george-a
Member
Hi guys,
Having UC this one (was pretty messed up) I replaced U6990 and got a green light (at least thats how I remember it and in a hurry noted on paper - since this board was written off for a couple of months) but the system is still dead.
Measuring around I discovered that my ppbus_g3h was 1,2V, measured around a bit more and I decided to replace the isl6259 which brought the ppbus_g3h to 4,12V (I should have kept measuring as you ll read further down).
L6995 measures 0,070 in diode mode but when removed the right side (pin1) measures 0,58x. I thought maybe there is a short somewhere and I applied 1V as per Louis (http://advancedreworks.com/forum/arc...hp/t-1476.html) on the 0,070 side (brain activity has considerably slowed down by now) but nothing gets really hot and thats expected from a few milliamps draw.
EDIT: as per this thread: "https://www.rossmanngroup.com/boards/forum/board-repair-troubleshooting/1013-mbp-820-2936-with-short-to-ground-on-pp3v42_g3h-and-no-orange-or-green-light" I must inject 3.4V which also makes sense - will do this and come back soon. Please read on...
F7040 diode mode is 0,434.
Finally a few minutes ago I just measured short (diode mode 000) at pin2 of ALL THREE L7510, L7520, L7550 (raised one side from the pad with the soldering iron). Is the CPU fried? Should I inject voltage here?
Should I just name this sucker "donor"?
Thanks for any input guys.
George
Having UC this one (was pretty messed up) I replaced U6990 and got a green light (at least thats how I remember it and in a hurry noted on paper - since this board was written off for a couple of months) but the system is still dead.
Measuring around I discovered that my ppbus_g3h was 1,2V, measured around a bit more and I decided to replace the isl6259 which brought the ppbus_g3h to 4,12V (I should have kept measuring as you ll read further down).
L6995 measures 0,070 in diode mode but when removed the right side (pin1) measures 0,58x. I thought maybe there is a short somewhere and I applied 1V as per Louis (http://advancedreworks.com/forum/arc...hp/t-1476.html) on the 0,070 side (brain activity has considerably slowed down by now) but nothing gets really hot and thats expected from a few milliamps draw.
EDIT: as per this thread: "https://www.rossmanngroup.com/boards/forum/board-repair-troubleshooting/1013-mbp-820-2936-with-short-to-ground-on-pp3v42_g3h-and-no-orange-or-green-light" I must inject 3.4V which also makes sense - will do this and come back soon. Please read on...
F7040 diode mode is 0,434.
Finally a few minutes ago I just measured short (diode mode 000) at pin2 of ALL THREE L7510, L7520, L7550 (raised one side from the pad with the soldering iron). Is the CPU fried? Should I inject voltage here?
Should I just name this sucker "donor"?
Thanks for any input guys.
George
Last edited:
