Using a LS248 7-segment driver, but segments are dim. Can't figure out why
The LS248 has an output that looks like this: 



It effectively has a (nominal) 2K resistor in series with the output when it is high, so your 150 ohm resistor adds to that, making it effectively 2.15K. 

To make this work with a minimum of muss (as well as a minimum of efficiency), add a pullup resistor to each output (Vcc to output) and omit the series resistor. Try about 470 ohms to stay within the ratings of the output, but you could go lower if you feel like abusing that antique chip to get a bit more light. It would be unwise to go below about 220 ohms, as that will make the 'off' current exceed 24mA per output.