[SOLVED]820-2936 - Works on DCIN, works on battery, trips the charger if both connected.

[gcain]

[SOLVED]820-2936 - Works on DCIN, works on battery, trips the charger if both connected.

Obviously a dead short somewhere to trip the charger. Issue is that I can't work out how to track it down; not sure where to inject power.

Board had many issues, I replaced U6900, Q5310, U7000 and finally got a green light and fan spin back.

Issue now is that it trips the power adapter if the battery is connected.

 

[dukefawks]

Known good battery? PPBUS voltage?

 

[gcain]

Sorry Duke, like I said, out of practise.

I get a green light, but light goes out as soon as I connect a battery and never comes on if the battery is connected first. The fan does keep spinning if the battery remains connected though.

Here are some readings I took;

Resistance between U7000::17 & ::18 = 3.0ohms

With DCIN


D6990::1 = 15.63
D6990::2 = 16.34
D6990::3 = 16.04

L6995::1 = 3.469
L6995::2 = 3.463

U6990::2 = 3.460
::3 = 3.460
::4 = 16.06
::5 = -
::6 = 3.469
::7 = 16.06
::8 = 3.460
::9 = 3.462
::10 = 3.302


With Battery

D6990::1 = 12.14
D6990::2 = 0.025
D6990::3 = 11.94

L6995::1 = 3.462
L6995::2 = 3.462

U6990::2 = 3.462
::3 = 3.460
::4 = 11.94
::5 = -
::6 = 3.462
::7 = 11.94
::8 = 3.460
::9 = 3.462
::10 = 3.302

I have cleaned up and resoldered U7000 and am pretty sure it's seated nicely with no shorts from sloppy solder bridges.

 

[dukefawks]

D6990::1 = 15.63
That means your PPBUS is going to 15.6V! Check resistance between 17/18, 27/28 and for shorted Q7030. If any are bad replace U7000 too.

 

[gcain]

You were correct, there was a shorted Q7030.

Mark solved please.