I recently bought an SQ5 and borrowed an AR2412 from a friend to use on a larger job. He warned me that it sometimes “takes 20 minutes to boot up”, and one time he actually had to relocate the console to the stage and mix from there. At first, it worked fine for me, powered right up and connected to the SQ5, no problem. During testing later on it failed, with the same symptoms others have mentioned, no lights on the front or back but the fan was running. It’s about four years old, so well out of warranty, and my friend said to open it up and see what you find.
Fortunately once I got it apart (a lot of screws!), it was still malfunctioning, and I was able to test PSU voltages. ±15 and +48 were all there, but nothing on the +10V rail, which also feeds the blue LED on the back. That ruled out the primary side of the PSU, and nothing appeared to be bulged or burnt with the components for the +10V part of the supply. There was continuity all the way from the cathode of the rectifier diode to the output, but I reheated all the connections, partially reassembled it, and tried it again. This time the 10V was solid and seems to be staying that way. Although I couldn’t see anything that looked like a cold joint, I think there was one and reflowing the connections has fixed it for now.
I didn’t get into any of the circuit boards on the front panel, but I suspect the +10V gets regulated down to +5V for all the digital circuits there.
A word of caution: This is a switch mode power supply. It is connected directly to the AC line, and there are voltages in there that can KILL you. The main electrolytic capacitor has about 170 volts on it, and there will be twice that if you’re in 230V land. It’s a place only an experienced electronics tech should be poking around, not an enthusiastic DIYer.
Geoff
