With a tv set it could be anything like capacitors, bad solder joints, relays, sleep timers, remote control circuitry problems, etc. I would suspect as likely culprits though would be capacitors and bad solder joints with caps as the number one suspect. Go to the newsgroup sci.electronics.repair and post your monitor's brand, model, and chassis number and one of the professional tv repair techs may have some tips for you to check out.