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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-19-2022, 10:40 AM
Re: Asus P2B | Slot 1 + Pentium II | no power

Hello!
There is no short between the +12v fan headers pin and ground.
I didn't try to flash another bios but still have some news.

The power supply [B]now turns on also with Q13 full connected[/B].
Not sure what happened, i cleaned better the board with ipa, did some tests with the multimeter and at the end soldered again the Q13 legs to see if the power supply still turns off or not.

Anyway the motherboard is like before, still dead with no light and no fans.
Seems...

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Last edited by AidenX; 07-19-2022, 10:57 AM.
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-13-2022, 12:13 PM
Re: Asus P2B | Slot 1 + Pentium II | no power

Yes, the power supply turns on and runs.
A long press of the power button turns it off. Seems all normal now.

CPU, RAM, GPU, led, fans, and a monitor was connected when i tried it and as i said nothing works, only the power supply. ...

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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-13-2022, 10:27 AM
Re: Asus P2B | Slot 1 + Pentium II | no power

So....i disconnected pin 1-3 of Q13.

The power supply turns on / off, the voltage is 11.80v (a bit low?) on pin 10 but it's still all dead.
No led, no fans, no beep, no signal like before.

It's just the power supply all alone. xD...

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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-13-2022, 08:05 AM
Re: Asus P2B | Slot 1 + Pentium II | no power

Well...at the beginning I thought I had to follow the boardview lines and see if there was any "break" in the connection between where it starts and each component... or at least find a different resistance value than the pure 0 ohm.

These things are quite new to me and not everything is clear.... sorry... ^^"
For example, there are times when things shorted or almost shorted to ground are "normal" and it doesn't help to understand what is really wrong. XD
But I'm trying...

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Last edited by AidenX; 07-13-2022, 08:31 AM.
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-13-2022, 07:22 AM
Re: Asus P2B | Slot 1 + Pentium II | no power

Uhm ok...

C66 has one pin with 0 ohm to ground and another with [B]38.02k[/B] ohms to ground, so it's fine right?
All the other pins in the +12v line have the same 38.02k resistance to ground.

[B]R93[/B] has one pin with [B]38.02k[/B] and the other with 42.70k to ground.
[B]Q13 [/B]has pin1 with 43.30k, pin2 (the tab) with 3.955M and pin3 (12v line) with again [B]38.02k[/B] ohms to ground.

Yes, there is that [B]3.84v[/B] on pin...

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Last edited by AidenX; 07-13-2022, 07:29 AM.
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-12-2022, 04:35 PM
Re: Asus P2B | Slot 1 + Pentium II | no power

So....if I understand the boardview correctly, the [B]+12v PIN #10[/B] ATX power connector is linked to:

C66 U1 U2 U3 CB81 R15 AGP PCI1 PCI2 PCI3 PCI4 SLOT1 SLOT2 R93 CB72 and the famous [B]Q13[/B].

PIN #10 to C66 has [B]000.0[/B] ohm, like to U1 U2 U3 etc...

The last 3 are different...[B]R93[/B] - [B]CB72[/B] - [B]Q13[/B].
Between them and the PIN #10 the resistance is NOT completely zero, but remains at [B]000.2[/B] ohms even after a while.

Also in my board the CB72 component...

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Last edited by AidenX; 07-12-2022, 04:56 PM.
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-12-2022, 01:21 PM
Re: Asus P2B | Slot 1 + Pentium II | no power

Yes, without cpu 0 beep is normal. xD
I only wrote how i tested if the power supply turns on/off [B]yesterday[/B] when still wasn't sure that the short was [U]ONLY[/U] on the +12v line.
So all the other components was disconnected just for keep them safe....

Sorry if i didn't write it clearly before! ^^"

I will try again with more in-depth tests and I'll keep you updated!

EDIT:

Tested the board again, this time with all the components.
CPU,...

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Last edited by AidenX; 07-12-2022, 02:07 PM. Reason: new tests
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-12-2022, 12:18 PM
Re: Asus P2B | Slot 1 + Pentium II | no power

Negative. I tried the board with only a fan connected (CPU_FAN) and the speaker (without cpu, ram, etc).
The fan didn't work and 0 beep.

In my board revision (1.02) D14 and D15 (with the CHA_FAN between them) are both missing.

I will see the boardview later! Again thanks for the help and all the info! ...

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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-11-2022, 10:07 AM
Re: Asus P2B | Slot 1 + Pentium II | no power

So i tested the board as you said, [U]without[/U] the +12v wire on PIN #10, and the power supply turns [B]ON[/B].

But the voltage on PIN #10 of the motherboard (not connected to the power supply!) isn't 0V....but[B] 3.84V[/B].

It's not normal...right? Re: Asus P2B | Slot 1 + Pentium II | no power

So i tested the board as you said, [U]without[/U] the +12v wire on PIN #10, and the power supply turns [B]ON[/B].

But the voltage on PIN #10 of the motherboard...

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Last edited by AidenX; 07-11-2022, 10:12 AM.
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-07-2022, 11:21 AM
Re: Asus P2B | Slot 1 + Pentium II | no power

Hello!

I understood this, and I also read the guide when I tried to fix the notebook motherboard here on the forum.
I had found various low values just near the CPU/GPU etc, even from 1-3 or 0.x ohms and in that case they were normal as you mentioned.

On that occasion, however, it had never happened that the [B]multimeter [COLOR="Red"]red [/COLOR]indicator lights up[/B] due to a low resistance, which is why I asked several times if it was normal or not! XD

...

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Last edited by AidenX; 07-07-2022, 11:47 AM. Reason: added photos of the working board used for the tests
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-03-2022, 03:08 PM
Re: Asus P2B | Slot 1 + Pentium II | no power

Ok i will try.

