T43p voltage regulator problem

[MartinPi]

Hi i'm new on this very interesting forum about thinkpads, sorry for my english but i hope you can give me some advice and i can repair my laptop
problem is probably in some voltage regulator on mobo, or some "mercury switch" as i read in some topic, some servo, switch that keep laptop alive after push power button..

laptop wont start,
all fuses is ok
i tested bare mobo, only with CPU to prevent automaticaly shutdown (with small passive heatsink) i can hear high-pitch noise from mobo if it pluged to AC adapter, and i can measure 16,4V at system dc - after F2 and mosfets TPC8109 and TPC8014, if powered by battery too (but only not 16,4V, sure, but only voltage of batt) so i think this power circuit is ok

so measuring with AC adapter:
on F17 is 3,3V
on inductor L11 (in the middle of ultrabay batt connector and cd/dvd connector) is 1,8V
on two mosfets near the L4 inductor (under connectors for speakers and CMOS batt) is 3,3V
on two mosfets near the next inductor ( under L4, most down and right corner of mobo) is 5V
on inductor L8 (under CPU) is 1,5V
this all voltages get lost when i push power button, most of them very quickly, but the voltage on L11 1,8V get at about half (cca 0,6V - 0,7V) and decreasing very slowly, even the high pitch noise gets out

if i repeat whole this testing, but powered with battery i cant measure these voltages nowhere, but if i measure while trying to push power button i can hear short high pitch noise and the voltages try to get at the previously measured values but it stop very quickly... on voltmeter blink only 2,5V or etc, it depends where a measure and its whole.. it can be ADP3806? how can i test it?

[MartinPi]

so i am here with new info
when i measure VCC on maxim 1993 (under keyboard connector) it is 5V but when i press power switch it is 0V.. does anybody know where is source of this voltage? it is maybe the main problem

EDIT: that max1993 is powered by max1901 on the right of southbridge, V+ 16,47V is still there as a "5V always on", but the IO shutdown when press power button, what else is this voltage powering ? 3,3V and 5V how can i measure where is something shorted in case of is 1901 shuting down?

if i measure the 5V "rail" at "shunt" resistor (on 1901 it is pin CSH5 ans CSL5) voltage is 1,9mV
if i measure the 3,3V "rail" at "shunt" resistor (on 1901 it is pin CSH3 ans CSL3) voltage is 0,6mV
so i think there is problem with something using 5V from this 1901... any tips?

[axur-delmeria]

Try a google search for schematics of the T43. You'll find it eventually.

[MartinPi]

http://elektrotanya.com/ibm_thinkpad_t4 ... nload.html

only here is something but i can't download it

EDIT: i get it
ok as i wrote i measure on sense shunt resistor at 5V rail, there is current about 170mA.. it is the problem i think
on 1901 is pin 4 (ON5) and pin 28 (ON3) at ON3 there is still 3,3V, even after i push power button, but at ON5 pin 4 is less then 0,9V in case of it is shutdowned as i think..

so there is my final question
signal for ON5 and ON3 is from IO U28 (under PCMCIA, pin 76) for ON3 is in series resistor 0R but for ON5 is in series resistor 10K (R866, if you flip mobo, rotate to right 90°, find the right groud place of copper of a part of mobo with PCMCIA slot, and on the left up corner of this, are resistors R405 (ON3) and R866 (ON5)
if it powered by AC apdater on the R866 is 0V but if i press power button there is about 2,5V so i thing there is problem with something using ON5 and it is MAX1901 (U41, pin 4) and BD4175KVT (U61, pin 64,63) and one of them is probably bad.. which ? is this all correct or am i doing some fault?

[RealBlackStuff]

Once on elektrotanya, you have to be patient.
Under the picture it says:

This file is downloadable free of charge. ...processing
(You are not logged in, only 2 downloads per day possible for you.)

After a short time this changes to:

This file is downloadable free of charge: Get Manual
(You are not logged in, only 2 downloads per day possible for you.)

Click on Get Manual to download it.

[MartinPi]

yes i'll be waiting whole day (i have already downloaded some this day) so i must register

[MartinPi]

it is possible then MAX1901 is due the 5V generated from it has more load, PIN 4 ON5 has lower impedance? (voltage 2,5V on R866) i dont know where to fing problem.. in MAX1901 (U41) and BD4175KVT (U61) or in some over load of 5V of MAX1901?

other problem, on U61 pin 25 where is VDD15 i have over 15V full power 16,47V and it goes away when i push power button, but i cant find where is source of this VDD15 voltage.. even from schematics, anybody help?