How to replace a tuner in a mitsubihi dlp tv?

Tuner is definitely no good.

That connection MAY be directly connected to the tuner module. Try this shop for parts:
TV Parts Universal TV Stands DLP Chips ShopJimmy

You'll need to replace the main tuner board. You can get it onlie from:
TV Parts Universal TV Stands DLP Chips ShopJimmy It's pretty easy to do yourself.

Follow the power cord inside to the power board--line fuse will be there--have fun and patience as a lot of screws to remove to get there---as seen from rear power board should be to far left side.

Set may have two tuners or a combined one (no model here) and average cost is well over 100 just for the part--it is soldered in.

IF the tuner is bad there is another option---if a DVD etc works via rear audio/video inputs you can route with a box signal in the same way to one of those inputs---bypass the tuner and use the box for signal and changing channels.

Google the model number of the set with "parts" if you want to try to locate the tuner or the entire board (may not be available).

Sorry its analogue only, why not just purchase an external digital tuner

I have the same model that had the same problem, all I had to do was clean the blue lens in the optical engine. looks great now. free fix.

Have the tuner signal board replaced. HDMI does not use the regular tuner bands, it is bypassed when using hd inputs.

Is this a Mitsubihi WDY52525 DLP set? First press the reset button and let the TV reset to see what happens. If still the same check all inputs to see if they all act the same (no pic/no sound) if they do then most likely the DM board is bad and will need to be replaced. I would suggest have a technician replace it for you.

There is no color chip. What it does have is called a motor driven color wheel. The problem is that the color wheel is no longer spinning to produce color. Replace the color wheel and you should be fine.