This morning I did a little investigation regarding the USB2DB15.
I checked it with my older HAS units, it worked just fine. Tried with the V5.0 - all inputs appear grounded, the adapter doesn't work.
I supplied power to the USB2DB15 via the DB15, but didn't connect it to any supergun or PCB game - it also didn't work, the LED wouldn't light up.
I opened the adapter and checked the voltages. The 3V3 regulator wouldn't get power.. so I checked the 2SA1213 transistor and found something weird:
Emitter - 0.05V
Collector - 5.14V
Base - 4.93V
How can you get voltage on the collector if there's no voltage on the emitter and the base is so high?
I checked the USB2DB15 schematic, voltage regulator/transistor datasheet, and board layout, and found the culprit:
If you look closely, the collector and emitter of the 2SA1213 are swapped places! The PCB uses an incorrect part library.
So why does the USB2DB15 work with older superguns, or at all? Because of the parasitic power supply effect. During startup, the USB2DB15 drains current from the JAMMA PCB game button inputs, just enough to power on the S-816 voltage regulator, which then saturates the 2SA1213 transistor. This way the whole USB2DB15 circuit is powered on.
Since the HAS V5.0 buffers all button lines, the DB15 inputs use 20-30K pull-ups. There's no way for the USB2DB15 to drain anything from such inputs, so it cannot start. Buttons appear grounded.
To confirm and test this for yourself, power on your supergun+USB2DB15 without any PCB game connected. The adapter won't turn on. Add a 1K pull-up resistor on whatever button output of the USB2DB15 to mimic the PCB game's button input - it will turn on just fine.
There are a few problems with this:
a) The USB2DB15 drains current from your PCB game's button inputs during startup. First of all, you don't want this to happen at all. Secondly, it can also cause damage to the microcontroller on the USB2DB15.
b) The collector and emitter are swapped places, so when the adapter turns on, the collector (output in this case) is shorted with the main 5V line.
@Raph_friend was made aware of the situation and I'm sure he will find a solution.
To HAS users (all versions), I don't recommend using the USB2DB15 until this is sorted.