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Tech_Cowboy, your link leads to a ton of hardware info about the iriver, I didn't know that they were available. Thanks a lot! I went through the schematics, and I agree with you. If wrong polarity is used, chances are that the LTNP (harddisk power regulator) or the battery charger chip die. If too high a voltage is applied, the charger chip BQ24022 (AZU 3AW...) is a hot candidate. If the harddisk reg died, the iriver would still boot, but end up with a disk failure message or so. If the battery charger BQ... dies, it will have three options:
1) It shorts to ground. In that case, desoldering pin 10 and applying 3.7V from an external regulated power supply to the PCB pad of pin 10 should reanimate the iriver. If it works, the BQ... chip has to be replaced.
2) It opens. Not very probable because if that were the case, the iriver should still work, fed by its battery. However, the battery won't be charged anymore. But connecting the wrong AC adaptor wouldn't cause a sudden death.
3) It shorts in and out, bypassing the (too high) AC adaptor voltage directly to the board. That is what FETs usually do if run at overvoltage, and the BQ...chip uses FETs to supply the battery and the iriver. In that case, the caps will die, and maybe the battery as well.
Therfore I'd modify my repair instructions a bit. I would first detach pin 10 of the battery charger chip and check if the iriver can be operated from an ext. power supply. If yes, the chip has to be replaced. If this does not work, and if a lot of current is drawn from the external power supply, most probably one or several caps are fried. If the ext. power supply has an adjustable current limiter, the defective caps can be found by carefully increasing the current and checking the temperature of the caps. They must not get hot, not even warm.
The worst scenario is: The iriver draws little current, nothing gets hot, and it does not boot. In that case, the processor or one of the auxiliary chips are probably dead.
I guess a normally working iriver should draw about 100mA. The battery has a cap. of 1300mAh, and at 100mA it would provide 13h of operation.
Horst
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