Asus k55vd does not power on

[meraklinetx]

Hi friends, i had Asus K55vd laptop, before it was powering on and working well , I disassembled it for cleaning, and realised that some pins(3 of pins next each others) were went in corrosion on super io chip U3001 (IT8517E/HX) , so I decided to clean and resolder them with flux and hot air stations, and I made it soldered properly well all pins (this is not the first time I replaced an super io chip and I inspect under microscope that all pins soldered well and there is no touching pins each other)

After then, I want to test it and make all connections, when connected to bench psu, the amp meter shows 0.07a then instantly drops to 0.02a (which is normal stand by start up stage) but when push to the power button it doesn't start up and remains on at 0.02A stage. After I checked some voltages power button has 3.29V and when pressing switch it goes to 0V but laptop is not turning on, also when measuring PL8101 coil I get 5.02V and 5v always on is present but when measuring PL81000 coil I get 0.13V instead of 3.3v strangely those are 3.3v and 5v always on coils also when I test pin 9 of RT8239B (3.3/5V power regulator chip PU8100) I also get there 0.13V instead of P 3VSUS LX 30) according to board view file. Other voltages are seems OK expect 3.3v , I also check for on short circuit on 3.3V coil line, but there is no short circuit.

So what you think guy's?? What might be the problem?? Is it RT8239B ?? (I don't have spare to test it , what can I use as equivalent to RT8239B similar to TPS series?? Like 51125 ?? If so ??

Please guy's help me what might be the problem??

[meraklinetx]

Re: Asus k55vd does not power on

I get 0.13V on yellow markings instead of 3.3V strangely 😂🤣

[SMDFlea]

Re: Asus k55vd does not power on

"what can I use as equivalent to RT8239B similar to TPS series?? Like 51125 ?? If so ??"

According to the TI cross reference tool no,not a pin compatible one anyway - https://bomcross.ti.com/en/search?searchTerm=RT8239B

[meraklinetx]

Re: Asus k55vd does not power on

"what can I use as equivalent to RT8239B similar to TPS series?? Like 51125 ?? If so ??"

According to the TI cross reference tool no,not a pin compatible one anyway - https://bomcross.ti.com/en/search?searchTerm=RT8239B

Thanks my friend for your Quick reply 😂🤣 so what's your opinion about the problem??, I might damaged the rt8239 accidentally??

[meraklinetx]

Re: Asus k55vd does not power on

Any help, idea and suggestions please?? That why I get 0.13V on 3.3v coil instead of 3.3V ?? If rt8239A damaged why 5V coil is ok ??

[mon2]

Re: Asus k55vd does not power on

The regulator offers 2 independent regulators inside a single package. It is possible that 50% is working while the other half is not.

Can you power down, remove the battery and check the resistance on the coil related to the 3v3 rail? Place your meter in resistance mode, black probe on ground and red on the coil for this rail.

What is the reading? Perhaps you have a shorted cap on this rail?

Also, which version of this motherboard do you have? Can only find boardview and a service guide for this chassis. No schematics.

[Sametbey]

Re: Asus k55vd does not power on

For RT8239 to work, it must be 19v at 11 pin , 3.3 V at 12 pin, 3.3 V at 13 pin and 3.3 v at 6 pin ( powergood ). are these measurements complete? voltage outputs and after can be shortcircut. you can try by injecting voltage.

iyi çalışmalar.

[meraklinetx]

Re: Asus k55vd does not power on

UPDATE: before the latest posts, I replaced RT8239B with RT8243A for test purposes only, (because I don't have other
identical for test) which is according to the datashets , both are same even resistance and capacitor values for circuit, and currently composition starts with 0.07A and with no start as well, also 5V always disappeared, 3.3v also not present (I sure that the RT8243A, working OK and not damaged) but I am not sure that if they really identical as well, but according to both datasheets they are identical. Then I removed RT8243a again and put back old RT8239B and voltages were same before 5V present again and there were 0.13V on 3.3V coil instead of 3.3V

[meraklinetx]

Re: Asus k55vd does not power on

The regulator offers 2 independent regulators inside a single package. It is possible that 50% is working while the other half is not.

Can you power down, remove the battery and check the resistance on the coil related to the 3v3 rail? Place your meter in resistance mode, black probe on ground and red on the coil for this rail.

What is the reading? Perhaps you have a shorted cap on this rail?

Also, which version of this motherboard do you have? Can only find boardview and a service guide for this chassis. No schematics.

Thanks for your answer, I test it for an short circuit on 3.3V rail by incejting an 3.3v with and bench psu and nothing were heating also current composition was 0.06A while incejting 3.3V on rail,

Also I measured both Coil resistance, its 4.3K ohm for 3.3v coil, and 23.3K ohm for 5V coil, I don't know that, if those values are in normal range, I don't think that's it's a short in line of 3.3V coil but may have , because 4.3Kohm comes me a few less ����

[mon2]

Re: Asus k55vd does not power on

Monitor pin # 13 as there are differences in the A vs. B version of the component.

See attached. There may be other differences.

Grab the original component that you need for this repair. Aliexpress -> search for this exact p/n RT8239BZQW -> sort by the # of orders.

