Z61t LCD Backlight Inverter Test Points and Specs

[jrjoyce]

Greetings,

We have a Z61t ThinkPad where the display suddenly went dark.  This occurred when the battery was about to die and the power adapter was plugged into it.  The LCD itself appears to be working, as images can be seen on it from some angles, the backlight just does not come on.  I haven't seen anything to suggest that there is a configuration setting where the backlight can just be switched off, so assume that this is a hardware problem, is that accurate?  While various things can cause this problem, it appears that the most common are either the CCFL had gone bad or the inverter that drives the CCFL has gone bad.

Considering the difference in price between these components, can anyone provide any information regarding any test points on the inverter and what the optimal values should be for them?   I would expect that it should be producing a constant high voltage, low current output, but would like to know the range values before diving into the unit.  Also, as it appears that there are a number of fuses on the motherboard that are rather sensitive to out of spec conditions, does anyone have any experience with the best type of meter to use for checking them?  I would assume that it would be best to use a fairly high impedence meter for this test, but am not sure what the designers of this board would have considered 'high'.

Any suggestions or observations you may have made while testing the inverter would be most welcome.

Thanks,

JJ

[ajkula66 Guru]

Welcome to the forum!

I doubt that anyone will have the specs that you're looking for handy...so here's my train of thoughts:

You can pick up an inverter on eBay for $20 or so.

If that fixes the problem, you're golden. If not...time for a new screen.

Good luck.

[Tsunade_Hime]

Consider replacing the inverter/LVDS cable first before LCD, but you need to replace with known good parts to rule out anything.

[richk]

If the screen had not previously had a red tinge at startup, it is most likely the inverter and not the bulb. A blown fuse on the motherboard can cause the same symptoms, but that is unlikely the way you describe the situation leading up to the failure. If I see this condition, I do the inverter first. Then I test the fuses before doing the LCD, unless I have a good working assembly to swap in for a test.