Is there a way to turn off the mining aspect on an original Apollo btc miner and just use it as a node?
Yes, you can stop the miner in the GUI and the node will continue to run
GUI options:
1 on the miner screen at the top hit stop miner
2 hit the power button top right and select stop miner
SSH options:
1 sudo systemctl stop apollo-miner.service
2 If you want to make it permanent after stopping the service sudo systemctl disable apollo-miner.service