308? It's the 3 terminal device right above the 10-wire wiring harness. If it's something like MAX809/810, then it's a reset controller. If yes, with power off, use your soldering iron to lift the VCC and RESET pins off the circuit board. Power up the monitor to see if you get an image. Note: failure of this controller has caused the same problem on various acer models.

[davg]

Re: HP no backlight

I noticed that the caps on this board are CapXon even though they look OK could these cause the problem?

[davg]

Re: HP no backlight

The readings on the two regulators I304 and I305 are as follows:
I304
AIC line 1
1084-33PM line 2
328GC line 3
pin #1- 0V
pin#2- 3.29v
pin#3- 4.9v

I305
1117 line#1
-18PE line#2
91OCT line#3
pin #1 - 0v
pin#2 - 1.79v
pin#3 - 3.29
pins numbered left to right with long pad north