A few weeks ago, I got an old Antminer S1 for cheap, cause I was curious about BC mining. It's got an undervolt mod and does about 140 gh/s. Right now I started with mining on Slushpool. But I only make like 6$ a month. I didnt expect the miner to be this outdated. Or would updating my firmware maybe help?

Is mining altcoins an option? But there seem to be only  a few coins that use SHA256 hash.

Thanks for any help!