Hello I have a hitachi

Question

Hello I have a hitachi 50v500 and the repair shop says it needs a power supply circuit where can I buy one of those they just put in a light engine 11 months ago which Hitachi covered the part but I paid the labor which was around 400.00 I do not want to spend anymore money like that to fix this tv they want now 552.00 for this repair and Hitachi will not help this time, this set is about 4 years old please can you help me