Double regulated power supply

Hello
The goal is to change an old HP test inst.power.The transformer as one output with a middle tapeNOT wired on Ground.It give about 36vDC.This is regulated by 2N3055 and give Vout of 26v.FloatingThen this 26v are splitted in a +20v 4A ajustable and a -6.3V 1A,measured to ground(ground is catched on a serie -6.3v transistor.
This power is defect,and as it contains numerous TR and Zener I want to use todays regulators as LM317 or 350..How do Idesign this floatind power splitted into these 2 power?Thanks

What is the AC voltage across the power transformer secondary windings from the tap to either other end of the winding?

Are you in a 50Hz or 60Hz country?

Hello
Sorry to reply so late.
I d 36V rectified DC to use and split it into +20v 4A and -6.3V 1A.The rectifier and transf. go OK
It s to replace a power supply of an HP8601A,these is too old(1970) and contains much TR an zener...It goes suddently away,a zener 7.5v 10w between -6.3 and ground burn out.All TR I d replace,nothing goes netter.I d +24V impossible to go down 20v;and -6.3v is -0.8v!
Whithout scheme you cannot understand.You can if it s possible go to bama.com and search HP8601A sweeper,power schme A8
Thank from F for your kind answer