Toshiba L500 blinking power LED

[whaldsz]

Re: Toshiba L500 blinking power LED

mosfet side has a problem, it could be PQ31 or PU7. The other side could be normal.

[spleenharvester]

Re: Toshiba L500 blinking power LED

PQ31 was replaced earlier on and tests OK on the diode setting so that leaves PU7. I'm hoping it's not because I have no APW7138 spare.

EDIT: MOSFET side only tests as short to ground with both adapter and battery plugged in. In any other configuration, it reads as infinity.

[spleenharvester]

Re: Toshiba L500 blinking power LED

Just had a thought. Is it possible the other MOSFET is a dead one? That would explain why it shows as short only when it's powered surely?

And could the other side definitely be normal? I've never seen 12.7ohms on a 1.05v line before.

[whaldsz]

Re: Toshiba L500 blinking power LED

You are doing resistance measurements with adapter or battery inserted or on?

[spleenharvester]

Re: Toshiba L500 blinking power LED

Battery inserted (laptop dead/off): Short on MOSFET side, 13.7ohm on opposite pad
AC only (laptop dead/flashing LED): Infinity on MOSFET side, 13.7ohm on opposite pad
AC + Battery when powered down: Short on MOSFET side, 13.8ohm on opposite pad
AC + Battery when powered up: Short on MOSFET side, 28.7ohm on opposite pad
AC only (after inserting and removing battery, LED stable): Short on MOSFET side, 13.6ohm on opposite pad

Maybe there's two different problems going on here? Seems it only reads shorted with battery inserted most of the time

Also, with CPU inserted, lots of the caps read only 29ohms yet it gets power (and burnt my fingers when I checked, the nasty thing). So you be right about it being normal.

[whaldsz]

Re: Toshiba L500 blinking power LED

I think resistance test should be done without battery or adapter on or it will mess your readings - components may appear shorted.

What is the reading without battery or adapter?

[spleenharvester]

Re: Toshiba L500 blinking power LED

Will do bud, I'm still pretty new to this haha.

Readings without are infinity on MOSFET side and 12.9ohms on opposite side.

LAN port shielding is not grounded if that is of significance.

[spleenharvester]

Re: Toshiba L500 blinking power LED

Also, it pulls <2W from the wall when it's charging the battery?

Since it's all getting very confusing, this is the line I'm looking at:



PJ14 has 1.05v on it when powered on, but PJ5 and PJ8 still test as shorted.

Also, TPS51117 is giving out 4.5v instead of what looks like 5v...

What's going on here?

[spleenharvester]

Re: Toshiba L500 blinking power LED

Think I've just made this thread way too confusing to read to be honest haha. Ah well, I think I'm close to the cause anyway.

[whaldsz]

Re: Toshiba L500 blinking power LED

Also, it pulls <2W from the wall when it's charging the battery?

Since it's all getting very confusing, this is the line I'm looking at:



PJ14 has 1.05v on it when powered on, but PJ5 and PJ8 still test as shorted.

Also, TPS51117 is giving out 4.5v instead of what looks like 5v...

What's going on here?

Could you check page 3 of the schematic and verify how things are connected? If PJ5, PJ8 are shorted, you wont get 1.05V at PJ14, that is according to your drawing on post #28.

[spleenharvester]

Re: Toshiba L500 blinking power LED

That's what's confusing me, too. But there is deffo continuity between PJ5/PJ8 and PJ14. I'll double check it.

There are components between them though, mind. That's just a very rough diagram of how the lines are connected.

EDIT: With PL7 (between PJ5/PJ8 and the MOSFETs) removed there is still continuity between PJ14 and PJ5/PJ8. So they must be connected some other way.

[spleenharvester]

Re: Toshiba L500 blinking power LED

Desoldered PJ5, PJ8, PJ14, and PJ2 (where the "????" is on the diagram). No change whatsoever. :\

Worth noting there is only 180ohm on a few TPS51117 points though.

[whaldsz]

Re: Toshiba L500 blinking power LED

Did you reflow your northbridge? If so that explains why those two rails are shorted. +VTT and 1.05VS is connected to northbridge chip. Better confirm this to be sure.

[spleenharvester]

Re: Toshiba L500 blinking power LED

I didn't when I desoldered the PJ points. But I seem to be SOL now.

Found short in a small area isolated to a tantalum cap. Removed the cap and the board was dead. Readded the cap and the board came went back to how it was. Replaced the cap and now the board is completely dead, with components everywhere reading as dead shorted. No +5v or +3.3v rails anywhere. Tried reflowing northbridge with no luck. :/

19V and 13.5V voltages are still there so the first part of the circuit seems to be OK. But a lot of the voltages end at the ISL62883 chip. Should I replace it?

[whaldsz]

Re: Toshiba L500 blinking power LED

Could you check the resistance to ground of PL4 and PL5?

[whaldsz]

Re: Toshiba L500 blinking power LED

You must have the 3.3V and 5V first. See page 4, make sure you have the voltage rails on S5 first, when on battery or AC.

Without 3.3V and 5V, your KB chip wont respond. If you do have these two voltages, you check if U22 Is ok. Only then you can proceed with troubleshooting the other rails on S0.

[spleenharvester]

Re: Toshiba L500 blinking power LED

Resistance to ground of PL4, power unplugged: Dead short
Resistance to ground of PL5, power unplugged: Normal (About 11Kish)
Voltage on PL4 when powered - 0v
Voltage on PL5 when powered - oscillating 0.22v~0.45v

So there does appear to be a problem there.

Also worth noting, the 4.5v that TPS51117 gave out previously has dropped to 2.5v, and +VBSP is missing (had 11.8v before)

[spleenharvester]

Re: Toshiba L500 blinking power LED

PQ25 is short, shows 002~070 in every direction on diode test. Honestly no idea how that could have happened, maybe it was the heat. I'll remove it and test out of circuit to be sure.

PQ23, PQ26, PQ24 are OK.

EDIT: Yep, 13v on one side of PQ23, nothing thereafter. If it's not PQ25, it's something very close by.

[spleenharvester]

Re: Toshiba L500 blinking power LED

Removed PQ25, test okay. Now I've gone along that entire line removing almost everything and it still reads in as shorted. Time to give up on this board I think.

Area of fault is +3VALW to +3VS, page 44. Removed almost everything except for Q10 and R406

[dj_ricoh]

Re: Toshiba L500 blinking power LED

every time i give i remove the big ic chip (when i order another board) but there is a 10% that i found the faulty in one of those IC