DELL 3521 PS_ID Woes

[mcplslg123]

Modelell Inspiron3521
M/B-LA-9104P

Problem: PS_ID isfluctuating between 0.9V to 1.8V,Adapter Unknown. Laptop is booting fine with adapter only. Works with battery Only but doesnt charge.

Here is what i've observed and done so far.

01.Resistance on PJPDC,pin1=134K Ohms
02.PR904/900/906/905/902/903-all as per schematics(tested out of circuit)
03.PQ901-gate is stable 5V, Source /drain pulsing between 0.9V to 1.8V
04.PQ900-Collector is 5V, Base is 0.1V to 0.2V
05.Connectivity between SIO,pin16 and PD901,pin1 is intact.
06.PD901-PIn3 is 5V,Pin1 is pulsing as above.
07.No broken traces/corrosion around charging area.
08.PQ100/101-SOurce/Drain=19V,Gate=8.4V
09.PR102 is 19V.
10.I've removed PQ900/901 and jumpered PQ901 Source to Drain. Result is same. So PQ900/901 is not bad for sure.
11.PD901 is replaced,still same.
12.SIO,Main/EC bios flashed known good.
13.PL902 Is intact.
14.As a last resort,replaced SIO with anew one and flashed,Still same.

PS_ID in dell is simple circuit and always had success in resolving it. this is the first time i'm stuck and really out of ideas.

If anybody has further insights, please advise.

[mon2]

Re: DELL 3521 PS_ID Woes

1) Where are you measuring PS_ID ?

2) Remove PL902 and check the voltage @ PL902, pin # 1.

[mcplslg123]

Re: DELL 3521 PS_ID Woes

I'm measuring PS_ID on dc JACK,PIN1,PL902/PQ901,pin1 & 3/PD901,pin1 ,PR903-both sides as well as SIO,pin16.

I already tried removing PL902. After removing PL902, voltage on Pin1 is 0.10 and on pin2 is 0.3V and both ends pulses a bit.

I'm using my dc supply with dell PS_ID as power source. However, With a dell original 65W adapter, behaviour is same.

PS:If you leave the mb overnight and measure PS_ID at dc jack,pin1 ,its stable 3.3V next morning. But it starts pulsing again after 15-20 seconds.

[usyusy]

Re: DELL 3521 PS_ID Woes

also psid pin of charger must be in full contact with the charging jack on the board

[mon2]

Re: DELL 3521 PS_ID Woes

Agree with the last post. Had exactly this fault yesterday with a replacement dell laptop fan being not detected. Issue was the compression fit connector pin was not mating.

Do you have or can source an Arduino?

You can ping the adapter to confirm it is stable for the single wire IC:

https://medium.com/@Morikko/get-rid-...n-d731bf81f0f3

What does the logic board report with your setup? Not a Dell power supply??

A logic analyzer should be used to log the single wire data communication line. Low cost $10-$20 models will work here from AliExpress. Meter cannot properly reflect the serial coms but an oscilloscope can.

[reformatt]

Re: DELL 3521 PS_ID Woes

IIRC, the one wire chip in the charger gets its power from the laptop. When power is applied it sends out a small burst of data to identify the charger type etc. When I've looked at this previously with a scope, the PSID line is 3V, the data is output, and the line returns to 3V.

PQ900 is a protection circuit to switch off PQ901 if the PSID voltage exceeds 5V. So for troubleshooting you can remove it to rule it out. I'm assuming that PR901 is nostuff as this entirely shorts out PQ901.

PQ901 should be biased on at 5V which will switch it on (as source is 3V). PS_ID should float to 3V unless PD902 has an issue, or there is an issue at the EC end. PD902 is a zener by the looks, a sacrificial component if the voltage is too high on the input. So I'd be removing it to see what happens. You should see stable 3V as far as I can tell.

[mcplslg123]

Re: DELL 3521 PS_ID Woes

@reformatt, i agree with your views and is aware of the same. Thats the reason i removed PQ900/901 and jumpered PQ901 Source to drain to rule out anything bad with PQ900/901. PD902 is@ ,so not populated. EC is new and flashed with known good dump.

@usyusy, DC jack is perfect and adater's central pin is in good contact. Tested the same dc jack on another dell mb and it works fine.

[reformatt]

Re: DELL 3521 PS_ID Woes

I'd strip out all the protection stuff and recheck. PD901 is a diode clamp for ESD protection, PQ900 for over-voltage, PD902 a zener to again limit input voltage. In theory, removing all those components and bypassing PQ901, you should have stable 3V and the PS_ID should work. If not, you must have some issue with the PCB itself.

[usyusy]

Re: DELL 3521 PS_ID Woes

also track should be ok through connector to EC

[mcplslg123]

Re: DELL 3521 PS_ID Woes

I'd strip out all the protection stuff and recheck. PD901 is a diode clamp for ESD protection, PQ900 for over-voltage, PD902 a zener to again limit input voltage. In theory, removing all those components and bypassing PQ901, you should have stable 3V and the PS_ID should work. If not, you must have some issue with the PCB itself.

Yes, in theroy it should've worked with the steps i've undertaken but alas it doesnt. PCB tracks seeems fine under microscope but yes cant rule out pcb issues as there are layers underneath the surface.I'll check it again whenever i've some free time.

[usyusy]

Re: DELL 3521 PS_ID Woes

sir is it in practice that if the impedance of some point, pin, leg of any component or IC etc seems to be oK but may be the concerned component faulty? If yes, what can be this science.

[lapfix]

Re: DELL 3521 PS_ID Woes

Hello friends.

Problem: PS_ID isfluctuating between 0.100 and-0.150v,..Adapter Unknown. but Laptop is booting fine with adapter only... booting from battery too ...and can't charge the battery
Trying with psu and 2 knowon charger same issue..the motherboard come with a lot of flux and io repairing !

here's my measurements :

Connectivity between SIO,pin16 and PD901,pin1 is intact.

PL902v = 5.9v

PQ901 =
D = 5.9v
G = 0.162v
S = floating between 0.100 and 0.300v

PR905 = 10K
1= 5VALW
2 = 0.162v

PQ900 =
collector = 0.162v
base = 0.015v

PR903 = floating between 0.100 and 0.300v = 33ohm

PR902 = 2.2K
pin 1 floating between 0.100 and 0.300v
pin 2 3.3v

After removing pq900 and pd901...

PQ901 =

D = floating between 0.100 and 0.300v
G = 5.1v
S = floating between 0.100 and 0.300v

Removing PQ901

D = 5.9v
G = 5.1v
S = floating between 0.100 and 0.300

What to verify else...thank you

[lapfix]

Re: DELL 3521 PS_ID Woes

Update :
Solved one , it was PQ900 the faulty component.

+ with Dell , never try with PSU it gives me wrong voltages ( For PS id section ) .

[AdrenalinTL]

Need to follow this post. I know it's old butI have this same issue and need to know what the problem is. Such a dumb fault from Dell.