Toshiba Satellite L745-S4110 powers off no display

[SuperAman]

Hi guys I have a Toshiba Satellite L745-S4110 DATE5MBA16O. Laptop charges battery and shows charger connected but I soon as a I press the on switch the laptop doesn't turn on no display and all LED lights turn off after about 1 minute whether I press on switch or not if charger or batttery is plugged it turns off after a minute. I have a short somewhere but nothing is getting hot.
I have 3.3v bios pin #8 and battery charge connector.

resistance on coils. (ohms)

pl3 open near batt connector shows 6.7v then drops to about 3v when laptop turns off
pl4 115 one side 7v other side 3.3v
pl5 117 one side 10v other 3.8v
pl6 131 no voltage Ram coil?
pl7 29 no voltage Cpu coil?
pl8 23 no voltage Cpu coil?
pl11 11 no voltage North bridge coil?
pl12 13 no voltage Cpu coil?
pl13 13 no voltage Cpu coil?

Do I have a graphics or north bridge short? Any ideas before I dig deep into the schematics? Which I got here, thanks.

[piernov]

Re: Toshiba Satellite L745-S4110 powers off no display

If a 5V rail measures 3.8V it should be quite obvious where to look.

[SuperAman]

Re: Toshiba Satellite L745-S4110 powers off no display

I cleaned the board with alcohol it was dusty and resistance on
3v. = 121
5v. = 123
Ram coil = 133
19v = open
Bios pin 8 = 123
Cpu coil w/o cpu = 45
charging coil =open


PQ7 drain I have 19v all pins and source & gate 3.3v PQ9 drain all pins 3.3v. and source and gate 0v.

PQ8 drain I have 19v all pins and source & gate 10.8v PQ10 drain all pins 10.8v. and source and gate 0v.

Battery coil has 6.8v and drops rapidly to 0v until charger led turns off.

I have 3.3v standby on 3v. supply coil. I have no other voltages on the coils after it shuts off but is still plugged. Do I have short both 5v and 19v rails?

5v elctro cap holds 3.9v and slowly drops to 0v as led turns off. No 5v standby voltage. Nothing is heating up and my bench supply is only 15v and 2a max.

[SuperAman]

Re: Toshiba Satellite L745-S4110 powers off no display


In the picture above the small resistor I pointed to is short and also short to ground on both sides. Is that normal? Also I noticed, when I touch that area of the board while it is plugged in the led turns off instantly rather than the 30 secs it takes for it to turn off.

[SuperAman]

Re: Toshiba Satellite L745-S4110 powers off no display

I removed both resistors the one labeled 400 is giving me reading of 1.2 in the 200M setting and 6-18 in the 20M range? And 256K ohms in another multimeter. It's supposed to be 40ohms, no? The smaller resistor is shorted, is that normal? On page 8 of the schematics for the IC PM6686 it says these two resistors are connected to the feedback and adjusts the 5v line. Is the 400 resistor bad or is the small resistor bad? Not sure which is faulty or what the readings are supposed to be?