How to Repair Dahua sd42212s-hn?

They don't see replacement parts.

Best bet is to try to find some nonworking ones on ebay cheap and swap out parts.

Or just buy a new camera LOL.
 
Most likely they don't have tiny belts there.
Just search online, most likely something will pop up.
 
I get my belts off ebay from China sellers. Even had to have some trimmed because the were just little wide. So bought again asked to make it 0.5mm thinner and got it. Because of pitch and other factors it would be best to know the belt text like mxl-xxx and tilt belts don't always match the pan belt so don't give them that number of other belt unless you want backup lol. Next no picture could be any number of things. Repairing a good few cameras had issues with a few different parts. Most my cameras repaired besides 1 were all in the camera module. The part found in the head. From QFN ethernet chip, smd ethernet transformer to sot-23 voltage Regulator so hard to say what you issue is. Also need to make a test cable for poe. Using only pins 1,2,3 and 6 wires. If you plug in and camera don't dance that can lead to bad wires in wiring or bad ethernet transformer. That could be one of 2 places haven't found both to be dead there is one in housing and one in module. Now that I think about it also had a light sensor be bad. And one with bad iris. In my subject camera runs lens but because of iris and different camera the sensor the camera fails so camera gets a shut down signal from camera and next step to turn on never happens and no ip would happen..