No power to KBC after chip change

[p1muserfan]

Re: No power to KBC after chip change

BQ24707 pin 5 and pin 6 voltages? I think that AC_IN# if pulled low by BQ24707 pin 5, should also pull low the KBC_ON# signal through D2703 opening Q2703.

Have 3v at pin 5 of 24707 and therefore 3v at pad 3 of D2703. Have 0 at pad 1 and 2 of 2703. Also have 0 at pad 2 of 2702 and 0 and pins 2,3,and 4 of RN2706. However, while remeasuring pins of Q2703, the board fired up on its own (I had reinstalled KBC since earlier post) and fan ran at high until I unplugged it. What just happened?

[p1muserfan]

Re: No power to KBC after chip change

Getting somewhere. Can now start the board only with the CMOS battery removed and shorting the power button. Got video and everything. Won't start with the CMOS installed however.

[loser18]

Re: No power to KBC after chip change

Also think it's just not soldered properly...

SIO/KBC/EC whatever you wanna call it, is a real pain...
My trick...

-desolder
-take off all old solder with desoldering wick
-tint a new solder, evenly
-position well and use hot air station withou any noozle
-use drag n drop techique with thinnest tip you've got (this will allow to get more solder underneath the legs which needs that)
-if any bridges use desoldering wick again
-once again reflow & when solder starts to melt push the Chip down firmly with twezers, get it cool,but still push the twezers...(THIS IS THE KEY STEP, many times I was too lazy to do this & and mobo didn't even start up, or was dead) but note in most cases I'm using lifted/used chips, which haven't.got straight legs as brand new ones...

All the procedure i'm doing under the scope...call me paranoid, but I can be 100% sure the connection is propper on first attempt...

Oh...and of course lot of flux...

[p1muserfan]

Re: No power to KBC after chip change

Also think it's just not soldered properly...

SIO/KBC/EC whatever you wanna call it, is a real pain...
My trick...

-desolder
-take off all old solder with desoldering wick
-tint a new solder, evenly
-position well and use hot air station withou any noozle
-use drag n drop techique with thinnest tip you've got (this will allow to get more solder underneath the legs which needs that)
-if any bridges use desoldering wick again
-once again reflow & when solder starts to melt push the Chip down firmly with twezers, get it cool,but still push the twezers...(THIS IS THE KEY STEP, many times I was too lazy to do this & and mobo didn't even start up, or was dead) but note in most cases I'm using lifted/used chips, which haven't.got straight legs as brand new ones...

All the procedure i'm doing under the scope...call me paranoid, but I can be 100% sure the connection is propper on first attempt...

Oh...and of course lot of flux...

I would agree with you but I had this problem before I changed the KBC. Along with a charging circuit issue (can't have battery installed with adapter connected, that will be addressed later, one issue at a time, lol), I think the board only starting with the CMOS removed is an RTC issue, dead crystal maybe? Need a frequency counter.

[loser18]

Re: No power to KBC after chip change

Depends on architecture...didn't see the schematics aa I'm on a phone...thought You just changed SIO cause no power etc...I don't even know what CPU architecture is this mobo...

[hazardus]

Re: No power to KBC after chip change

I would agree with you but I had this problem before I changed the KBC. Along with a charging circuit issue (can't have battery installed with adapter connected, that will be addressed later, one issue at a time, lol), I think the board only starting with the CMOS removed is an RTC issue, dead crystal maybe? Need a frequency counter.

Or a scope.

[whaldsz]

Re: No power to KBC after chip change

check Q6001. there should be 3.3v on all pins. It gives RTC_AUX_S5 going to PCH. If RTC_AUX_S5 is missing, laptop won't turn on.

[khaahk]

Re: No power to KBC after chip change

Pin 6 voltage of BQ24707?
You should have 0 at pin 5 when adapter is plugged in (Pin 6 above 2.3V). If pin 6 above 2.3 V and pin 5 is high then you may have a bad charger chip, hence no battery charging and no power to KBC chip...

[ktmmotocross]

Re: No power to KBC after chip change

looser18> wanna see good sio soldering? check this, no hotair.

from 2:00 it gets to the point
https://www.youtube.com/watch?v=5uiroWBkdFY

[loser18]

Re: No power to KBC after chip change

looser18> wanna see good sio soldering? check this, no hotair.

from 2:00 it gets to the point
https://www.youtube.com/watch?v=5uiroWBkdFY

Yeah...I've seen this guy on youtube few weeks ago...
He's got some real mad soldering skillz...what got me was how clean is his rework...gonna definetly order those "kimwipes"

[p1muserfan]

Re: No power to KBC after chip change

Pin 6 voltage of BQ24707?
You should have 0 at pin 5 when adapter is plugged in (Pin 6 above 2.3V). If pin 6 above 2.3 V and pin 5 is high then you may have a bad charger chip, hence no battery charging and no power to KBC chip...

With adapter plugged in I have 3.2v at pin 5 and 2.7 at pin 6. I thought having voltage at pin 5 was important? The other major issue with this board has been the charging circuit. Since fixing the first problem it had of a dead short (a bad capacitor), the board will only start with the adapter, I can't have the battery connected at the same time. When I tried to start the board with both battery and adapter connected, the board shorted again knocking out both charge chip fets (PU4004 and 4006). I changed both the charging chip and fets but now when the board does start (by removing the cmos, yet another issue), those fets are missing until I figure out what is frying them. I'm trying to deal with one issue at a time but have a feeling everything is related.

[p1muserfan]

Re: No power to KBC after chip change

Still having trouble getting 3v to KBC. Get 3v out of drain of Q2703 with no problem now but something else is dead between there and R2771. Not sure of path once it leaves drain of 2703

[tata123]

Re: No power to KBC after chip change

hey guys i have 0 volts on BQ24707 pin 5,6 and 19 volt on pin 20,19 ....?

is this normal

why is the nuvoton kbc chip made a strange noise when i put my finger on it?

[khaahk]

Re: No power to KBC after chip change

Still having trouble getting 3v to KBC. Get 3v out of drain of Q2703 with no problem now but something else is dead between there and R2771. Not sure of path once it leaves drain of 2703

Either R2771 is open circuit or KBC is shorted? Measure resistances.