Working on an 820-01521 board that we replaced a dead CD3215 on, pretty standard. No issues were found after repairs. We stocked the board and recently pulled it to send to a customer, and noticed a very quirky issue that we've never seen before.
The only symptom is: When attempting to connect to WiFi pre-boot (i.e. to run AHT or to load Internet Recovery), after selecting the network and when entering the password, the board acts as if the keyboard is inputting characters--i.e. phantom registering--but it's not. The issue ONLY occurs at this time (SPI input presumably, before keyboard switches to a USB device). Once OS is loaded, there are absolutely no issues with keyboard/trackpad or WiFi.
Things we've already tried:
1. Have tried 3 different trackpad/cables and 3 known-good keyboards.
2. Have tried restoring T2 multiple times.
3. Have tried reinstalling MacOS multiple times.
4. Have tried 3 entirely-different test assemblies--different LCDs, batteries, audio/IO boards, TouchIDs, USB-C ports, etc--all different and all known-good.
5. Replaced keyboard/trackpad connector on board, as well as all related SPI controller circuitry for kbd/tpad (U6860/6865).
At this point, I'm suspecting a possible T2 issue. Before we worried about that, I wanted to see if anyone had any other ideas. This one has been so odd and I'm out of ideas of what else to try. I'm wondering if MAYBE U3000/low-volt USB circuitry could be related, maybe?? But I'd expect issues/symptoms beyond the one we're seeing. Very odd.
The only symptom is: When attempting to connect to WiFi pre-boot (i.e. to run AHT or to load Internet Recovery), after selecting the network and when entering the password, the board acts as if the keyboard is inputting characters--i.e. phantom registering--but it's not. The issue ONLY occurs at this time (SPI input presumably, before keyboard switches to a USB device). Once OS is loaded, there are absolutely no issues with keyboard/trackpad or WiFi.
Things we've already tried:
1. Have tried 3 different trackpad/cables and 3 known-good keyboards.
2. Have tried restoring T2 multiple times.
3. Have tried reinstalling MacOS multiple times.
4. Have tried 3 entirely-different test assemblies--different LCDs, batteries, audio/IO boards, TouchIDs, USB-C ports, etc--all different and all known-good.
5. Replaced keyboard/trackpad connector on board, as well as all related SPI controller circuitry for kbd/tpad (U6860/6865).
At this point, I'm suspecting a possible T2 issue. Before we worried about that, I wanted to see if anyone had any other ideas. This one has been so odd and I'm out of ideas of what else to try. I'm wondering if MAYBE U3000/low-volt USB circuitry could be related, maybe?? But I'd expect issues/symptoms beyond the one we're seeing. Very odd.
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