Mic works fine until warms up about 15 min then volume goes way way down

Fault in the main board. You have to replace the main board. As it's have SMD components is would be difficult to repair.
If you wish to get some more details then check the following link.
http://electro-medical.blogspot.com/

Try turning the volume all the way down then power the TV an see how
long it takes to bring a screen up if you still hear a popping sound then you have a bad part with a bad connection most likey a lamp and wiring.
Call to have it serviced a must if so.

Such a long delay and a slow return to volume is puzzling. If the return came back in say 30 seconds, I would suspect 1/2 of the V1 tube (12AX7) might have a failure of the heater. When it has failed see if this tube has TWO points of light in it. The cooling down and warm up would give a 15 second ramp up or down in volume. This tube has a path around it that would sustain a very low volume. Try swapping one of the other 12AX7's into this spot. If the sound totally goes away replace the one that was in V1 at first place and see if problem goes away.

check the remote control, take the batteries out and try to adjust the volume on the tv set itself.
If this resolves the problem the button on the remote may be sticking, either clear it or get a universal remote.

If you still have the problem without the remote then its time to take the tv to a repair shop or claim on a warranty.

prima lv-3228p lcd tv-after 15 mins of play the screen goes funny and there is still volume but the remote will not function. you cannot even shut the unit off, only by disconnecting the power supply. If you wait 15 -20 mins and plug the unit back in it will work for approx 15 mins again- then it will start acting up again?/

it probablt needs power supply capacitors, if you can take it apart and inspect the power supply, the bad capacitors usually are expanded and have a bulge at the top, you would need to solder these parts in, so some skill is required.

Try resetting the unit.
Make sure there is no disc in the unit. With the unit on, go to the front panel and look for the STOP (square) button.
Hold it down until the unit shuts off by itself. Turn it back on it shoudl work fine.

sounds like the head bolts maybe lose just check that first

Check fuel feed is ok and fuel pump pressure also check cold start injector could be running on this til warm.

This is a case of one or more transistors breaking down when heated. This can be found usually by using freeze spray to cool down one transistor at a time until the problem clears up. You can narrow this down a bit by determining whether this "noise" is effecgted by the volume control or not. Also, does the problem show up faster when the unit plays louder?

Dan