Assembly-Level Service
Theory of Operation
Power Supply Block
Option 048: The first sentence of the first paragraph at the top of page 3-22 is changed:
The Power-Supply Block consists of LF1 line filter/cable assembly, T1 toroidal power transformer, A1 rectifier/crowbar/Ext dc input filter circuits, A11 power steering logic assembly, and A12 Dc-Dc power- converter module.
Option 048: The second paragraph at the top of page 3-22 is changed:
The power-supply block provides the instrument with internal dc power from either an ac power or external dc power source. It monitors the presence of these power sources, switching from external dc to ac line as required.
Option 048: The voltages specified in the third paragraph on page 3-22 are changed:
28 Vrms is 37 Vrms and 32-38 Vdc is 45-51 Vdc
Option 048: The fifth paragraph on page 3-22 is deleted:
Option 048: The sixth paragraph on page 3-22 is changed:
A11 implements the power-source steering hierarchy and provides power-status signals to A3. A11 receives the dc and ac power sources, selects one of them and routes it to the A12 Dc-Dc power converter module.
Option 048: The last paragraph on page, 3-22 is changed:
A12 converts the 40-58 Vdc steered power to nominal +5V, +12V, and -12V dc and routes these three voltages to A1 at A1J2.
