A device for tensioning a preform made from interlaced fibers is applied to tension the preform used in a process for fabricating a part made from a ceramic matrix composite material. The second cladding layer forms a stripe-shaped ridge on a side opposite from the substrate, and a first conductivity type current block layer is disposed on both sides of the ridge. The output voltage to drive the OLED panel load is supplied by the IBBC and the positive input of the OLED panel is tied into the input power supply of VIN directly without any switch. A second group of U-shaped tubes is provided with a first segment extending from the second supply header to the second end of the fin pack, and a second segment extending from the second end of the fin pack to the second return header, where the second plurality of U-shaped tubes is disposed inwardly of the first plurality of U-shaped tubes.