i bought its own 5v power supply of ebay
http://www.ebay.com/itm/5V-3A-DC-Universal-Regulated-Switching-Power-Supply-/390089280380?pt=LH_DefaultDomain_0&hash=item5ad3220b7c
had the same issue.....fixed it! i have a Vishay LEE 128G032 series
http://www.futureelectronics.com/en/technologies/semiconductors/optoelectronics/led-segment-displays/Pages/4668745-LEE-128G032-1.aspx?IM=0