Dell Precision 7510 charge battery and left side board problem.

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

Ok i just desolder PU101 but still 20Ω
Should i proceed with PU1001?

[Spider1211]

Re: Dell Precision 7510 charge battery and left side board problem.

Sure, wont hurt to try.

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

Desoldered PU1001 too, still 20Ω on both jumpers pins.

[Spider1211]

Re: Dell Precision 7510 charge battery and left side board problem.

Post resistance to ground value on all all coils.

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

PL101 185Ω
PL100 several ΜΩ (not stable)
PL301 60Ω
PL700 several ΜΩ (not stable)
PL701 ~300KΩ
PL1401 7.8Ω
PL1400 7.8Ω
PL201 ~370Ω
PL1202 5Ω
PL1201 5Ω
PL1200 5Ω
PL1700 2.4Ω
PL800 66Ω

[Spider1211]

Re: Dell Precision 7510 charge battery and left side board problem.

Hmmm, try checking circuits connected to 5VALW. Refer to page 4 and 67, check the load switch IC such as UZ26.

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

Check for resistance to GND, correct?

[Spider1211]

Re: Dell Precision 7510 charge battery and left side board problem.

Easiest way in my opinion would be to just unsolder it and check both sides. Taking uz26 as example, measure resistance on pin 1,2 to ground then 13,14 to ground.

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

Removed UZ26 still 20Ω to GND.
Pin 1 & 2 20Ω to GND
Pin 13 & 14 (right above pin 1 &2 if i measured correctly) show infinity.

Keep in mind PU101 and PU1001 are still desoldered.

[Spider1211]

Re: Dell Precision 7510 charge battery and left side board problem.

Had an almost similar issue a while back. In my case it was a dead Core voltage controller and a USB protection IC. Try removing PU1100 and see if that changes anything.

Last resort would be to inject voltage on the 20Ohm line. Although not much current would flow, at 5V about 250mA to be expected. Might not be enough to get hot but something might get warm.

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

After desolder of PU1100 i got 85Ω on all pins mentioned above, no more 20Ω.
Is this resistance normal?

[Spider1211]

Re: Dell Precision 7510 charge battery and left side board problem.

By all pins you mean +5V_ALW, correct? Does both side of PJP102/3 still show same value or are they different now (pin1 is one value and pin 2 is different).

Still low but 85 is better than 20, so atleast that's some progress. Try checking different IC connected to +5V_ALW. Stuff like PU200, PU1200, PU1201, PU1400, PU1401, PU1402, PU1600, PU1700, etc.

Try resoldering everything back except PU1100 and see if its still 85Ohm. Then try removing the above mentioned IC and check if resistance increases(unless someone can provide a better approach). If you have a similar donor board, check what the resistance should be or maybe check the forum if someone with a recent post has a similar model and if they can provide the resistance value.

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

Yes i mean both pins of both jumpers have the same value, 85Ω.
Should i try with voltage inject or with 85Ω it will now work?

Last resort is to start desoldering what you suggest in order.
Damn, what a mess :p

[Spider1211]

Re: Dell Precision 7510 charge battery and left side board problem.

Just as a precaution, check if there is no solder bridge remaining after you disoldered pjp102/3.

Dont inject voltage if the driver chips are desoldered, at 85ohms (injecting 5V max) not much would happen anyway.

Well, since removing pu1100 (vcore related) changed resistance from 20 to 85 I'd suggest starting around vcc core chip first (pu1200, etc)

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

Just as a precaution, check if there is no solder bridge remaining after you disoldered pjp102/3.

Dont inject voltage if the driver chips are desoldered, at 85ohms (injecting 5V max) not much would happen anyway.

Well, since removing pu1100 (vcore related) changed resistance from 20 to 85 I'd suggest starting around vcc core chip first (pu1200, etc)

Okay, so i solder back everything (except PU1100) and cleaned up very well the jumper pins.
Now i have 80Ω on upper pins of both jumpers, bottom pins (the ones that are connected to PL102) have very high resistance.

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

Just desolder PU1200, now resistance on upper pins of both jumpers increased to 90Ω, still low.
Should i desolder PU1201, PU1202?

[Spider1211]

Re: Dell Precision 7510 charge battery and left side board problem.

Should i desolder PU1201, PU1202?

Sure, try and see what happens. If no change, resolder all ICs and replace PU1100 with a known good chip and recheck resistance value. Around 120-170 Ohm should be OK for that rail.

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

Ok, so far PU1100 is confirmed faulty
The PU1200 is ok? 10Ω resistance increase is normal?

[Andreasbest]

Re: Dell Precision 7510 charge battery and left side board problem.

Sure, try and see what happens. If no change, resolder all ICs and replace PU1100 with a known good chip and recheck resistance value. Around 120-170 Ohm should be OK for that rail.

Hello!
Removed all PU1200, 1201 & 1202 but resistance still stuck at 97Ω.
What do you suggest next?

[Spider1211]

Re: Dell Precision 7510 charge battery and left side board problem.

Resolder everything back except those that caused resistance to increase when removed. I would replace those, especially PU1100.

Once you have resoldered and replaced necessary parts, measure resistance again. Then resolder the PJP jumpers. If it is still within 90ish ohms, try to power on and see what happens.