6 Disassembly and Repair
118 Keysight 33210A Service Guide
Power Supply
Verify the main power supply.
The main power supply provides a +12 Vdc supply to the main circuit board. All
other supplies are derived from this supply. This supply is energized at all times
while the line power cord is connected.
– Circuit failure can cause heavy supply loads which may pull down the supply
output voltage. Disconnect the main supply from the A1 circuit board to test.
– Always check the supply is free of oscillations using an oscilloscope.
– The main power supply provides an input fuse (type UL/IEC127, rated 250VAC
H 3.15A) to protect against the danger of fire in the event of a failure of the
power supply circuitry. However, this fuse will not fail ("open" or "blow") in
normal power supply operation. The fuse fails only in the event of a significant
overload indicating a failure of the power supply circuitry. Replace the entire
main power supply assembly if the input fuse fails. Note that a power supply
failure may be caused by a failure elsewhere in the instrument.
Shock Hazard. To check the power supplies, remove the instrument cover as
described in “Mechanical Disassembly” on page 122.
Power Supply Minimum Maximum
+12 V 11.4 V 12.6 V