My hitachi 32ld8600 keep turning off after 4 minutes

try leaving off for about 15 minutes then turn back on may have a button battery for mrmory if so will need to remove for a couple minutes hand

There should be a short circuit at the main power supply regulator board. Check all the rectifier diodes and other components. Check the switching device for short. To get more details, http://electronicshelponline.blogspot.com/

I would start checking capacitors on the pcb's.

This set uses a number of green L.E.D.'s inside which are tied to different voltages---if you can watch them when set shuts off you are looking for one that goes out either quickly or after the others--points to area (voltage) where problem may be.

Other visual indications are screen changes red, green, blue right at shutdown and sound and brightness then both vanish=shutdown circuit being triggered to protect the set.

reset tv unplug one minute turn off main power plug in turn on main power try again, if not try different input and source ie dvd player or cable box

Replaced the lamp, the lamp code (Part Number) is on an orange tag on the side of your TV.

I just got done putting my panasonic 50 projection back together. There is a thermal cut off relay on top of your bulb box, can normally be seen after removing the back of the tv. With the tv unplugged make sure the area around this relay is clean of dust. If the simple fix dosn't work make sure your cooling fan is coming on with the tv.
Kevin

If you haven't done so, replace lamp part#XL2000U

Off the cuff it's about time for a new Tv... But give me the model number and I'll try my best.
Bill

possibly a bad power supply board.