The projector cuts off immediately when turned on. The bulb is relatively new, maybe a couple of months old.

The plain 1950's era Argus 300
(see attached JPG)
has no fuse to blow.
Suggest using ohm meter to go from AC plug to bulb SOCKET's 2 contacts
{ meaning the CLS bulb's base (where the bulbs 2 side prongs engage)
as-well-as to the sockets bottom contact (for the bulb's bottom contact) }
w/lamp switch _ON_.
- AC plug -to- socket's base contact : ~5-ish ohms (goes thru wire nut)
- AC plug -to- sockets bottom contact : ~10-ish ohms (goes thru lamp switch)

If one is open maybe that one goes to the lamp switch & it's a bad switch.

But if switch is good & one is open ::
Maybe the bulb socket
(which has has 2 screws for the hot/neutral AC wires)
has a loose screw needing to be tightened.

And there is a single wire nut present,
maybe it needs to be tightened.

Regardless, the Argus 300 wiring is very simple.

Can't imagine it being oxide related, BUT if so DeoxIT D100L 25ml is an excellent contact cleaner.

This is a clear indication of a new bulb requirement

Ordered a new lamp at dealers cost ($140). Let's see if it was a malfunctioning bulb.

I think you'll need to buy a new bulb,

ballast is not striking the lamp and needs replacing

this worked for me what i did is: turn on projector then undo the light panel when its on the projector then will cut off, now the light panel pushes down on the hidden safety switch take a screw driver and push down on the switch, the projector will turn on then wait for about 8 sec then release the projector will turn off, repeat step several times until the light flickers, then do a couple more times and the light should come on and should stay steady turn off and let cool for 10 min, this worked for me hope it works for you!

I have a 3 yr old AE900U dont know exact hours but prob at least 2000 hrs. about every other start up, the projector would flash little box; (replace lamp now). now a month later lamp wont come on. So this is prob the normal way a lamp will die. anything else might be another problem.

I have the same issue. With a LP70. I upgraded the Firmware + USB Drivers and I still have t he problem. Basically as soon as a source is detected the Bulb turn off. Help!

This is known as 'cycling' and is common with mercury-vapor bulbs nearing end-of-life. When the bulb first starts, it glows dimly and grows in brillance. As the light grows, the pressure and temperature of the bulb also grows--increasing power demand. After a short while, the demand exceeds the ballast limit and the bulb extenguishes until the temperature (and pressure) drop again. Then, the cycle starts over. Bottom line: you need a new bulb (or, the correct bulb).

This is NOT a bulb problem unless your "lamp" LED is lit, which you say it is not. Many people have reported this problem with the Optoma 72. You can send it in for warranty service (it has a 2-year warranty) to get the lamp controller chip replaced, but the problem may recur. Optoma does not appear to have a permanent solution to this problem. My projector has broken exactly like yours TWICE in a year. I haven't even needed to replace the original bulb yet. :(