ASUS ChromeBook C434T not powering on, need schematic

[mferna14]

Hi, I am working on an ASUS ChromeBook C434T, not powering on at all. The motherboard in it is C434TA_MB REV:2. Does anyone have the Schematics or Boardview for this model. The amp meter is stuck on 5v & does not turn on, no liquid spill., & it look clean, this model is with the USB-C charge ports. Any help will be great appreciate. Thanks

[LarrySabo]

Re: ASUS ChromeBook C434T not powering on

Any luck? I have same model with same symptoms (charger LED unlit).

[mon2]

Re: ASUS ChromeBook C434T not powering on

@LarrySabo - start a fresh thread in the laptop forum. This is an Asus so schematics are in the witness protection program.

However, perhaps you can locate the DCin connector -> post pics of the mosfets that follow and the charger IC onboard. Often, the fault is with the DCin mosfets unless there was some liquid or other damage to the unit.

[gobo]

Re: ASUS ChromeBook C434T not powering on

I had the same fault. I was able to fix it. The 3.3V converter and the usb control system were damaged. Everything works except the sound on the speakers (there is on the headphones). I am looking for a schematic or application for the max98927 chip.

[mferna14]

Re: ASUS ChromeBook C434T not powering on

Kindly inform us the chip number & the location of the part. What you mean by this "The 3.3V converter and the usb control system were damaged" please elabroate, thanks

[gobo]

Re: ASUS ChromeBook C434T not powering on

The laptop came to me dead - 5V on the power supply and nothing else. The LED does not light up, does not start, does not charge the battery.
A short circuit in the 3.3V line was caused by ANX7447 (3ohm relative to ground). After replacement, no short circuit but the chromebook still did not start. Replacing the TPS62125 converter restored proper operation. The PA (audio amplifier) is still damaged, after replacing +98927 the speakers still do not work. There is a burnt path from the chip that I can't locate - I need a layout app or a schematic for Chromebook Asus C434T

[mferna14]

Re: ASUS ChromeBook C434T not powering on

Thank you very much... added trouble-shooting knowledge for future reference.

[EGPeppered]

Re: ASUS ChromeBook C434T not powering on

The laptop came to me dead - 5V on the power supply and nothing else. The LED does not light up, does not start, does not charge the battery.
A short circuit in the 3.3V line was caused by ANX7447 (3ohm relative to ground). After replacement, no short circuit but the chromebook still did not start. Replacing the TPS62125 converter restored proper operation. The PA (audio amplifier) is still damaged, after replacing +98927 the speakers still do not work. There is a burnt path from the chip that I can't locate - I need a layout app or a schematic for Chromebook Asus C434T

I have a C433t board with a different issue. I looked at the audio section and it matches your photo.

That burnt trace leads to the bottom of the left resistor in the area you circled.

If the system is still in your shop, hopefully this gives you audio back again.

[gobo]

Re: ASUS ChromeBook C434T not powering on

Thanks for the info, even though it's out of date. The identical PA works in some Xiaomi phones, I found a Redmi 6Pro diagram. In fact, this broken path connects one of the IC pins to ground through a 0 ohm resistor. Unfortunately, after repairing the connection and replacing the IC, the speakers still do not work. Headphones work.

[ONLY ROB81]

Re: ASUS ChromeBook C434T not powering on

Does anyone know where you can obtain Asus Chromebook schematics and boardviews from

[mferna14]

Re: ASUS ChromeBook C434T not powering on

Does anyone know where you can obtain Asus Chromebook schematics and boardviews from

It's all case by case, not a certain place to find ASUS Chromebook schematics and boardviews, they are spread all over the net & most are not even available. If you need a specific one, find on the net or this forum is the best to search for your needs.

[Bartoloni]

Re: ASUS ChromeBook C434T not powering on

Hi guys, i have also this laptop for a repair... it's charging only at 5V 170ma, looking atthe board there is a broken component near the type-c connector
there is also another type-c at the other side of the laptop but i think it's not a charging port (or is it?) because it s not taking any milliamps

... one of the sides of the component is connected to ground , and the residual parts are black (resistor? diode?)

if someone can measure o identify if is a diode7resistor thank you!

here some images:

[gobo]

Re: ASUS ChromeBook C434T not powering on

Have you checked the charger? There is the PD. It needs to switch to 15V charging.

