I have an old mac g4 400mhz running OS 9.1. It has a huge 20inch display (like an old tube TV) which is very heavy with a broken stand. It has the ADC (apple display connector) that is powered by the tower. I purchased a 23" cinema display with the identical connector from ebay. When I connect it to the serial port the system immediately powers up and the screen lights up for a few seconds then goes dark. The power light remains on and pulsates but the screen is dark. I plugged in the old monitor and it powers up and shines bright - no issues. Can I assume the display I bought is faulty or is there another reason this 23" display won't work? (i.e OS, needs adapter, etc) Help!!!