The coil resistance to ground seem good to me. If there was a short, you would have a much much lower resistance for these rails. Then current injection will force the shorted cap to heat up / fall apart right in front of your (protected) eyes.

As per above post, what is the value @ pin 11 ?

Are the feedback resistors to generate the feedback voltages @ pin1 and pin 5 ok? It is possible that if one of these parts is missing, the regulator is quickly shutting down due to the proper and expected feedback voltage. Power down, remove battery and confirm that each FB resistor in the voltage dividers is the proper value and that they are making the contacts to this Richtek controller.

[meraklinetx]

Re: Asus k55vd does not power on

For RT8239 to work, it must be 19v at 11 pin , 3.3 V at 12 pin, 3.3 V at 13 pin and 3.3 v at 6 pin ( powergood ). are these measurements complete? voltage outputs and after can be shortcircut. you can try by injecting voltage.

iyi çalışmalar.

Thanks you my friend for your reply, I measured the pin numbers that you mentioned, at pin 11, 19V present, but at pin 6 there is no voltage, its 0.01 almost zero, at pin 12 it's strangely 6.53V not 3.3V 😂🤣😅 also at pin 13 it's 2.8V not 3.3V also, by the way , I checked the pin 2 and 4 which is an enable signal for 3.3 and 5v , at pin 2 it's 2.8V but at pin 4 it's 4.99V (almost 5V)

Yardımcı olduğun için teşekkür ederim kardeş bu arada bende Türk üm , form kurallarına aykırı değilse, sana Türkçe yazabilirim, nedir durum kardeş, acaba chip mı bozuk ??

[mon2]

Re: Asus k55vd does not power on

My apologies. I posted the "A" example schematic earlier (see above).

It should have been "B" version of the chip.

Please see attached from the Richtek datasheet.

So, with the "B" chip on your system, do you see the FIXED rails (always on) @ pin 15?

Pin 15 should be +3v3

Pin 14 should be +5v0

these are independent fixed regulator outputs.

Pin 11 Vin @ 19v sounds good.

Your English is fine but used Google translate to convert Turkish to English. It works fine as well.

[meraklinetx]

Re: Asus k55vd does not power on

My apologies. I posted the "A" example schematic earlier (see above).

It should have been "B" version of the chip.

Please see attached from the Richtek datasheet.

So, with the "B" chip on your system, do you see the FIXED rails (always on) @ pin 15?

Pin 15 should be +3v3

Pin 14 should be +5v0

these are independent fixed regulator outputs.

Pin 11 Vin @ 19v sounds good.

Your English is fine but used Google translate to convert Turkish to English. It works fine as well.

Thanks my friend for the all information , here is the all voltages that I measured on RT8239B

PIN1 0V, PIN2 2.76V, PIN3 1.94V, PIN4 4.99V, PIN5 0V
PIN6 0V, PIN7 4.57V, PIN8 0.13V , PIN9 0.13V (WHICH IS EXACTLY SAME VOLTAGE ON 3.3V COIL)
PIN10 0V , PIN11 19.54V, PIN12 6.53V , PIN13 2.20V ,PIN14 4.99V , PIN15 3.29V, PIN16 0.11V , PIN17 5.10, PIN18 5.10V
PIN19 10V And PIN 20 is 5.05V

[meraklinetx]

Re: Asus k55vd does not power on

Thanks my friend for the all information , here is the all voltages that I measured on RT8239B

PIN1 0V, PIN2 2.76V, PIN3 1.94V, PIN4 4.99V, PIN5 0V
PIN6 0V, PIN7 4.57V, PIN8 0.13V , PIN9 0.13V (WHICH IS EXACTLY SAME VOLTAGE ON 3.3V COIL)
PIN10 0V , PIN11 19.54V, PIN12 6.53V , PIN13 2.20V ,PIN14 4.99V , PIN15 3.29V, PIN16 0.11V , PIN17 5.10, PIN18 5.10V
PIN19 10V And PIN 20 is 5.05V

Any news about suggestions?? What do you think about voltages ?? Does it chip faulty or some other reason that the system doesn't work ??

[Sametbey]

Re: Asus k55vd does not power on

Your measurements show that there is a problem with the 3.3v output. You can see if there is a malfunction in the chip by removing the PJ8102 jamp after the 3.3v coil. Sometimes problems may occur after 3.3v S5 MOSFET (wifi card, sound chip gb). You can give voltage starting 1v after the jumper. measurements, the reds should be your greens.

[meraklinetx]

Re: Asus k55vd does not power on

I solved the problem , what am I an idiot ������ the problem was I just accidentally made short circuit the legs of the serial resistors (a tiny one, I attached picture) which was near the super io chip while renewing the solders of corroded legs of super io chips so , 2 of legs becomes short circuit on side of super io chip and that's why the laptop weren't get start while pressing power switch. So I switched the side of the serial resistors and the problem solved ������ see the pictures

So I advise you when working, if there was an problem after. Always inspect what you done before and recheck what you done ������ thanks for everyone who helped and wasted the valuable times with me

On pictures see that short circuit on the legs of serial resistor marked with blue, and the legs got short accidentally marked with yellow, it was on super io chip side but after I switched side the resistor, so short circuit side remain other side but it's not a problem because other side all pins are in common, then super io chip legs now not in short circuit, and laptop is working now