Main Board Power Distribution (Diagram 13); Processor Power Board; Distribution (Diagram 14); Interconnection Diagram (Diagram 15) - Tektronix 2246 1Y Service Manual

Theory of Operation—2246 1Y and 2246 Mod A Service
the Inverter power transformer consist of rectifier
and filter components only. All the regulation is done
by the Preregulator and Inverter Control circuitry in
the primary side of the transformer. Both half-wave
and full-wave rectifiers are used, and either simple
capacitor or capacitive-input PI filter circuits are
used. Rectifier and filter type used for each of the
secondary voltages depends on the load require­
ment. A single 130 Vac output from pin 12 of T2204
supplies the drive to the Z-Axis dc restorer circuitry.
Power for the blower fan is supplied by the -15 V
power supply line.
The center-tapped secondary winding from pins 13 to
15 of T2204 is used for the +5 V and -5 V supplies.
Both are full-wave rectified and filtered using capaci­
tive-input Pi filters.
High-Voltage Supply
The high-voltage power supply uses two secondary
windings of T2204: one for high-voltage multiplier
U2230 and the other for the crt filament. Flying leads
from the top of the transformer make the circuit con­
nections into the high-voltage circuitry. The crt fila­
ment winding consists of a few turns of insulated wire.
The high-voltage winding attaches directly to the HV
Multiplier. Outputs from HV Multiplier U2230 are the
13.3 kV to the crt anode via a high-voltage-insulated
connecting lead and the -2 .7 kV.supplied to the crt
cathode, focus grid, and intensity grid. The -2 .7 kV
supply is filtered by a two-section capacitive input RC
3-58
filter. A neon lamp across the second section of the
filter provides protection against arcing if there is a
failure that can cause a large difference of potential
to develop between the crt heater and cathode cir­
cuits.
MAIN BOARD POWER DISTRIBUTION
(Diagram 13)
The Main Board Power Distribution diagram schemati­
cally displays the distribution paths and decoupling
circuits for the low voltages from the Power Supply.
The supply and ground connections to the various in­
tegrated circuits in the instrument are also shown.
Use this diagram to aid circuit tracing when trying to
locate a power supply loading problem associated
with the Main Board.
PROCESSOR BOARD POWER

DISTRIBUTION (Diagram 14)

The continuing power distribution from the Main Board
to the top board (Processor Board, A16) is depicted
in the Processor Board Power Distribution schematic
diagram. Use Diagram 14 to aid in locating power
supply loading problems that are isolated to the Proc­
essor Board.
INTERCONNECTION DIAGRAM
(Diagram 15)
Circuit board interconnections with the plug, jack, pin
numbers, and signal names shown are found in sche­
matic Diagram 15. The diagram is useful in checking
continuity of cable runs and signal paths from board
to board through the instrument.
REV OCT 1991