Great Manual. It was exactly what I was looking for
Text excerpt from page 48 (click to view)
Power Supply CBA Bottom View
NOTE: The voltage for parts in hot circuit is measured using hot GND as a common terminal.
Because a hot chassis ground is present in the power supply circuit, an isolation transformer must be used. Also, in order to have the ability to increase the input slowly,when troubleshooting this type power supply circuit, a variable isolation transformer is required.