[y00kileet]

Re: ASUS ChromeBook C434T not powering on

The laptop came to me dead - 5V on the power supply and nothing else. The LED does not light up, does not start, does not charge the battery.
A short circuit in the 3.3V line was caused by ANX7447 (3ohm relative to ground). After replacement, no short circuit but the chromebook still did not start. Replacing the TPS62125 converter restored proper operation. The PA (audio amplifier) is still damaged, after replacing +98927 the speakers still do not work. There is a burnt path from the chip that I can't locate - I need a layout app or a schematic for Chromebook Asus C434T

Thanks a lot for the info, I'm trying to help a friend repair the same model laptop with seemingly the same issue. I'm also measuring low resistance to ground on what I believe is the 3.3 V. How did you find out that the short circuit was in ANX7447? Just pure trial and error or was it getting hot or something similar? I'm seeing 5 V / 0.12 A but nothing seems to heat up. 3.3 V and 12 V converters seem to be working but the 3.3 V at the consumers gets dragged down to a very low voltage due to the almost short circuit to ground (I assume).

[y00kileet]

Re: ASUS ChromeBook C434T not powering on

Hi guys, i have also this laptop for a repair... it's charging only at 5V 170ma, looking atthe board there is a broken component near the type-c connector
there is also another type-c at the other side of the laptop but i think it's not a charging port (or is it?) because it s not taking any milliamps

... one of the sides of the component is connected to ground , and the residual parts are black (resistor? diode?)

if someone can measure o identify if is a diode7resistor thank you!

here some images:

Not sure if you're still working on this, but it's a diode exactly the same to the one to the right (and in the same orientation). I would guess it's for protection and not vital to the function of the laptop. See photo, sorry for the bad quality since it's taken through the lens of the microscope

[y00kileet]

Re: ASUS ChromeBook C434T not powering on

For the record, the Chromebook I was trying to repair "magically" started to work again when I was trying to find which circuit was responsible for the almost short that I measured on the 3.3 V near ANX7447. I started by injecting 1 V/1 A from an external power supply, and the current consumption was very low, i.e. didn't seem like a short. When I upped it to 2 V/1 A from the external supply it suddenly jumped to 3.3 V, which I guess must've been coming from the battery, even though I suspect state of charge was low since it had been "dead" for several months. Anyway it went from being dead (no charge LED, only consuming 5 V/0.12 A from the USB) to booting. When booting I had a screen saying the OS was corrupted and needed to be restored, and when I pressed Tab I could see that it was caused by a TPM error. Performing a battery reset cleared that error and the laptop now seems to work normally. Very odd, I have no clue why injecting the external voltage made it come back to life. Anyway good thing that ANX7447 wasn't broken.

[Richard_MQ]

Re: ASUS ChromeBook C434T not powering on

Hi All
New member here with a friend's C434T not powering on or charging. I suspect the battery is too flat for the charging circuitry to work and for some reason (probably safety, given what these batteries can do...) that prevents charging.

@y00kileet - please can you be more specific about where you injected the current?

I did wonder if it would be better to remove the battery for charging, when I did so I measure < 1V between red and black leads. I assume these are + and - battery connections - but I'd love to know if this is an appropriate place to start injecting charging current before trying it!
Thanks
Richard

[Andyd1970]

Re: ASUS ChromeBook C434T not powering on

Hi guys. Help! I have two of these C433T dead. Only pulling 5V and 0.5A and other one is 0.1A I have thermal camera but can't see anything get hot. One I am finding caps shorted around this IC. I'm trying to learn laptop board repairs, would appreciate any help.

[SMDFlea]

Re: ASUS ChromeBook C434T not powering on

Hi All
New member here with a friend's C434T not powering on or charging. I suspect the battery is too flat for the charging circuitry to work and for some reason (probably safety, given what these batteries can do...) that prevents charging.

@y00kileet - please can you be more specific about where you injected the current?

I did wonder if it would be better to remove the battery for charging, when I did so I measure < 1V between red and black leads. I assume these are + and - battery connections - but I'd love to know if this is an appropriate place to start injecting charging current before trying it!
Thanks
Richard

Hi guys. Help! I have two of these C433T dead. Only pulling 5V amd 0.5A and other one is 0.1A I have thermal camera but can't see anything get hot. One I am finding caps shorted around this IC. I'm trying to learn laptop board repairs, would appreciate any help.

This is a schematic request thread in the "Schematic Requests ONLY!" sub forum. Start a new thread here -> https://www.badcaps.net/forum/forumdisplay.php?f=23


Reminder: rules and organization of this section - https://www.badcaps.net/forum/showthread.php?t=117483

.

[Andyd1970]

Re: ASUS ChromeBook C434T not powering on

ops! sorry