820-2915 1/4 fan spin

Chuck60

Member
Hi I’ve checked all voltages and all are ok I’m pulsing at Q2830 pin 2 ENET_WAKE_L
I see it’s from u3900 which I believe is thunderbolt and I have corrosion around Q4260. So my question is where can I disable this u3900 to make sure the area is bringing the board down.

if I’m on the wrong Track please help before I derail:) thank you.
 

2informaticos

Administrator
Staff member
Why would you worry about that pulse, if all volatges are pulsing?
Did you check all big coils and voltages from pages 70/71?

Try first starting in SMC bypass mode.
 

Chuck60

Member
I’m sorry I meant that the other voyages aren’t pulsing Only ENET_WAKE_L. Which goes to the clock chip From q2830 I believe :(
 

2informaticos

Administrator
Staff member
Which voltages do you get on the board?
Or which ones pulse at least.
Fan cannot try to spin if 5V_S0 doesn't pulse...
 

Chuck60

Member
Well yes the 5v_s0 is pulsing the fan is on and off :( 12.56, 3v3, 5v but s0 is pulsing pp5v_s0 but I was thinking the clk circuit or thunderbolt had something to do about it.

Also how hard should it be to replace both USB ports? I’ve tried for like 10mins and couldn’t get it all the way off. I was gonna use my hot air but it was melting those 2 plastic bubbles near the back cover sensing thing.

I’m gonna go check what you told me and report back thank you
 

Chuck60

Member
pp3v3_s0, pp5v_s0 are pulsing. I’m sorry you where right.
PPVCORE_SO_CPU= 0v
ISNS_HS_COMPUTING=12.53v not pulsing

Q7830 has 3.3v on pins 1-3 and pin 4 is pulsing. The diode mode on pin 4 -.483
 

2informaticos

Administrator
Staff member
"Try first starting in SMC bypass mode."
???

Check for any shorted power rail from pages 70/71.
Also check if any big coil pulses, apart of CPU ones.
 

Chuck60

Member
Ok I changed clk chip and found shorted Cap pp1v8 rail that was making it come down. So now I’m all good except I removed two USB port that where really corroded. Where can I get these new? I’m trying not to use a donir as the usb won’t look new.
 

2informaticos

Administrator
Staff member
No idea really if you can get new USB ports as replacement.
Donor board should be good enough.
This machine has 9 years now; does anyone expect brilliant USB ports?
 

Chuck60

Member
I’m sorry I understand . But you know some people want it like factory :/ I do my best too please them. They’re not satisfied with a good working board everything must be spotless.

thanks again for you continued support
 
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