Toshiba A665

[BlueMidnight]

Re: Toshiba A665

You (and Ohm's Law) have shown that the excess current must be moving through PU2. If the problem is not in/around PU2 itself, then it must be somewhere on +CHGRTC/+RTCVCC.

One thing to try is to remove D13. If the voltages go back up, that will tell you the problem is on the +RTCVCC side of the circuit. Otherwise, the problem is on the +CHGRTC side.

[Stevedb]

Re: Toshiba A665

Hi bluemidnight

I removed d13 and the voltagen on pu2 was 3,23 v i replaced d13 with one donorboard still the same 2,13 v . I removed bios battery the voltage on pu 2 was back 3,23v i replaced bios battery with donor board but the one is also 0.73v not charged but the voltage on pu2 is still ok. So i tried to start up the laptop but no luck. Still same problem power on light on buton, power on light on leds , no hdd activity and no spin 5 sec. Then noghting.

Is it because the bios battery is not good, no 3v??

What will be the next step?

[BlueMidnight]

Re: Toshiba A665

Hmm interesting. What are the voltages on D13 now? (with AC plugged and unplugged)

[Stevedb]

Re: Toshiba A665

With no battery you mean with now voltage input what you mean. I will measure it tomorrow

With ac pin 1=2,98V , 2=3,24V and pin 3=0,74V
With no ac and no bat. All pins 0V

[BlueMidnight]

Re: Toshiba A665

So, just to confirm:

D13 pin 1 (CMOS battery) = 2.98V
D13 pin 2 (+CHGRTC, the output of PU2) = 3.24V
D13 pin 3 (+RTCVCC) = 0.74

Assuming D13 isn't bad, the voltage difference between pins 1 and 3 is way too high for that diode. Maybe the readings are fluctuating.

Those readings are pointing to a short somewhere on +RTCVCC.

[Stevedb]

Re: Toshiba A665

Oh ok i will look at tha circuit also order 2 bios batteries xhen i measured without poxer they are 0,05 v is not good.

Thanks for you help i will look at circuit +rtcvcc

[Stevedb]

Re: Toshiba A665

So I am suck on u11 then the components on the +RTCVCC I do not find just as j2 or jcmos, c288 and c289 or c351, c348, c349 on the board.

Regards

Steve

[BlueMidnight]

Re: Toshiba A665

Don't worry about anything on the other side of a big value resistor for now (unless you see damage/corrosion that could bypass the resistor). C291, C348, c349, C351 are the interesting ones. They aren't marked, but you might be able to find them by using your multimeter to see which little brown capacitors are connected to D13. They must be near/underneath the PCH.

Alternatively, you can inject voltage on +RTCVCC with a power supply and find the hot spot.

But it is also possible the PCH (U11) is bad. Which is probably the end of that board.

[Stevedb]

Re: Toshiba A665

Hi bluemidnight

First of all happy newyear and good health on 2019.

So i replaced bios battery now i have abouth 1.09v on pin 3 . I do not have a power supply but can i do an short circuit on d13 to get power on pin3? Or can i damaged more maybey component witch is faulty will be hot?

Thanks for the help

Regards

Steve

[BlueMidnight]

Re: Toshiba A665

You'll need more current than PU2 can provide. Even with a power supply, it might be difficult to feel a hot spot if the PCH is the problem.

I would just try to find the capacitors by eye or with a multimeter. If you eliminate those as possibilities, then the PCH is the only remaining option.

It's quite possible that the spill around PU2 created a low-resistance path around PU2 and put too high a voltage on +RTCVCC. The absolute maximum voltage rating on that pin of the PCH is only 3.7V

[Stevedb]

Re: Toshiba A665

Hi blue midnight

I found capacitor c289 and resistor r284
Also i found R285 and R275
Also i found c291and c348, C349 en C351 on the bottom side .
I tested the capacitors with one pad disconnected the side from +Rtcvcc.

Only one i not found is R282 and C288 an jcmos.

Can we be sure that the pch is bad. I can also not find the ic for replacing on internet. Is it always the end of the board or can you replace it when you IR bga solder station? But i do not find the processor for replacing.

Thanks for the help

Regards
Steve

[BlueMidnight]

Re: Toshiba A665

R282 is 20K ohms and could not possibly pass enough current to explain the readings. But if you want to be sure, the RTCRST# components are almost always located near the SRTCRST# components (C289 and R284 on your board).

You found the water damage. The related power rail is showing signs of a short. And the only way this could logically happen is if the water damage caused an overvoltage situation on that rail. So, unless a capacitor shorted and saved the PCH, I'd say a bad PCH is the most likely scenario right now.

Yes, it is possible to replace a PCH with the right parts and tools. But it also requires experience and patience. It's something to do to learn a new skill. It won't save you money this time around (unless it was a much more expensive board), and your first attempts may end up destroying the board rather than fixing it.

[vivid04]

Re: Toshiba A665

hi, have anyone here encounter the unit with no sound on just a particular speaker?

mine have sounds coming from right fine, but the left is muted. my speakers are both good, but the left speaker wont work?

is it a capacitor or the audio ic itself?