TechKnight, your explanation is logical and plausible. And if one analyzes the Sweep circuit and cannot conclude that it would in any way interfere (e.g., through feedback, noise, etc.) the Disk Drive circuit, or visa versa, then a single +12v PSU output with a 3.35A rating (or higher) should work fine. All that's left is an actual Se/30 test, to determine if our theoretical matches the experimental. All 3 of the "MEAN WELL" PSU's I mentioned before satisfy the output requirements.