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820-2915 reset charger and green light and fan spin but shutting charger off

G

grmacs

Member
Runs on battery not on charger only. Haven't been able to figure out what is going on with the charger circuit. Thought I had it but it died after booting up. NOw it seems it is shutting the charger off quicker. Tried changing dcin board. CHecked sys_onewire for continuity.

replaced iSL a few times checked resitors around it had a high 20 ohm resistor at r7021 and replaced it and caps around it thinking it was related to adapter sense at first. replaced q7080. reflowed smc being at times I had smc bc acok. Doesn't seem I can get voltage off charger long enough to get consistent readings off of ISL.

Not detecting a short on ppbus g3h ~.43V drop red probe to ground
 
G

grmacs

Member
its shutting the charger off too fast for me to get anything consistent around the ISL. my 3.42V and 16.5V is there for usually just a second. SOmetimes green light and fan spin but lately not getting that. Im not detecting short on ppbus g3h =.441V drop or 3.42V lines .358 voltage drop.
 
G

grmacs

Member
got some where. I was unsure placement of q7080 and went to adjust it and it broke. replaced that and now getting mostly consistent around u7000:

1-0
2-15V
3-3.95V
9-0
12-3.48V
13-3.48V
14-3.32V
15-0
17-1.7-1.8V pulsing!
19-5V
20-5V
27-1.7V-1.8V pulsing...

does the matching/pulsing 17 & 27 voltage imply u5420 issue? I know thats a problem but not sure what it means.
resistance:

17/18=2.7ohm
27/28=20.3ohm
 
2informaticos

2informaticos

Administrator
Staff member
"1-0
-----------
27-1.7V-1.8V pulsing"
Looks like a problem with Q7080; did you solder new one?

Post exact resistance value for R7080/81 and R7085/86; measured onboard, ohm scale.
 
G

grmacs

Member
took q7080 from other board. I think 2nd one I tried but wondering if soldered good. is there good way to test if soldered well? I tested to make sure I didn't have continutiy between smaller pads where possible.

7080- 99.3K ohm
81- 61.8k ohm
85- 444K ohm
86- 327k ohm
 
G

grmacs

Member
resoldered q7080. pulsing stopped but pin 17 is still 1.7V and pin 27 is still 1.7V. I'll try replacing q7080 again.
 
2informaticos

2informaticos

Administrator
Staff member
Probably bad solders at Q7080, or bad MOSFET.
With 0V at pin 1/U7000, you MUST get normal voltage at R7020.
 
2informaticos

2informaticos

Administrator
Staff member
Remove Q7080 and check continuity from its pads to other components.
Pay atention to Gate pads, go through holes on the other side.
 
G

grmacs

Member
Just got back to this one. You were right! I apparently didn't have a good solder job on Q7080. Being I'm new, I didn't realize importance of using good solder and have suffered some from thinking I had good solder joints and such, being this was from a bit ago, I think it was related to that. I now have 12.26V on PPBUS_G3H so looking at the SMC...
 
G

grmacs

Member
exactly 3.48V on both SMBUS_SMC_BSA_SDA/SCL. Heating SMC brought PPBUS_G3H to 12.48V. See slight tick on fan spin when putting to power. So assuming SMC isn't boosting to 12.65V? I'll reheat one more time and then replace if I can... not sure I have template for this SMC?
 
2informaticos

2informaticos

Administrator
Staff member
You should reball it first.
Direct heat stencil and solder paste is the easiest way.

Not too many balls, can be placed at hand too.
 
G

grmacs

Member
tried twice with same replacement chip and got 12.3V still. Try another? or...?
2nd round attempt feeling pretty good about the placement and contacts. First try I reheated after setting and gave it a bit too big of a tap! but also had 12.25V prior and after.
 
2informaticos

2informaticos

Administrator
Staff member
Looks too big difference.
Did you test the board alone, no battery, nor BIL connected?
Remove D6950 and check again, when board gets cold.
 
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