Sandisk Clip Jam
This is relatively new (PCB designed and made in 2021, so just over two years old) but dead Sandisk Sansa Clip Jam mp3 player, 8 GB version.
The symptoms:
- not turning on, even if applying reset by holding "play" and "home" buttons together for 10 seconds
- consuming only 7 mA when connected to charger (thus not charging the battery), about 40 mA if volume down key was pressed same time
- USB device not detected by PC
Front button panel is easy to remove (few plastic latches), but it does not help with disassembling in any way.
While latches seem to be very tight and plastic seems brittle, I've actually had no problems with dissambly - starting with latch near the headphones jack - and
there was no visible damage after opening the case.
SDTNQFAMA-008G flash - SanDisk 19nm 64Gb MLC 16K 1Plane.
Cell was discharged (cut off by the protection circuit), but apparently not below critical 2.5V level.
Charging it externally and connecting back did not help with turning on issue though.
Action ATJ2127
H61 S08N 1104 - most likely FM radio receiver. Reception seems fine and RDS is working.
"test mode" pad might be interesting, but I haven't tried it.
As there were no signs of damage I've tried old trick with heating up flash chip and it worked, allowing to start the player. It was detected by PC and I was able to upgrade the firmware (actually just rewriting it as it was the newest version already). It still failed to start. I'm assuming that this could be data retention failure in boot area and boot is not updated by regular firmware upgrade. Despite that I've reheated flash two or three more times and left it turned on and charging/playing for a longer time. So far it turns on reliably, but it might be a fluke and I have no idea how long it would last. In an ideal world firmware should have some continuous, low-priority process scanning both boot area and firmware area for early, correctable bit errors and refresh the content of all blocks that have pages with correctable bit failures.
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