Defective product. Engineer was actually shocked as a result of defect in product. Evaluation/safety issues: unit under test uut. 1. 120 volts ac on phono plug connector for led pads. Problem: power switch is touching transformer secondary. During assembly, if heat shrink (insulating layer) is punctured, then ac power from the power switch is connected to center tap of transformer secondary. This puts voltage from the wall outlet directly into the electrical connections for the led pads. Test: to test for this problem, use an ac meter to read 120vac between phono plug and safety ground. 2. Safety ground is not connected to case of uut. Problem: in assembly, the safety ground lead in the ac power cord was not connected to the uut case. 3. Uut is not using a "medical isolation" transformer. 4. Brass machine screws holding case together are too long. One of four, half inch brass screws is within 1/16 inch of phono plug which could short against phono plug.