I wonder if anyone has seen any HID fixture outside of anyone's collection that got an LED retrofit only to be later converted back to its original HID light source such as a corncobbed metal halide fixture that got converted back to metal halide after the LED corncob lamp failed.

No, but I've seen a Cooper Vanguard HPS replaced with an AEL Watch Light, only for a few days and replaced back with another Vanguard HPS. Presumably the LED unit failed, and I imagine it was strobing but I didn't see it at night. It was too long ago and I don't know the people who rent the light enough to ask but I found it interesting.

I wonder if anyone has seen any HID fixture outside of anyone's collection that got an LED retrofit only to be later converted back to its original HID light source such as a corncobbed metal halide fixture that got converted back to metal halide after the LED corncob lamp failed.

I've seen a Cooper Lighting CLS XS40 floodlight that was originally 400w HPS corn-cobbed, but later the entire fixture was replaced with LED. Unfortunately, I wasn't there during the replacement and couldn't get the fixture. It seems like if a corn-cob burns out in an HID fixture, the whole fixture is replaced. Instead of using made in China corn lamp rubbish, use a coated LED filament lamp that can retrofit the luminaire. In Japan, there are BT-shape coated LED lamps. They are already making low wattage replacement lamps, but they make higher wattage lamps convex-shape. Both types reduce glare compared to an LED cob lamp or LED fixture. Only problem is they are expensive. They do make a lot of these lamps in many color temperatures though: 2100K, 2700K, 3000K, 4000K, 5000K and possibly more. Last of all, why not use coated LED filament lamps? (if they even exist).

Coated BT-shape LED lamps See here:https://www.eye.co.jp/lighting/sources/led/Lamp_G.html

Cobrahead convex retrofit lamps See here: https://denki.tss-shop.com/products/LDFS50L-G-E39D-721

No, they're either relamped with another LED, or replaced.
And another thing...they're not corn cobs...marketing "geniuses" came up with that. These are just COB lamps (chip-on-board).

I think I first saw the corn cob name on sites like eBay or Aliexpress but I guess the name eventually was used to describe all LED screw in lamps in that shape with exposed diodes. Ironically most corn cob LED lamps I've seen use individual SMD (surface mount diode) LEDs instead of COB LED chips that contain multiple diodes per chip.


In pretty much all cases I've seen where someone reverted back to HID from LED, the luminaire was swapped with a new HID luminaire instead.