Never worked on a DLP but failing electrolytic capacitors in the power supply or something with the lamp,lamp circuit or another circuit comes to mind .So we have a 52" LG DLP. ( 52SZ8D-UA)
We bought it second hand last October and it only needed a new lamp. $100 and we were up and rockin with a new TV for our kids play room!
It has been working flawlessly for the last 5 months.
In the last couple weeks whenever we turn it on, it will turn itself off after about 10-20 minutes.
The picture looks fine, there are no warning lights on, no clicking or cracking sounds, everything is as it should be.
If you wait about 2 minutes after it turns itself off, it will automatically turn itself back on.
Many times it will be perfectly fine and the kids can watch it for a few hours with no further issue, sometimes it will turn itself off one more time and go through the same cycle.
Each time when it turns on, the power indicator light flashes yellow 10-12 times and then goes green and the tv comes on as normal.
You hear the colour wheel or fans spin up and hear no other odd sounds.
As far as I know, this is the sets second lamp. And it is nearing 9 yrs old, but was not used for a few years after the first lamp went out.
We replaced the original lamp with a Phillips, and it is still under warranty for another month, so if it is possibly the lamp I'd like to figure that out now rather than later
Lots of stuff about this on Google and You Tube : https://www.google.com/search?q=dlp....15455j0j7&sourceid=chrome&es_sm=122&ie=UTF-8