Powerbook LCD/Inverter Troubleshooting

Posted by: szsiddiq

Powerbook LCD/Inverter Troubleshooting - 02/21/07 06:16 AM

Last week my 12" powerbook's inverter board blew out while i was working on a mod.  While in use, the LCD backlight suddenly shut off, and the inverter board started smoking. The board itself has a small burnspot on it, that some how burnt through the insulation the board is wrapped in. i was able to get a new board, courtesy of MacMod and iFixIt, but that hasnt solved the problem.
Has the LCD's backlight burnt out or has the logic board's power supply for the lcd blown out?

Any thoughts?
Posted by: Kisin

Re: Powerbook LCD/Inverter Troubleshooting - 02/21/07 08:25 AM

check carefully with an inverter whether the backlight is gettin any juice, and go from there
Posted by: szsiddiq

Re: Powerbook LCD/Inverter Troubleshooting - 02/22/07 09:05 AM

if i manage to get in there with a multimeter, what sort of current/voltage shoud i look for out of the inverter?
Posted by: Waragainstsleep

Re: Powerbook LCD/Inverter Troubleshooting - 02/23/07 12:43 PM

The inverter outputs a fairly high AC supply. Its actually quite unusal for a backlight to fail entirely. Hate to be the bearer of bad news, but its more likely to be the power coming from the logic board. Its quite easy to short it out permanently. (This should be a DC supply, but don't measure it at the board end as this alone can short it out. Voice of experience.)

If the board isn't powering the inverter, its time for a new board. Or a new laptop.
Sorry.
Posted by: szsiddiq

Re: Powerbook LCD/Inverter Troubleshooting - 02/24/07 10:15 AM

Originally Posted By: "Waragainstsleep "

The inverter outputs a fairly high AC supply. Its actually quite unusal for a backlight to fail entirely. Hate to be the bearer of bad news, but its more likely to be the power coming from the logic board. Its quite easy to short it out permanently. (This should be a DC supply, but don't measure it at the board end as this alone can short it out. Voice of experience.)

If the board isn't powering the inverter, its time for a new board. Or a new laptop.
Sorry.


hmm, is it safe to measure the voltage at the inverter to lcd point?
Posted by: Waragainstsleep

Re: Powerbook LCD/Inverter Troubleshooting - 02/25/07 02:07 PM

Noy actually tried. I suspect you just need to find the place where the pins are furthest apart.
Posted by: szsiddiq

Re: Powerbook LCD/Inverter Troubleshooting - 02/27/07 02:19 PM

Assuming the voltage should be DC, i get a .02V reading from the inverter output plug.  And assuming that reading is accurate, its safe to assume that the logic board's lcd power source is blown. 

then again, to assume makes an ass out of u and me.
Posted by: Waragainstsleep

Re: Powerbook LCD/Inverter Troubleshooting - 02/28/07 01:48 AM

I measured the AC out from an inverter the other day. No harm done. I think pins on logic board connectors are just too close together.
Posted by: szsiddiq

Re: Powerbook LCD/Inverter Troubleshooting - 03/08/07 03:09 PM

Just got a new logic board today, and now all it working!
Thanks for all your help!