There are many capacitors around the board with about 36 ohms to ground (and the red light)...
This means they are all connected to the same shorted line or something like that?

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Last edited by AidenX; 07-03-2022, 03:16 PM.
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-03-2022, 12:34 PM
Re: Asus P2B | Slot 1 + Pentium II | no power

I just have a cheap digital multimeter....and i don't have a DC power supply anymore for the voltage injection. I will buy another one soon.

I will also try to ask the seller more details about the story of this board.

Say me if i can do something else in the meanwhile...

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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-03-2022, 11:42 AM
Re: Asus P2B | Slot 1 + Pentium II | no power

Hello....i did it (disconnected only pin 1 and 3, tab still connected).

[CODE]+ to pin 3 and - to the tab = 0.115V

- to pin 3 and + to the tab = nothing[/CODE]

pin 1 to tab is nothing in both sides.

But if i test the PCB part of pin 1 / 3 with tab, it's all like before....

The problem is somewhere else right?

Thanks...

Code:

Re: Asus P2B | Slot 1 + Pentium II | no power Hello....i did it (disconnected only

...
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-01-2022, 01:51 PM
Re: Asus P2B | Slot 1 + Pentium II | no power

Oh....sorry for the mistake... ^^"

I tested Q9 (still soldered on the board) as you asked:

[CODE]+ to pin 3 and - to the tab = 0.042V

- to pin 3 and + to the tab = 0.044V[/CODE]

Same values if i test pin 1 with the tab...and again that 36 ohms (with red light) in continuity mode...

Thanks!

Code:

Re: Asus P2B | Slot 1 + Pentium II | no power Oh....sorry for the mistake... ^^" I tested Q9 (still soldered on the board) as you asked:
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Last edited by AidenX; 07-01-2022, 02:02 PM.
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AidenX replied to Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

07-01-2022, 12:43 AM
Re: Asus P2B | Slot 1 + Pentium II | no power

Oh....really bad news so

I tested again Q9 and Q10 (without desolder them for now).

Source / Drain / Gate of Q10 doesn't beep....

Q9 is strange...has a different name/mark from all the other mosfets.... and it's normal that both drain and gate go to ground ?!

Anyways again, source to drain or gate has that low resistence of 36 ohms (and why the multimeter light is red ? O.o).

Also, i can't test if the southbridge get hot...as i said i can only left the...

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Last edited by AidenX; 07-01-2022, 12:47 AM.
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AidenX started a topic Asus P2B | Slot 1 + Pentium II | no power

in Troubleshooting Desktop Motherboards, Graphics Cards, and PC Peripherals

06-30-2022, 08:49 AM
Asus P2B | Slot 1 + Pentium II | no power

Hello!

I would like to repair this old motherboard that i bought weeks ago with some other old stuffs!

Sadly it doesn't work.

I tested the CPU, ram, etc with another slot 1 board and they are all fine.

Probably there is a short on the board, no power at all when connected to the power atx supply.

Also, the power supply works fine with other hardware, but do a strange noise after few seconds that is connected to this board...i think is all ready to explode! XD

Here some measures from the power connector...

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AidenX replied to Toshiba Satellite L750D - 19v missing on the main power rail

in Troubleshooting Laptops, Tablets, and Mobile Devices

06-30-2022, 07:46 AM
Re: Toshiba Satellite L750D - 19v missing on the main power rail

Hello!
At the end i replaced the bad board with a cheap good one that i found on ebay.
It has a different cpu and a strange crossfire between the apu and the discrete graphic card! XD

All works fine with the other parts of the notebook, the only problem that i found was the audio chip conexant that seems half dead in this "new" board!

Audio stop to play after few seconds ONLY with the internal speakers (and not with external things on the jack connector).

...

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AidenX replied to Toshiba Satellite L750D - 19v missing on the main power rail

in Troubleshooting Laptops, Tablets, and Mobile Devices

06-10-2022, 03:07 PM
Re: Toshiba Satellite L750D - 19v missing on the main power rail

Hello, in this days i found also the bios for this notebook.

Flashed it but still no display / no POST...

At least now i'm sure that the bios chip is fine and the problem is something else... ^^"

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AidenX replied to Toshiba Satellite L750D - 19v missing on the main power rail

in Troubleshooting Laptops, Tablets, and Mobile Devices

06-05-2022, 04:21 AM
Re: Toshiba Satellite L750D - 19v missing on the main power rail

@Vesko356 Good news! Finally after a loooong search, and [U]many strange and unreliable sites[/U] (with paywall etc..), i found the [B]schematic[/B] for this board model!

I'm not 100% sure that is the same revision, but better than nothing...

I hope it can help to understand the new problem on this unlucky notebook... x.x

[B]Thanks[/B]! ^^Re: Toshiba Satellite L750D - 19v missing on the main power rail

@Vesko356 Good news! Finally after a loooong search, and [U]many...

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Last edited by AidenX; 06-05-2022, 04:38 AM. Reason: added .pdf
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AidenX replied to Toshiba Satellite L750D - 19v missing on the main power rail

in Troubleshooting Laptops, Tablets, and Mobile Devices

06-05-2022, 03:00 AM
Re: Toshiba Satellite L750D - 19v missing on the main power rail

Mmm ? I only injected 1V - 2A days ago for find the bad cap thanks to Vesko's help! I didn't use the bench supply anymore after that.

The tests i did yesterday (post #35) was with the [B]original notebook power supply[/B] connected....maybe i wrote it wrong, sorry ^^"

I did it at 200° C but still nothing! :cRe: Toshiba Satellite L750D - 19v missing on the main power rail

Mmm ? I only injected 1V - 2A days ago for find the bad cap...

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Last edited by AidenX; 06-05-2022, 04:27 AM.
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