Hey Guys,
long time lurker and I have a problem which I have been working on and off with for a few months now and hit a dead end and it's driving me crazy haha. Any input is greatly appreciated and sorry for the long read, trying to squeeze most info here.
Now I know this thing is old and is really not worth my time anymore, but it has been a great learning curve for me.
This laptop was given to me for free and was not working at the time at all.
Initially it was missing 3.3v_ALW which was caused by PQ31 shorting and also damaged PU4 - TPS51427A.
I replaced both and had both rails.
There was still no sign of life and after checking I found another short ( I don't remember where initially) which I traced back to the I/O controller - ITE8502E. Also under close inspection the I/O seemed to have a small burn mark on top.
Replaced the I/O controller and the short was gone and laptop came to life.
Current state is I have power. The laptop is working properly. It boots, I can load into windows, I have had prime95 run ect. All stable.
What is still wrong is that I cannot get the battery to charge.
The original battery it came with was under voltage. So I bought a replacement 3rd party battery.
Both batteries upon plugging in with the charger make the onboard LED flash 4x orange 1 time white.
During post I get the message that the battery cannot be identified and won't be charged.
In windows the battery shows up as unknown with either 0% or 100% and not charging.
If I remove the ACin the laptop stays on and uses the battery. I can cold boot from the battery too without AC charger.
The original battery is faulty, so forget that...all tests are done with the 3rd party.
BIOS shows power supply is correct so center pin is fine there too.
I have tried to trace so many lines and am trying to understand the problem...the only thing I can find which does not add up is that:
Pullup resistor RP8 on the SMBclk0 line is only 1.9k ohm not 2.2k
Resistor PR124 on the PBAT_PRES# line is 2k ohm and not 10k
Now, removing either of these makes the other the correct value (?!) why? They are not related apart from the 3.3v rail. When de-soldered their values are correct and make the other in line the correct value, it's really strange. I have swapped them too from a donor board, same result.
I have bought another faulty motherboard (has a hole in it) as a donor board and both resistors in line are the correct values 2.2k and 10k on the donor board.
smbdat0 line is 3.3v with and without battery
smbclk0 line is 3.3v without battery but only 0.5v with battery.
I do not have an oscilloscope to check if there is talk on the line.
I have again changed the i/o controller from the donor board to this one, same result.
I have changed the charging chip twice PU8 - MAX8731A (1 new, 1 from donor) with same results.
I really don't know what else I can check. My understanding so far is that there is potentially no smbclk talk on the line which in turn is making the charger chip not turn on.
It would make sense also why the error message comes up as it cannot read the battery % or know anything about it. Same in windows, no idea about state. I tried a battery info program in windows and results come back unknown.
Now SMBclk0 and SMBdat0 lines go Battery - MAX8731A - I/O.
Charging chip and I/O I have replaced each twice already, new and from donor...so it really makes me wonder if it is the replacement battery...but then the 2 resistors are still not quite right either so i'm unsure.
Any feedback is most welcome.
I'll post schematic and PU4 measurements.
PU4 - MAX8731A without battery with battery
01 - GND / GND
02 - 2.36v / 2.36v
03 - 4.09v / 4.09v
04 - - / -
05 - - / -
06 - - / -
07 - - / -
08 - 15mv / 15mv
09 - 3.37v / 3.36v
10 - 3.37v / 0.51v
11 - 3.37v / 3.36v
12 - GND / GND
13 - 3.29v / 3.28v
14 - GND / GND
15 - 150mv climbing up / 10.8v
16 - 150mv climbing up / 10.8v
17 - 150mv climbing up / 10.8v
18 - 150mv climbing up / 10.8v
19 - GND / GND
20 - 0v / 0v
21 - 5.3v / 5.3v
22 - 19.7v / 19.7v
23 - 150mv climbing up / 10.8v
24 - 150mv climbing up / 10.4v
25 - 5.3v / 10.4v
26 - 5.3v / 5.3v
27 - 19.7v / 19.7
28 - 19.7v / 19.7
With climbing up I mean each time i measure it is a higher value...started at around 150mv and becomes higher after 2minutes it was at ~400mv and climbing.
long time lurker and I have a problem which I have been working on and off with for a few months now and hit a dead end and it's driving me crazy haha. Any input is greatly appreciated and sorry for the long read, trying to squeeze most info here.
