820-3115 green light and charges the battery but no fan spin. only draws 0.07A

[kevinklinkmuller]

Hi there!

Have a board here without any sign of water damage or anything else. charges fine, although the customer did complain that the light on the charger was dim and it wasn't charging. It does charge on my chargers.

It's not the DC in board. DCin is present at u7000. PPbus_g3h is present. although PPVBat_g3h_conn is showing 12.56v. I have caught it pulsing once or twice which was interesting. Maybe my multimeter?

 

[kevinklinkmuller]

PPVBat_g3h_conn goes from 30V to 0 in about 10 seconds and then repeats. once the board has had power for a little bit it's back to 12.56v

 

[2informaticos]

30V surelly???
Do you get any pulse at the secondary supplies?
Short power pads on the board for test.

 

[larossmann]

PPVBat_g3h_conn cannot be 30v since there is nothing that high in this area, even if you have the charger sending 18v directly to the battery(which can happen rarely but machine will turn off ISL if you plug a battery in when the top FET is shorted) it will be 18v. Something is off with those measurements.

 

[kevinklinkmuller]

Sorry i made a silly mistake. It's actually pulsing from 3v to 0. Sometimes it's a steady 12.56. really odd. Would u7000 be causing that?

 

[kevinklinkmuller]

wtf. now it's no longer showing a green light and the board is drawing 0.140A instead of 0.06A like it did before

 

[kevinklinkmuller]

Ok PPcharger DCIN is only measuring at 14V now at c7005 and R7005 is getting VERY hot

 

[2informaticos]

Remove F7040 and check voltage at C7040.
If bad, problem on ISL6259 area.
If OK, post resistance to ground on PPBUS_G3H and the coils of all secondary supplies.

Check first for correct voltage at L6995...

 

[kevinklinkmuller]

AHA!!!! before that resister im getting 17.62V. on the other side im getting 14.8. is that normal?

 

[2informaticos]

Post resistance to ground at C7005.
Remove C7005, if still the same value, U7000 is bad.

Don't forget to put back R7005 with correct value, 20 ohms.

 

[kevinklinkmuller]

Remove F7040 and check voltage at C7040.
If bad, problem on ISL6259 area.
If OK, post resistance to ground on PPBUS_G3H and the coils of all secondary supplies.

Check first for correct voltage at L6995...

Ok so i took those steps. L6995 measures 3.46
C7040 is 0.03 before and after i took away f7040

Will try your next suggestion

 

[kevinklinkmuller]

Ok resistance to ground is 2 mega ohms at c7005 before removal

After removal of C7005 it is 2.5 Mega ohms


Still 14.8v at C7005 after removal

Shall i remove R7005?

 

[kevinklinkmuller]

Oh, wait so do you agree that I should remove u7000?

 

[kevinklinkmuller]

Ok so i have replaced U7000 and now I have 17.5 V back to it. However the baord is still not turning on. There is a green light now though! the board is drawing 0.01 amps.
I'm basically back to the initial issues before u7000 crapped out (I assume)

 

[kevinklinkmuller]

PPVBat_g3h_conn is fluctuating like it did before. Is this board trolling me?

 

[2informaticos]

I was expected diode mode value there...
However 2M is no short, nor low value.
It is strange then that R7005 gets hot.

"Don't forget to put back R7005 with correct value, 20 ohms."
Did it?

If C7005 is removed, correct R7005 can only get hot by some avalanche process inside U7000; so change it.
Be sure no short on MOSFETs around U7000.

 

[2informaticos]

Your posts change too fast for me...

 

[2informaticos]

"Remove F7040 and check voltage at C7040."
Is stable in such case?

 

[kevinklinkmuller]

Yes R7005 is in place
To be honest, maybe R7005 didnt get hot. Maybe I just saw something that wasn't there. I was using freeze spray and that area did burn my finger, maybe could've been anything. Yes voltage at c7040 was stable when g7040 was off (have placed that back now)

 

[kevinklinkmuller]

Does anyone have any more suggestions? larossmann