very weired issue with step dowd IC SY8208B!! please help

[Weelcup]

Hi friends.
I have an OMEN 17w board. no shorts in the board. but it cannot provide the 3.3v output from sy8208B IC. although the 5.0v is provided.
instead it only outputs 0.635v not 3.3v.

I have replaced the ic with a fully working sy8208B but still the same issue. I checked the diode values on the all pins of the SY8208B and compare it with the ones on the working board and it matched. So I really do not know what to check next. by the way, sy8208B warms up to 38C when I powers up the board. but no shorts or low resistant component are detected....

I did not replace the super IO chip yet. but wondering if it is the cause

any help will be much appreciated... I have attached the schematics... the ic I am referring to is PU2001..


thanks

[khaahk]

Re: very weired issue with step dowd IC SY8208B!! please help

Pin 5 has 3.3V?
How much current is drawn from psu?

[u666sa]

Re: very weired issue with step dowd IC SY8208B!! please help

any help will be much appreciated...

Since any help is appreciated. This kind of google search SY8208B нет 3.3 might provide some help.

[Francisco.s]

Re: very weired issue with step dowd IC SY8208B!! please help

Probably 5VS5_ON is present, but S5_ON is missing.

Try to reprogram IT8987.

[Weelcup]

Re: very weired issue with step dowd IC SY8208B!! please help

Probably 5VS5_ON is present, but S5_ON is missing.

Try to reprogram IT8987.

thanks for the advice. I suspected that but if I am not mistaken IT8987E is auto programable and not in need to reprogram like IT8586E. I just soldered a new IT8987E. but same issue is still present.

but thanks you very much for the help..

by the way.. S5_ON is present...

[Weelcup]

Re: very weired issue with step dowd IC SY8208B!! please help

Pin 5 has 3.3V?
How much current is drawn from psu?

thanks for the help
Yes the LDO 3.278V is present on pin 5...

this is a very complicated board in regards to the dc power tip. I was not able to power it on using powersupply to measure the current. but the thermal image shows only the warming ICs are the IO and Sy8208B are using the current. SY8208E temp is 38 and the IO chip is about 30C. of couse when the main battery removed. because when it is connect the currect go to the charge ic and rail. so it is charging correctly.

I expect around 0.1A or 0.2A only considering no heating issues ….

I tried to inject only 2V at the rail but no current consume.

all the resistor measures around the Sy8208B are correct.


thanks again

[Weelcup]

Re: very weired issue with step dowd IC SY8208B!! please help

Since any help is appreciated. This kind of google search SY8208B нет 3.3 might provide some help.

Thanks .. I downloaded the datasheet..

[Weelcup]

Re: very weired issue with step dowd IC SY8208B!! please help

what could possibly made SY8208B to output lower voltage 0.635V while the 19v in and 3.280V enable signal are present?

[Francisco.s]

Re: very weired issue with step dowd IC SY8208B!! please help

Can you check for pulses in both pins of PC2008 with a oscilloscope?

There must be pulses in PC2008, and also in pin 6 of PU2001.

Also make sure you replaced PU2001 with the correct part, sometimes vendors sell this chips wrong, SY8208C instead of SY8208B.

[Weelcup]

Re: very weired issue with step dowd IC SY8208B!! please help

Can you check for pulses in both pins of PC2008 with a oscilloscope?

There must be pulses in PC2008, and also in pin 6 of PU2001.

Also make sure you replaced PU2001 with the correct part, sometimes vendors sell this chips wrong, SY8208C instead of SY8208B.

Thanks a lot.
Unfortunately, I do not have the oscilloscope yet. So it will be difficult to know if there are pulses.
However, can we assume 2 scenarios saying the pulses are there / the pulses are not there so what might be a responsible fault so that I just replace it.

In terms of wrong chip vendor. Well, I have a fully working omen board, exactly the same as the non working one. I brought the sy8208b from the working board. Also the marking code on the chip is MS3xx not the MT5xx so I am pretty sure it is the right one.

One more thing I just noticed. The bios chip got 2.02V when the I press the power button. I think it was supposed to come from the output of the sy8208B... just confused how did it get the 2V while the sy8208B tail only gets 0.635V...

Thanks again

[mcplslg123]

Re: very weired issue with step dowd IC SY8208B!! please help

Pin2-Pgood present??

[Francisco.s]

Re: very weired issue with step dowd IC SY8208B!! please help

So it will be difficult to know if there are pulses.

PC2008 is a fundamental component to make good pulses at PU2001 output.

Make sure PC2008 is in good condition or replace it, also check there is no open circuit between its pads and PU2001.

got 2.02V when the I press the power button....

It is not clear from schematic where +3VSPI cames from.

Usually it should come from +3VPCU.

[Weelcup]

Re: very weired issue with step dowd IC SY8208B!! please help

PC2008 is a fundamental component to make good pulses at PU2001 output.

Make sure PC2008 is in good condition or replace it, also check there is no open circuit between its pads and PU2001.



It is not clear from schematic where +3VSPI cames from.

Usually it should come from +3VPCU.

Thanks a lot.
I check them tonight. I will replace the ldo cap. And will let you informed of the results.

Thanks again.

[Weelcup]

Re: very weired issue with step dowd IC SY8208B!! please help

The ldo replacement did not work.

[mcplslg123]

Re: very weired issue with step dowd IC SY8208B!! please help

Pin2-Pgood present??

You didnt answered this

[smali]

Re: very weired issue with step dowd IC SY8208B!! please help

How many ohms showing PL2001 to Ground??

[khaahk]

Re: very weired issue with step dowd IC SY8208B!! please help

Disconnect PJP2001 and see if it makes 3.3v ok. If ok, then you've got some secondary rail using too much current.

[Weelcup]

Re: very weired issue with step dowd IC SY8208B!! please help

You didnt answered this

Sorry, the customer has taken the motherboard...