Expected Signal Voltages on backlight inverter?

I think my backlight inverter has blown in my PowerBook G4 12 inch DVI.. The part has 820-1567-A stamped on it but it is listed in the service manual as a 922-6247.
I've buzzed out the logic board and the inverter with my scope and have now hit the net hoping to find someone who knows what the nominal voltages for the inverters lines actually are so I can reference the specs to my diagnosis... I don't really follow Apples approach of replace this, oops it popped, replace this and this till the unit works... Going via their service manual & Especially on my own gear!!
If you know the voltages - I would love to compare my units levels to the info you have... ANYONE OUT THERE???
My logic board to inverter socket has:
1 - RED +0.7V AT ZERO BRIGHTNESS AND +0.7V ALSO AT 100%(BUCKS V+ REFERENCE??)
2 - BLACK 0V REF GROUND
3 - YELLOW +5V SUPPLY
4- GREEN 0V AT ZERO BRIGHTNESS AND +3.2V AT 100% BRIGHTNESS (CONTROL LINE).
Going from those results my LOGIC BOARD is A.O.K I THINK!!
Inverter has:
0 - 2V entering the transformer and only 4.9-5.5VAC exiting it - I would have expected 180 - 300 VAC...
The coil measures 628 Ohm to ground on the HV side and 2 Ohms exists on the primary coil <- The coil could be OK or dead (need to refer to data or a good inverter...)
Output Transistors look OK - have not tested them though...
Has anyone else put a meter or scope across their inverter?? Your results would be much appreciated!!
e

SOLVED!! The backlight is working again!!
All the lines had the correct voltage levels and signaling apart from the RED line. It was not a reference but a +12 volt supply. The thermal fuse on the logic board was blown so I replaced it, the inverter gets power and we have light!
The fault was caused (I think) by:
a lag in the OS/Firmware - bottleneck somewhere - when the brightness was adjusted during the lockup, the keyboard commands were cached and created a dump of hardware conditions. The inverter in turn tried to adjust itself once the bottleneck cleared - all within an instant - demanding a few seconds of swinging current that spiked the thermal fuse into its afterlife... The lesson is - press the button once and not 500 times!!

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Dear all,
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CPUT wrote:
I am new in Labview programing and i plan to capture AC Voltagel(Not DC voltage).
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look here http://www.fonerbooks.com/laptop14.htm
and here http://www.lcdpart.com/Products/ms26361.html
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Plrease reply ASAP

The inverter regualtes the power to the back light, i had macbook 2008 inverter break on me and attempted the fix myself. £10 ($15) for the inverter on ebay and about an hour of my time. The reason its a tricky fix is because the inverter is in the hinge of the screen so the whole screen needs to be removed! as i put it back together i was silently praying that i had put everything back right!
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This question was solved.
View Solution.

Sikat_08,
You are looking for a replacement backlight, is that correct? I will try to help you.
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Please respond back at your earliest convenience.
Thanks
Clicking the White Kudos star on the left is a way to say Thanks!
Clicking the 'Accept as Solution' button is a way to let others know which steps helped solve the problem!

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I think this is what you need: http://www.pbparts.com/shop/a123i.html
It bothers me, that I have not been able to find confirmation that the above part is different from the one used in my (1GHz) 12" Powerbook - http://www.pbparts.com/shop/a12di.html
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Is this voltage too high??

Alright..classic 14" Ibook no backlight problem.
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What do you think? Is 16 ok? Should I order a bulb and try that next or would I be wasting my money?
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OK Rob,
Here's the troubleshooting from the 14.1 1.42 Service Manual:
"Display
No display, or dim display, but computer appears to operate correctly (if dim,
display shows startup icon and/or desktop)
1. Remove any connected peripherals.
2. Try known-good power outlet, power adapter and power cord.
3. Press F2 (with the fn key pressed and not pressed) to increase the screen brightness setting.
4. Reboot the computer—hold down the Control and Command keys and press the
Power button, or press and hold the Power button for 5 to 10 seconds to shut down the computer, then press the Power button to restart.
5. Reset the power manager by pressing the key combination Control-Option-Shiftpower.
Warning: Make sure you do not hold down the "fn" key when resetting the
power manager.
Warning: Resetting the power manager means you will also need to reset the
date and time (using the Date & Time control panel)."
6. Reset PRAM (Press the power button, then hold down the Option-Command-P-R
keys until you hear the startup chime at least one additional time after the initial
startup chime).
7. Connect an external display, and check for video on external display.
• If video is fine on external display, troubleshoot LCD panel and verify cable
connections to inverter and LCD.
• If video symptom is same on external display, replace logic board."
That would imply a GPU error
"8. Verify backlight cable and LVDS cable connections are seated properly and that the
cables are not damaged (refer to display assembly replacement instructions)."
I flex the cables near the hinge point to do this check. Especially pushing them into compression (to make any broken connections)
"9. Replace LCD panel.
10. Verify cable connections and check cables around the hinges for damage.
11. Replace logic board."
1 black and 1 grey wire which I believe are the airport antenna, and a black wire for the microphone.
Also from the Manual:
"From the bottom of the bezel brace, note the routing of the black and gray antenna cables."
So those sound like the Bluetooth and Wireless antenna cables.
The LVDS cable is bundled with the mike (black) cable and is fat and gray.
Richard
Message was edited by: spudnuty

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Hi,
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Attachments:
Save data with control signal.vi ‏187 KB

siva0182 wrote:
Find attached the picture of the vi where I tried to put in timers.one in each of the frame and at the end added one more frame just to measure the time elapsed .
The last frame and the frame with sourcemeter measurment show adifference of about 140 msec.
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But surprisingly I tried displaying the actual timer value at the start and at the start of sourcemeter read function ..but the display of both indicators is almost equal with little difference of only 10 msec.????? I'm not sure which of the several timers you are referring to here. What is the value going into the wait function between the VISA write and the Keithly VI?
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Expected Signal Voltages on backlight inverter?

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