The datasheets show your 240 ohm resistors plus 10mA loads when more expensive LM117 and LM137 IC s are used. It says that LM317 and LM337 ICs should use 120 ohm resistors to prevent the output voltage from rising. Then the resistances of your pots must be half what you show.

 

The datasheets show your 240 ohm resistors plus 10mA loads when more expensive LM117 and LM137 IC s are used. It says that LM317 and LM337 ICs should use 120 ohm resistors to prevent the output voltage from rising. Then the resistances of your pots must be half what you show.

Yes, I know that the resistor has a different value from the datasheet. I've actually seen that it works with both 120 and 240R. Obviously the set value of RV1 and RV2 changes but this is not a problem as it is a trimmer.

 

Not all LM317 ICs work properly with the 240 ohm resistor that can be used with all more expensive LM117 ICs. Some LM317 ICs need the spec'd 10mA of load (the 1.25V reference/10mA= 125 ohms minimum for all of them). Therefore some of the LM317 ICs with a resistor higher than 125 ohms and with a low current load will not regulate and cause the output voltage to rise. Read about it in the datasheet. Maybe you are just lucky that yours work with the wrong resistor or maybe your LM317 ICs never had no load.

 

With light load it work so probably i'm lucky!