Thanks for trying it out! So my math says that's 18 ohms, which should draw 277 mA from the supply assuming everything else is zero resistance. You're seeing a drop to 4.1 - 4.2V? That's pretty significant, although 277 mA is a bigger load then you're likely to see in reality (I think Floppy Emu is like 150 mA). Does it change if you wiggle the connector around, to get more contact between the corner of that square pin and the round socket?