A31p won't power up

[3266fast]

One of my A31p won't power up.
If battery installed and AC power connected battery icon light.
Power button on keyboard or dock does nothing both with and without battery.
I have fully disassemble notebook and try again without ultrabay, lan, modem, lcd e.t.c. connected. No result.
After it I have check all fuses on motherboard. All ok.
Also I have check a big coils and found that L3 (5R6) between two ultrabay connectors does not have 5R6 resistance.
It looks like disjointed. For example, the similar coils in CPU VRM conform its marking.
Is it a good idea to replace this coil with the same or sililar?

[rkawakami]

Welcome to thinkpads.com!

The inductor resistance should be almost 0 ohms. If you are reading more than 10 ohms, then the inductor is "open". The "5R6" marking on top is a code for 5.6uH, the inductance value of the coil. If you can find one which is the same size and shape and has the same 5R6 marking, then that will work. I do not have an A31p opened up right now but most of the inductors that I have found on T2x system are made by Sumida. You can try looking for this part at these two places:

http://digikey.com/scripts/DkSearch/dksus.dll
http://www.mouser.com/Search/Default.aspx

Enter "Sumida 5r6 inductor" in the Part #/keyword box. You can then check the datasheet or catalog page number link(s) to see if any one of the listed parts matches your inductor. With the correct part number, you might be able to find a local source for it.

[3266fast]

Welcome to thinkpads.com!

The inductor resistance should be almost 0 ohms. If you are reading more than 10 ohms, then the inductor is "open". The "5R6" marking on top is a code for 5.6uH, the inductance value of the coil. If you can find one which is the same size and shape and has the same 5R6 marking, then that will work. I do not have an A31p opened up right now but most of the inductors that I have found on T2x system are made by Sumida. You can try looking for this part at these two places:

http://digikey.com/scripts/DkSearch/dksus.dll
http://www.mouser.com/Search/Default.aspx

Enter "Sumida 5r6 inductor" in the Part #/keyword box. You can then check the datasheet or catalog page number link(s) to see if any one of the listed parts matches your inductor. With the correct part number, you might be able to find a local source for it.

Right you are.
Looking for 0R7 colis in VRM and think it mean a 0.7Ohm, like resistor. ))
But in VRM resistens mesured on the coil grows up until capacitors are charching...
I read infinity between contacts of this 5R6 coil, while the same contacts reads short in the 0R7 into VRM.
(I have some T2x boards, but it does not contain 5R6, only other nominals. I'll try to find it in the dead severboards I have.)
But battery control and charge scheme works correctly - maybe I am in a wrong way?
A weak HF sound heared from connected AC adapter changes its freq when power button push.
I have some experience in the desktop motherboards repair but know almost nothing about notebook's motherboard.
In desktops south bridge powers up by 5Vsb short or by RTC oscillator short.
Desktop may not powers up in the case of: missed 32768Hz clock, dead MIO, dead SB, and, of course, 3.3/5/12V to GND short.
And what about notebooks?