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2 - Thinkpad A30p - Swap LCD and backlight not working on 2nd???

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larrystotler
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2 - Thinkpad A30p - Swap LCD and backlight not working on 2nd???

#1 Post by larrystotler » Thu Aug 31, 2017 4:53 pm

I have 2 Thinkpad A30p systems. the first was a complete unit that I've been having issues working properly with my dock. The 2nd was a base with a motherboard in it that worked fine with my dock(I thought it had a bios password, but it didn't).

When I swap the LCD to the 2nd unit, there is no backlight. When I put it back on the 1st, the backlight is fine........

I'm at a loss. I tired unhooking the CMOS battery from the 2nd and it didn't make a difference. The 2nd one shows video on the LCD and on an external monitor as well.

So, if the inverter is powering the LCD on the 1st, why is it not on the second. The ONLY difference I can find between the 2 motherboards is that the 1st says it is FRU 93p3530 and the 2nd shows FRU 26p8286. The 26p8286 is listed in the Hardware maintenance manual, but the 93p3530 is not. A google search does show it's an A30p board tho.

The panel is the UXGA. There is only the main connector on the motherboard and it doesn't appear damaged. I did see something about how one of the A30 cables had a reversed pinout on the inverter or something. I do have the lid from the 2nd unit. Should I try swapping the cables?

Any ideas? Thanx

Thinkpad4by3
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Re: 2 - Thinkpad A30p - Swap LCD and backlight not working on 2nd???

#2 Post by Thinkpad4by3 » Thu Aug 31, 2017 5:05 pm

Inverters die, they arent indestructible. 16 years of pumping thousands of volts into a CCFL bulb, the circuit sometimes gives up the ghost. Now if you plugged in another CCFL lamp of another IPS display, we could have a little problem.
Thinkpad4by3's Law of the Universe.

The efficiency of two screens equally sized with equal numbers if pixels are equal. The time spent by a 4:3 user complaining about 16:9 is proportional to the inefficiency working with a 16:9 display, therefore the amount of useful work extracted is equal.

larrystotler
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Re: 2 - Thinkpad A30p - Swap LCD and backlight not working on 2nd???

#3 Post by larrystotler » Thu Aug 31, 2017 5:17 pm

Thinkpad4by3 wrote:
Thu Aug 31, 2017 5:05 pm
Inverters die, they arent indestructible. 16 years of pumping thousands of volts into a CCFL bulb, the circuit sometimes gives up the ghost. Now if you plugged in another CCFL lamp of another IPS display, we could have a little problem.
I can't see how it's the inverter since the Display works fine on one motherboard but not the other.

Thinkpad4by3
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Re: 2 - Thinkpad A30p - Swap LCD and backlight not working on 2nd???

#4 Post by Thinkpad4by3 » Thu Aug 31, 2017 5:32 pm

Ah, your talking the entire display assembly. My bad. By display, I thoughr you meant the bare panel. Hmm... Im going to need to think about this one....
Thinkpad4by3's Law of the Universe.

The efficiency of two screens equally sized with equal numbers if pixels are equal. The time spent by a 4:3 user complaining about 16:9 is proportional to the inefficiency working with a 16:9 display, therefore the amount of useful work extracted is equal.

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Re: 2 - Thinkpad A30p - Swap LCD and backlight not working on 2nd???

#5 Post by RealBlackStuff » Thu Aug 31, 2017 5:33 pm

Check fuses F13 and F8 near the LCD-connector on the mobo.
AFAIK one of them feeds the LEDs and the backlight.
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kfzhu1229
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Re: 2 - Thinkpad A30p - Swap LCD and backlight not working on 2nd???

#6 Post by kfzhu1229 » Fri Sep 01, 2017 9:08 pm

RealBlackStuff wrote:
Thu Aug 31, 2017 5:33 pm
Check fuses F13 and F8 near the LCD-connector on the mobo.
AFAIK one of them feeds the LEDs and the backlight.
F8 is NOT under the LCD connector - it's under the DOCK connector
Also does A31 series have different fuse labels than A30 series? I remembered fixing F19 and F8 did the job on my A31p! F8 is the LEDs and F19 is the backlight.
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