Replaced bulb and when I turned it on it made a small electrical noise and there is no picture. Projector is running and green light is on but no picture.

SOURCE: color problems

check out this thread: http://www.fixya.com/support/t138974-optoma_projector because there they say it's due to dust.

I'm having the same problems with my ep770, and am going to give it a try.

SOURCE: dvd10 optoma projector makes a loud noise

Hi, I'm not sure if it's the same problem I had..
I had it on picture mute, for maybe 15 mins, which may not have been a good idea. While it was muted, it made a sparking sound, and then a very loud grinding noise. When turned off, the lound noise stops, and the fan continues as usual for about a minute. As soon as it's turned back on, the grinding noise is back. But the logo seemed to display ok.

I took it in for repairs, and they said they needed to replace the color wheel to fix the problem.

optoma dv10 mode

SOURCE: Optoma hd65 projector new bulb wont turn on...cant reset timer!

I think it's a lamp driver issue from what I've seen others have gone through. I also read that if you go through the sequence of unplugging, plug back in, wait 20 seconds and try to turn on, multiple times, it will finally kick on and work. I just got mine to turn back on by doing this and waiting through the fan cycling without the light turning on. After the 4th sequence the light flickered. After the 7th sequence it finally turned on and is working. Now I can watch the Super Bowl and will look into replacing soon.