Without the board connected to the TV the supplies may not read correctly anyway, but the most common issues are high-ESR electrolytic capacitors, such as the reservoir capacitors on the output rails. You can check them unpowered in-circuit with an ESR meter, or with the board powered up using an oscilloscope on the capacitors, if they are high ESR you will get high ripple on them.
So are your readings with the board connected to the TV, or have you connected the board to dummy loads as specified in the list above?.
For that matter, is there any reason you suspect the PSU board is at fault?.