820-2850 replaced the q7085 now no green light

nate8organic

New member
820-2850 board had green light no power, smc bypass and it would spin. the q7085 had no voltage on pins 5-8 changed it out and now im getting 18v on pins 5-8 but the green light is gone and so is my smc_reset_L. was there before i replaced the q7085. did replacing the q7085 fry out the isl or something after it got voltage? trying to figure out if it was something i did or if it was because something fried after i fixed the q7085. any thoughts? ( Duke, this is the board i was asking about smc bypass fan spin on and you were right about the sense resistors they did not look good and i changed them out but it seemed it was the q7085 that was holding everything down) now i feel like im starting back over lol
 

nate8organic

New member
it appears there is no pp3v42. i'm only getting 1.2v is there something that is likely to cause the power drain or could it be anything on the pp3v42 circuit? kinda weird how i replaced the fet and now pp3v42 is being drained.
 

nate8organic

New member
I Agree.
I didn't notice before but i'm actually getting 7.74v on pin 4 of the q7085 could this be a problem? i'm pretty sure i recall that pin being at 18v on other boards. i know everything there is on the g3h line so it should in no way affect the 3v42 circuit.

3v42 = .39 in diode mode, and that checks out good with the boards i have on hand to compare too.
 
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nate8organic

New member
eh okay i fixed the green light issue. for some reason r6990 was only giving out 2.3v, replaced it and the green lights back. no fan spin still and wile i was testing the r7020 voltage was solid and then started dropped down to 1v and i check the q7085 and it also drop all its power, still have power on pins 1-4 18.4v. what would cause this to happen? i do not know if the isl is good as it was pulled from a donor, can the isl possibly kill this? also i guess pin 4 of q7085 should be 7.4v when there is a power draw?

Testing a couple times here and i found that it actually holds 18v for maybe 10-20 seconds and then starts dropping. something opens and then it drains maybe? also i'm finding that it is not frying the q7085 fet. also the fan spins with the smc bypass.
 
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nate8organic

New member
measuring ppG3H res to gnd is .43 and im getting .46 on a working board. is this a semi short or is that still within range? G3H is also dropping at the same time.
 

nate8organic

New member
i also have a good 12v on G3H when i have the battery connected but if i press the power button it drops to 2v ish. if battery and power supply are connected i get 12.4 to 4v back to 4v very fast on the G3H
also on the r7020 im getting 2v when it trys to power on. when the power supply + battery r connected i get 18.3v on the r7020 when its try to power up.
 

nate8organic

New member
if i pull of r7020 the voltage does not drop on q7085 and pin 1 of the R7020 is only .9v so im thinking something on PPDCIN_G3H_CHGR?
 

aprendiz

Moderator
Diode mode on PPDCIN_G3H_CHGR??? Also check your soldering job, other thing, you should go reducing variables not adding them, buy a spool of new ISL6259!!!
 

nate8organic

New member
yes q7030 appeared to be fucked on this board, after i replaced it i got 12v on ppbus and 18v solid on r7020 but i was not getting anything on pin 4 of q7035 so i replaced the isl and then everything was gone again, that was last night so i'm going to mess with it after i get to some other boards for the day to see what happened. i even replaced the isl back out with the other one and it had made no change i'm thinking c7035 or 36 might have died.

on a dif board with the same issues, i got it to give 12.34v jumping around 11v back and forth after i replaced the c7036 and voltage on r7020 and q7030 and q7035 have varying but consistent voltage now, how ever i do notice that randomly the voltages will drop to 0 and then it starts back up and everything's at 12v again. pin 4 of the q7035 is 3v then 0v back and forth. if i plug in the battery it does not charge. and i notice the green light randomly blinks. the other board i fixed it to the same point and then i changed the isl and it was back to where i started, so this time i'm going to wait for any ideas before i go fucking with anything at this point. i hate making progress and then starting back over because something dies again lol.

i started reading the datasheet but i have not finished reading it. i will do so now.
 
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