Thomas
Member
This 820-3478 Logic Board I have will not display to an external monitor. After further inspection of the Logic Board under the microscope I noticed U3015 to have a dark spot, it looked burnt. I went ahead and desoldered U3015, I also desoldered U3020. When I test each pad under those chips there is a short on two separate lines.
First short under U3015, PP1V05_TBTLC, Probe:1072.
Second short under U3020, PP1V05-S0, Probe:600.
When I inject 1V onto PP1V05_TBTLC, Probe:1072, U2800 heats up in the corner of the chip.
When I inject 1V onto PP1V05-S0, Probe:600, U1100 heats up.
Overall the machine works fine if you're not using an external monitor at all. I have already replaced this Logic Board for the customer and now I have this one sitting around, just trying to get it to work 100% again.
I plan to desolder U2800 and U1100 to see if the shorts go away, if they do go away I will replace the chips with working ones and will also solder on working U3020 & U3015. I can source a U1100/SR176 however I am having a hard time sourcing U2800/CACTUSRIDGE4C to attempt/complete this repair. Can anyone help me with sourcing a U2800? Also, am I on the right track?
First short under U3015, PP1V05_TBTLC, Probe:1072.
Second short under U3020, PP1V05-S0, Probe:600.
When I inject 1V onto PP1V05_TBTLC, Probe:1072, U2800 heats up in the corner of the chip.
When I inject 1V onto PP1V05-S0, Probe:600, U1100 heats up.
Overall the machine works fine if you're not using an external monitor at all. I have already replaced this Logic Board for the customer and now I have this one sitting around, just trying to get it to work 100% again.
I plan to desolder U2800 and U1100 to see if the shorts go away, if they do go away I will replace the chips with working ones and will also solder on working U3020 & U3015. I can source a U1100/SR176 however I am having a hard time sourcing U2800/CACTUSRIDGE4C to attempt/complete this repair. Can anyone help me with sourcing a U2800? Also, am I on the right track?
