On November 28, 2023 at 19:11, SysTech_Larry said...
If the original remote is IR, you can use an IR detector to view the button's command byte and header info. If your universal is set for the same device, you can use an EFC to reproduce said command byte.
I have a map that converts a command byte to an EFC for many devices and an alternative map for one exception that I found.
Larry, the OP has mx-850 remote, which made by Universal Remote-Control INC, only remotes made by UEI, which stands for Universal Electronic Inc, accept EFC's. This forum only deals in URC remotes. Yes, both companies use the prefix urc- in their remote model numbers, it doesn't mean they're the same company. Back the 1980's all remote brands use the moniker "universal remote control" so it couldn't be patented.