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820-3024 - PPBus_G3H fluctuating. NSFW warning.

gcain

gcain

New member
Board had a little corrosion; refer to attachment. :eek:
After an ultrasonic, some flux, another ultrasonic and a stint in the oven it turned on and chimed, then switched off.

Now it spins the fans for a second or two, then turns off for a second or two, then on, then off etc. Eventually it slows down to just twitching the fans every few moments.

@ J6900 DCIN fluctuates from 16.28 - 16.80.
F7030 goes from 13.9v to ~3v, then back up.

C7200::1 goes from 13.9v to about 3.6v and back again.
 

Attachments

  • 20170419_121850.jpg
    20170419_121850.jpg
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gcain

gcain

New member
PP3v42_G3H is stable.

U7000::17/18 = OL
U7000::27/28 = 20ohms

U2700 looked okay going by the photos I took.

R7050 is measuring almost 0ohms. (Whats the correct way to measure a current sensing resistor like this?)
R7051 is 3Mohm (nothing wrong there...)
R7052 is 0.1ohm

R7051 is obviously blown, but C7050 looks pretty suspect too; will replace both and report back.
 
gcain

gcain

New member
Now I get no fan spin and F7040 is going as log as 1.8v.

Clearly I am on the right track, I can see now that it's cleaner a few traces are burnt / corroded away.

Will sort them next.
 
gcain

gcain

New member
U7000 is getting really hot then it goes cools down for a second or two then gets hot again.

Should I replace it, or is this caused by an issue somewhere else?
 
gcain

gcain

New member
OK will swap it out then.

I was wondering if it was trying to supply enough current to a capacitor that was shorting and giving up after a bit; then trying again.

Will swap it and report back.
 
gcain

gcain

New member
Thanks for the extra info.

I swapped U7000, turned it on and something went SNAP, but I'm not sure what or where yet. :/

Might be too much wrong with this board after all...
 
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