Blaupunkt Munchen RD104 Car Radio/CD powering itself down

[Bladerunner_uk]

Hi, I have just purchased a boat which has a Blaupunkt Munchen RD104 radio CD (Keycard) fitted. It works fine but after one hour bleeps and switches itself off almost as if its utilising a "sleep mode". Pressing the power button switches it back on (radio or CD) but always again switches itself off after about an hour. The user and installation manuals dont seem to refer to this problem. Any suggestions ?