Mackie Studio Monitors HR624 MK1 – no power or wont stay on.
These great little monitors suffer from a regular power failure problem where they will not turn on. Not always, but quite often, this is actually a fault with the standby circuit which shuts the amp off as it thinks the input signal is too low. 
The solution is remarkably simple and just involves the replacement of a few capacitors. If you think you might be affected by this issue get in touch as amp repair is less than you think. Individual amps cost 1.5 hours time and a pair can be done for 2.5 hours + postage.
Best thing is to remove the amp from the cabinet by undoing the 8 torx screws on the back and packing the amp up and sending it in to me.