Proper resistor(s) for limiting LED brightness

I have an LED powered by a serial(Rs-232) port on my PVR. The light is connected to the DTR pin through a 1k$$\\Omega\$$ resistor. It is set up this way in accordance with the instructions for the software controlling the light. However, I find the light to be too bright and am wondering what the best approach would be to dim the light's brightness. I am not overly experienced in the field of LEDs, resistors, and diodes, but I am assuming a larger resistor (or set of resistors) or diode would drop the current, reducing the brightness. I just do not know which size resistor(s) or diodes to use. I cannot provide specifications for the LED itself, as it is a part from an old set-top box without documentation.

• Yes, either replace the resistor with a larger one or else insert another resistor in series (cut a wire somewhere and connect the ends via the added resistor.) Since you don't know much by way of details, there is no way to quantify a value for you. But if you insert another $1\:\text{k}\Omega$ resistor in-series, then you will get close to half the current in the LED. That might be a start in working out the better value. – jonk Apr 25 at 19:41
• Possible duplicate of Can I use blue-green LEDs as MCU state indicators on 3.3 V power? – Ale..chenski Apr 25 at 19:58
• If the brightness is really annoying, go with around 5k or as jonk says add 1k for just a little less brightness – Tony Stewart Sunnyskyguy EE75 Apr 30 at 22:19