Keithley 486 Instruction Manual page 157

SECl7ON 6
7Reoy
of
Operation
lines (DIOI-DIO8), and U515 supports management and
handshake lines.
6.6 POWER SUPPLIES
Figure 6-17 shows a block diagram of the power supply
section. The power supply schematic is located on draw-
ing486-106 (page 3) for the Mode1486 01487-106 (page 3)
for the Model 487.
To Digital To Digital
Board Board
To Analog To Analog
)
I+-++ To
Analog
Figure 6-17. Power Supply Block Diagram
6.6.1 AC Line Input
The AC power line voltage is applied through JlCKX to
the power transformer, TlOO. SlOl is the on/off switch,
and FIOO is the line fuse that provides protection to the
line voltage input circuits. SlOO switches between
9C-125V and 180~250V AC operation.
6.6.2 +-15V Supplies
Theil5V power supplies provide power to all the ampli-
fier stages on the analog board. Rectification for the+l5V
supplies is performed by CRIOS, while Cl14 and Cl08
provide filtering. U106 regulates the +15V supply, and
U108 regulate the -15V supply. Output filtering is per-
formed by Cl22 and C1'23.
6.6.3 +%A Supply
The +5VA supply powers the analog control circuits and
relays located on the analog board. CR106 rectifies in-
coming AC, and Cl17 filters the ractifier output. U107
regulates the supply to its nominal +5V value, and Cl21
provides output filtering.
6.6.4 +6.5V Supply
The +6.5V supply powers circuits on the digital board.
CR109 redifks the 8V AC input voltage, while Cl15 fil-
ters the output. The output of the +6.5V supply is further
regulated to +5V by a separate power regulator located
on the digital board WOO). This +5V supply also sup-
plies the display board.
6-14