Dear john
Regarding the 12v dc that i used is comming from the main huge power supply and its current output is more than what the new amp board need and i did try it for long time on the original 110w×2 8ohm speakers with no over heat on the new board same aswell with old amp althought the new board is very compact and not power monger it can run on 12v- 24v in general as iam not an electronic engineer just a hobbies it was a challenge for me to bring life again to this vintage machine .
Actualy this machine is made from 2 sets one for the amp and casset and radio and another set for the 50+1 cd player conneted to the main set by a ribbone cable and power cord and back again to the bad design both sets has a voltage selector 110-240v last time ayears ago the kids try to use it they change the voltage selector to 240v on main set and didnt notice that the cd set need to be changed at same the result was the cd power suply blown because there is no fuse there it was another challange to be fixed coase there is no info about that output voltage and there is no schematic diagrams for that set to know the output voltage of that power supply after hard time of searching for a replacement i couldn't find any then i decided to desolder the transformer from the board to try winding it i find there at the input section unusable pin not connected to any traces on the board i check out if its connected to other pins and there was there i felt tgere is a hope i connected it serial with 70watt 110v lamp to avoid further damage and the result is the deck works again on 110v then i disconnect the volt selector leaving it direct and i add a small stepdown volt transformer from 240to 110v (i used small 30watt traveller converter which fit inside the deck housing ) it was a real challange but thanx GOD i did it and i liked to share this experience with other people who face this prob with PIONEER products and they like to keep them functioning after many years.