ARM CPU has no memory protection
This arm cpu has no MMU, so there is no memory protection at all. That means if you make a error, or run out of memory, the cpu will crash and you have to reboot the 558.
DP558 PSU diagram
Pictures of the PSU on different players
Fix some PSU problems
See here how some have solved their problems: http://www.mpcclub.com/modules.php?name=Forums&file=viewtopic&t=9183
Step by step guide to KISS DP-558 Power Supply Modification/Fix
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