Sorry to hear your trusted DLP rig blew a rod ;(.
IME even if you are handy with a soldering iron/schematics, you need to factor in the entire picture, including the additional warranty you would get by upgrading to a new technology HDTV (with much better PQ for less $$, btw). The quality of your $2500/ 7 yr old DLP has been superceded by many LED models for <$1K. Even if you can throw in $500 worth of parts yourself, there's no guarantee something else won't blow out (likely, actually IME- given the amount of issues you are describing). Purchasing a new HDTV + 5 yr extended warranty makes more sense IMNSHO. The vast majority of these devices are not intended to be repaired by the end user, even one with the correct electronics & tools (e.g. HDTV still won't boot although you have followed all instructions to the letter of the law...).
I have a 67" Samsung DLP TV that up untill recently has been a fantastic set. I.D. info is:
Model #: HL-T6756W
Model Code= HLT6756WX/XAA
Serial #: AJHJ3CKPB00068A
Mfd Date= November 2007
Version #: PF01
The malfunction started out simple- the lamp burnt out. Unfortunately, I bought a cheap third-party lamp and after installed everything worked fine for about 5-minutes. Then, a loud 'POP' was heard from inside the cabinet and the picture, audio and front panel lights went out. Upon removing the back panel I could smell burnt plastic and found a burn hole in the Ballast Unit. My theory was that the 'CHEAP' lamp caused a power surge or current spike that destroyed the ballast. I then procured the correct Samsung lamp (probably Phillips) and a new Ballast Unit plus a new lamp cooling fan. With these parts installed, the TV will not pass the initial start-up self-test and the system shuts down before any further damage is done stopping power from being sent to the lamp, etc. This shutdown occurs about 60 to 90 seconds after power is turned on.
Due to the earlier surge that killed the Ballast Unit and the new 3rd party lamp, I suspect that the Switch Mode Power Supply has now failed but I cannot find a schematic that gives pin out voltages that I could measure. I am trying to decide whether I should buy an entirely new Samsung Power Supply or procure a 'repair kit' offered by shopjimmy.com that provides all new capacitors and fuses. As a retired Avionics and Computer Engineer I am well-versed in the use of a soldering iron!
PLEASE HELP....has anyone experienced a similar problem? I need your opinion before I drop more money on parts. Nearly 7-years ago this rather large TV with a fantastically sharp NFL picture set me back $2500.00, so I would love to repair her... she has been most reliable until recently.