POWER SUPPLY ISOLATION PROCEDURE
Each regulated supply has numerous feed points to ex
ternal loads throughout the instrument. The power distribu
tion diagram is used in conjunction with the schematic
diagrams to determine those loads that can be isolated by
removing service jumpers and those that cannot.
The power distribution and circuit board interconnections
diagrams are divided into circuit boards. Each power supply
feed to a circuit board is indicated by the schematic diagram
number on which the voltage appears. The schematic dia
gram grid location of a service jumper or component is given
adjacent to the component number on the power distribu
tion and circuit board interconnect diagrams.
If a power supply comes up after lifting one of the main
jumpers from the power supply to isolate that supply, it is
very probable that a short exists in the circuitry on that sup
ply line. By lifting jumpers farther down the line, the circuit in
which a short exists may be located.
Always set the POWER switch to OFF before soldering
or unsoldering service jumpers or other components and
before attempting to measure component resistance values.
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