Really stumped with this one and hoping someone can give some insight on what to check next:
1. 820-01041 2.9/16/512 board that we are upgrading the RAM on to 32GB.
2. Replaced 16GB Micron set with 32GB Hynix set and adjusted the RAMCFG strap resistors accordingly. We pulled the 32GB set from an identical board that had 32GB RAM (820-01041 2.9/32/512). We reballed the chips ourselves (twice!) and results were the same.
3. Unit powers fine and draws normal power, but does not chime or boot (and no charge tone when connecting charger).
4. Unit restores fine via DFU in a normal manner; no funkiness like hanging or anything like that. Restores to padlock, but unit doesn't chime or boot.
5. We replaced the original 16GB of RAM (and re-configured the RAMCFG straps) and board worked perfectly. It would boot, chime, install MacOS, restore via DFU, etc., all without issues.
6. We tried a SECOND SET of 32GB RAM (Hynix) pulled from another identical board (01041 2.9/32/512) and the issue is *exactly the same*. So, there's clearly some issue with configuring the board post-install of the RAM chips.
7. We scoured the board and it matches an identical board; CFG resistors all match, but board does not chime or boot.
Is there something obvious that we are missing here? We've upgraded RAM on tons of boards, but this is the first one that's given us an issue. I thought possibly the PCH or CPU had been damaged from heat, but we confirmed that's not the case by reinstalling original 16GB RAM set (and board worked well).
Any ideas where to go next? Thanks in advance for any help.
1. 820-01041 2.9/16/512 board that we are upgrading the RAM on to 32GB.
2. Replaced 16GB Micron set with 32GB Hynix set and adjusted the RAMCFG strap resistors accordingly. We pulled the 32GB set from an identical board that had 32GB RAM (820-01041 2.9/32/512). We reballed the chips ourselves (twice!) and results were the same.
3. Unit powers fine and draws normal power, but does not chime or boot (and no charge tone when connecting charger).
4. Unit restores fine via DFU in a normal manner; no funkiness like hanging or anything like that. Restores to padlock, but unit doesn't chime or boot.
5. We replaced the original 16GB of RAM (and re-configured the RAMCFG straps) and board worked perfectly. It would boot, chime, install MacOS, restore via DFU, etc., all without issues.
6. We tried a SECOND SET of 32GB RAM (Hynix) pulled from another identical board (01041 2.9/32/512) and the issue is *exactly the same*. So, there's clearly some issue with configuring the board post-install of the RAM chips.
7. We scoured the board and it matches an identical board; CFG resistors all match, but board does not chime or boot.
Is there something obvious that we are missing here? We've upgraded RAM on tons of boards, but this is the first one that's given us an issue. I thought possibly the PCH or CPU had been damaged from heat, but we confirmed that's not the case by reinstalling original 16GB RAM set (and board worked well).
Any ideas where to go next? Thanks in advance for any help.
Comment