Chosen Solution
Hi everyone.. and specially @refectio SIR :) I have an iphone 7 with vddmain short. The phone story is very normal, client said, he just put out the phone from his pocket and find it off. I check it with DCPW, they show. 1,2 Volt and 1.4 Amp. (my DCPS voltage down automatically when i connect short phone and it i manually up the voltagage button, nothing happen and remain same. The back lower part is hot. The hottest ic is q2101 and Tigris u2101. I put out both of them and check the short present. i change both ic’s but short remain. Usually i check with Freez spray and always find the bad capicitor or ic, but in this case i cant find nothing strange. Anybody has a suggestion plz? Thanks
Hello AGS. It’s normal for Tigris and Q2101 to be hot as that is where all the current flows once VDD_MAIN has been “created”. The best way to find a short on VDD_MAIN is to “inject” 4.2V directly on VDD_MAIN. There’s a nice test point directly on the board, near the Home Button connector that you can solder a thin wire to. Then look for a heat signature. While the back and lower part of the board is warm, it may be a red herring (a false lead) leading you to believe the problem is there. Check all the areas that have VDD_MAIN present (use ZXW to find these areas). For example, remove the CPU shield and freeze that part of the board to see if anything (perhaps C1910 if you have an Intel board) heats up first. Freeze spray usually requires several attempts, focussing on one part of the board at a time. Jessa did a great video on Freeze Spray vs Thermal Camera, you should check it out.
