Service manual

PN 4237242C
2.2-2
INSTRUMENT DESCRIPTION
POWER SUPPLY
Switches
r Power On/Off switch - used as instrument’s Power ON/OFF switch
r Ac Select switch - selects 115 or 230 Vac supply (not accessible when in unit)
AC Power/Vacuum Relay Card
The AC Power/Vacuum Relay card is found in the lower chassis (Figure 2.2-2) and takes the
ac input and distributes it. The card receives ac directly from line input and directs it for
system use. Ac into the card is first sent through relay K2. This relay directs ac to the voltage
selector plug when it is energized by +12 V, input from the AT power supply in the upper
chassis. The ac is then directed to transformer T1 for use by the Linear Power Supply card, to
the +24 V power supply, and to solid state relay K1. The ac hot (black) line to relay K1 is sent
through fuse F1, a 0.4-A, 250-V SLO-BLO fuse. A VAC ON signal of +24 V energizes K1,
which provides ac to the vacuum pump, (shown on Figure 2.2-2), turning it on.
The input and output connectors and test points are shown on Figure 2.2-3 and the line input
ranges are summarized on Table 2.2-2, at the end of this section.
C