Main Power Supply - Keithley 595 Instruction Manual

THEORY OF OPERATION
7.12 MAIN POWER SUPPLY
The diagram for the main power power supply is locatkd
on drawing 595-106, page 1. AC power is applied to JlOl3,
which is the power ctinnetior located on the rear panel of
the inshument: SlOl is the POWER switch located on the
front panel, while 5102 is the liie voltage selection switch.
When 5102 is in the ll5V positiok, the primary windings
are connected in parallel; when S102 in in the 230V posi-
tion, the 'llO2 windigs are placed in series.
1102 has three secondary wirdings which are used to supp-
ly the i24V, kl5V and +5V supplies. The %24V and iJ5V
sources supply the voltage source analog outputs,
preamplifier, and the +5V supplyis used for the digital
chlitly.
The +24V supplies consist of half-wave rectifier diodes
(CR108 and CRlU7) and filter capacitors (CllO and Clll).
Each of the kl5V supplies has a similar half-wave rectifica-
tion scheme (CR101 and Cl03 for the -l5V supply, CR109
and Cl08 for the cl5V supply). Regulation for these sup-
plies is performed by UN4 and U143, which are IC
regulators.
The third winding of 7X02 supplies the +5V (c5D) source
that is used to power the digital circuits. Rectification is
done by elements of CRllO, while filtering is performed by
ClOl. The supply voltage is regulated by Ul!X, which is a
standard 7805 IC regulator.
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