Now I know this thing is old and is really not worth my time anymore, but it has been a great learning curve for me.
This laptop was given to me for free and was not working at the time at all.
Initially it was missing 3.3v_ALW which was caused by PQ31 shorting and also damaged PU4 - TPS51427A.
I replaced both and had both rails.
There was still no sign of life and after checking I found another short ( I don't remember where initially) which I traced back to the I/O controller - ITE8502E. Also under close inspection the I/O seemed to have a small burn mark on top.
Replaced the I/O controller and the short was gone and laptop came to life.
Current state is I have power. The laptop is working properly. It boots, I can load into windows, I have had prime95 run ect. All stable.
What is still wrong is that I cannot get the battery to charge.
The original battery it came with was under voltage. So I bought a replacement 3rd party battery.
Both batteries upon plugging in with the charger make the onboard LED flash 4x orange 1 time white.
During post I get the message that the battery cannot be identified and won't be charged.
In windows the battery shows up as unknown with either 0% or 100% and not charging.
If I remove the ACin the laptop stays on and uses the battery. I can cold boot from the battery too without AC charger.
The original battery is faulty, so forget that...all tests are done with the 3rd party.
BIOS shows power supply is correct so center pin is fine there too.
I have tried to trace so many lines and am trying to understand the problem...the only thing I can find which does not add up is that:
Pullup resistor RP8 on the SMBclk0 line is only 1.9k ohm not 2.2k
Resistor PR124 on the PBAT_PRES# line is 2k ohm and not 10k
Now, removing either of these makes the other the correct value (?!) why? They are not related apart from the 3.3v rail. When de-soldered their values are correct and make the other in line the correct value, it's really strange. I have swapped them too from a donor board, same result.
I have bought another faulty motherboard (has a hole in it) as a donor board and both resistors in line are the correct values 2.2k and 10k on the donor board.
smbdat0 line is 3.3v with and without battery
smbclk0 line is 3.3v without battery but only 0.5v with battery.
I do not have an oscilloscope to check if there is talk on the line.
I have again changed the i/o controller from the donor board to this one, same result.
I have changed the charging chip twice PU8 - MAX8731A (1 new, 1 from donor) with same results.
I really don't know what else I can check. My understanding so far is that there is potentially no smbclk talk on the line which in turn is making the charger chip not turn on.
It would make sense also why the error message comes up as it cannot read the battery % or know anything about it. Same in windows, no idea about state. I tried a battery info program in windows and results come back unknown.
Now SMBclk0 and SMBdat0 lines go Battery - MAX8731A - I/O.
Charging chip and I/O I have replaced each twice already, new and from donor...so it really makes me wonder if it is the replacement battery...but then the 2 resistors are still not quite right either so i'm unsure.
Any feedback is most welcome.
I'll post schematic and PU4 measurements.
PU4 - MAX8731A without battery with battery
01 - GND / GND
02 - 2.36v / 2.36v
03 - 4.09v / 4.09v
04 - - / -
05 - - / -
06 - - / -
07 - - / -
08 - 15mv / 15mv
09 - 3.37v / 3.36v
10 - 3.37v / 0.51v
11 - 3.37v / 3.36v
12 - GND / GND
13 - 3.29v / 3.28v
14 - GND / GND
15 - 150mv climbing up / 10.8v
16 - 150mv climbing up / 10.8v
17 - 150mv climbing up / 10.8v
18 - 150mv climbing up / 10.8v
19 - GND / GND
20 - 0v / 0v
21 - 5.3v / 5.3v
22 - 19.7v / 19.7v
23 - 150mv climbing up / 10.8v
24 - 150mv climbing up / 10.4v
25 - 5.3v / 10.4v
26 - 5.3v / 5.3v
27 - 19.7v / 19.7
28 - 19.7v / 19.7
With climbing up I mean each time i measure it is a higher value...started at around 150mv and becomes higher after 2minutes it was at ~400mv and climbing.
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