Luxman 507ux - AC Inlet Mistake

 It's hard to post when you think you've caught a brand like Luxman in a simple engineering mistake, but since getting in touch with them seems overly complicated I'm just going to blog about it and hope some one in the Internet knows someone at Luxman like CEO Tatsuya Sueyoshi and can have them reply.

The issue that I'm pretty sure of is that for the US, at least, the wiring harness from the AC inlet to the main power board causes the wrong side to be fused. 

In the US, only one of the 2 AC prongs has voltage, it's called the line.  The other is called the neutral. We typically fuse the line, the idea being that if a fuse blows the minimum amount of circuits still have power applied.  If we do the opposite (as in the case here) and fuse the neutral then much more of the circuits and the contacts and PCB traces will have lethal voltages.  If the fuse must blow, best to minimize the danger in the circuit.

In the US, line is black or red and neutral is white.  Now lets take a look at the curious Luxman inlet assembly.  It's clearly intended to be used with a variety of plugs.  What makes it curious is that it's nearly impossible to remove intact without serious chassis disassembly.  Anyway, take a look at a US variant:

The pin on the left is the line (hot).  You'll noticed above it are the vestiges of a fuse holder.  That makes sense as the line is what should be fused.  Not the neutral. Note that the fuse holder was not actually assembled when this assembly was removed. 

Let's flip this around to see the start of the issue: 

It's hard to read but the wire connectors are labeled BLK and WHT, from left to right.  Well, sure that's opposite the US color codes, but the real problem isn't here.  The real problem is on the power board, where the BLACK conductor is fused. 

You can see it under the mini black transformer in the middle on the right.  The black wire connects directly to the two fuses next to the plug for the black and white wires.  That would be correct using US color coding, but wrong because the BLK labeling on the PCB is to neutral. 

In case you are wondering, yes, the actual construction followed the wiring.  The picture below is from underneath so you'll have to flip this around in your mind: 

Solutions

While Luxman could easily correct this in the factory, there's not very good or easy solutions in the US because disassembly is pretty difficult.  The PCB is wider than the hole for the IEC inlet, so we can't just pull the whole thing out.  The inlet uses large, thick metal pins which are soldered onto the PCB.  The large pins make desoldering extremely difficult.  Those big metal pins act as heat sinks and practically prevent you from melting the solder before you melt the inlet.