Loud noise like tray vibrating. does not cook.

If and when an oven is coming on or doing anything by itself, this is very dangerous and can result in a fire.

So until it is repaired, please leave it unplugged or leave the door open when it's not in use, and of course one should never leave a microwave unattended while cooking.
Please post a new help request here on FixYa and include the full model number from the tag in the cooking cavity or elsewhere on the microwave, such as the door frame, controller frame, etc. and detailed symptoms and when they occur.

see this causes and fix it. God bless you
Magnetron If the microwave is loud or noisy only when cooking, the magnetron tube might be defective. The magnetron uses high voltage, high current DC power to generate the microwave frequency that cooks the food. Under normal circumstances the magnetron is nearly silent. However if it is damaged or nearly burned out it can begin emitting high pitched or growling noises. It's not normally dangerous to use a microwave oven when it makes these noises, but they are an indication that the magnetron is almost dead and will need to be replaced.
Exhaust Fan Motor If the microwave is loud when running the fan motor might be
Stirrer Motor If the microwave is loud or noisy the stirrer motor might be worn out. The stirrer is a metal blade which slowly turns around, deflecting the microwave energy in a random pattern inside the microwave oven. As the motor nears the end of its useful life it begins to make grinding noises. The microwave will not heat food evenly without this stirrer, the motor should be replaced.
Turntable Motor If the microwave is loud or noisy the turntable motor might be worn out. This is a common problem and relatively easy to replace.

The exhaust fan may be loose, {check mounts} also, the turnable motor that rotates the plate often gets noisey before seizing, {remove plate to see if noise goes away} and finally the magnetron gets very loud near end of life.

The fan could have an obstuction. I have heard of tech sheets getting into the fan and causing a vibration and vibrating sound.

Clean well the inside of the oven, if you keep having the problem and the inside is clean, then the magnetron is starting to go.

You either have a bad magnetron tube (5 or 10 year parts warranty item through GE Factory Service 1-800-432-2737 or www.geappliances.com) or a shorted high voltage rectifier. I think the light being out is a secondary problem.

I would recommend changing the diodes as well. This will usually take care of the problem.

If you mean a loud buzz that cuts on and off as the oven works, it is probably the outer metal cover vibrating as the magnetron powers up and down. Try holding/ pushing/ poking the metal cover while the oven is working, if the noise abates or goes away, this is the problem.
You may get relief by simply tightening the screws securing the cover, if not, maybe a little careful insertion of a thin strip of cardboard or similar, at the point the vibration occurs, may dampen it. Good luck.

In order to try to set your mind at ease I will have to explain the Basics on how a Microwave Oven Functions.
When a Microwave Oven is set to COOK ...START. It cooks at 100%. There is no lowering of the heat as with a Range ( Cook Top) Control. So in order to do the other things such as DEFROST, WARM, or anything other than 100% COOK. A COOK ON- COOK OFF system was utilized. To DEFROST, the Microve COOKS at 100% for 30% of the TIME, then IDLES for 70% of the TIME. COOK ON 30% of the TIME, COOK OFF 70% of the TIME = DEFROST This is why you can hear the CYCLE. More power is required during the ON CYCLE, thus the lower vibration. The Vibration occurs when the High Voltage Transformer is turned ON ( COOK ON).
The VIBRATION seems to have got louder with age. This is somewhat normal as there is a vibration from the High Voltage Transformer present every time the Microwave is used. screws and other metal parts seem to get loose with this vibration. There is no solution, unless you can tighten EVERY screw, nut, and bolt in the unit.
Sorry!

Sounds like you just fried your magnetron. Normally when they go bad, they make a very loud noise like what you described. The smell concerns me because you may have ruined the waveguide as well. If the magnetron burns through the protective painted surface of the waveguide, the waveguide is ruined. In most microwave ovens this means replacing the entire unit because the waveguide is not replaceable. Putting a new magnetron in a damaged waveguide will result in the same arcing and eventual failure. In addition to the magnetron, the following components are part of the same high voltage network: HV Transformer HV Diode HV Capacitor Magnetron Thermal Cut-Out Any one of these components could have also been damaged. I DO NOT recommend taking any voltage measurements inside the HV network. Potentials of over 4000 volts can be reached and make it very dangerous for the do-it-yourselfer. Taking resistance readings with the unit unplugged is strongly encouraged. If you decide to pursue a repair, inspect the magnetron tip and inside of the waveguide first. If the magnetron is melted and/or there are burn marks inside the waveguide, a new microwave may be a in order. This actually may be a better option than an expensive repair. I hope you find this advice helpful.