Are there non-unscrewable microwave oven bulbs? [closed]

Question

I recently emptied a Samsung microwave oven of its components and came across the lightbulb, which appeared at first glance to be fitted in a diamond shaped holder.

Though when I looked through the glass at the inside of the socket it looked more glued than threaded, so I tried unscrewing it somewhat carefully so as not to accidentally shatter it in my hand. That didn't work. Pulling it has no effect either.

Are there microwave bulbs that simply don't unscrew?

I don't want to risk my hand by applying more force, and while my searches turn up matching photos on e.g. eBay, they have titles like "bulb & base" which doesn't tell me whether it's an actual threaded socket in the base or not.

If yes, why would you use a bulb like this? It's bound to break sooner or later. Is it just that much cheaper to skip the threads or is there another reason, like a justification for putting "no user serviceable parts inside" on the label?

Answer 1

It won't be a threaded socket. There will be wires emerging from the glass that are welded or soldered to the blades which are insert molded or staked into the base. The glass will be held in with cement, which you can see in the below photo (taken from Aliexpress):

There is no need to have two bases. Putting a screw base on the bulb would involve a similar amount of work and would be redundant. Microwave oven lamps don't typically spend that much time 'on' so the life may be deemed to be sufficient (I've never seen one fail, and newer ones are LED so it's unlikely I will).

If the leads are soldered (like the center pin on a screw base) you may be able to see them on the flat portion of the blades. Heating the bulb gently with a torch should soften the cement and allow you to remove the bulb itself if you can unsolder the leads. Yours appear to be soldered, based on those big lumps of solder we can see on the bottom.

I have done this with some weird dashboard lights that VDO used in a very old German car because the ones with the proper base (which twisted into a punched PCB with a kind of bayonet arrangement) were long lead time.