Need help with SMPS output voltage higher than spec

[Edib]

SMPS Schematic

https://www.allen-heath.com/media/xone_db4_db2_004_066_psu_2.pdf

Hello there
I have a music mixer failing components downstream from the PSU.
After some investigation, I realized the voltage output from the PSU is higher than specified on the board or schematic.

Output should be +/-12 however reading 19v or higher. I attached a 10ohm 3w resistor to pins 9 and 3 on CN1 (see schematic) and the 12v rail jumped to 26 v.

What may be going on here?

 

[scopeprobe]

The black connection of the DVM doesn't appear to across the output but instead look to be measuring with respect to chassis. The output needs to be measured with respect to TGND

 

[Edib]

The black connection of the DVM doesn't appear to across the output but instead look to be measuring with respect to chassis. The output needs to be measured with respect to TGND

I remeasured the output to TGND, the DMM reads the same, ~ +/-25V

I loaded connected a 10 ohm 3 watt resistor in parallel to pin 3 and 9, then DMM probed pin 1 and pin 11.

 

[mtwieg]

The schematic shows that the +5V output is the only output regulated by the SMPS. Is the 5V output correct?