All lit up now, voltages are different between channels (or at least either side of the centre pad in the middle of the board.
With black multimeter lead on the centre pad I read -23.3v on one side and +9.98v on the other.
With black multimeter lead on the centre pad I read -23.3v on one side and +9.98v on the other.
You achieved 9.98V positive which was correct but -23.3V negative was just Raw DC with no regulation to about -10V. There are further problems in the build.
Make a thorough inspection that all Mosfets are the proper types where they are located and that the BC550 560 transistors are in the right places also. Orientation checks on all small semis too.
You can replace them with one 10 Ohm chunky resistor for now if you got one handy, in any of their two positions as they are wired in parallel. But not before finding about the other problems because it will eventually burn out too.
Remove all Rset and measure Raw DC between their close to the 4700uF caps pins and ground. That will establish if basic DC figures are right and isolate the shunt regulators from the Raw DC for no further incidents during those measurements. Inspect the Mosfets insulation thoroughly too. No metal tab must show continuity to the chassis.
All capacitors are correctly orientated, bc 550 and 560 are correct, mosfets are insulated from bolts and chassis they're bolted to.
Measure DC from Rset pad nearest to large capacitors once Rset are removed?
Measure DC from Rset pad nearest to large capacitors once Rset are removed?
If it was pin 3 counting from left to right as you face a K170 it wasn't wrong. If it was pin 1 it was wrong.
After removing the Rset resistors I tried the pads closest to the board ends for continuity to ground. The channel that worked first time has continuity, the other, which fried the resistors, doesn't