
HP5501B
Service
8-26
8-73. A1 CONNECTOR BOARD CIRCUIT THEORY
8-74. The A1 Connector Board interconnects the main laser cable, laser tube heater and power amp,
laser power supply, and the A3 Controller/Reference Board. The schematic diagram for A1 is
shown in Figure 8-23. Additional information covering heater power amp control circuitry can be
found in paragraph 8-119.
8-75. Capacitors A1C1 through A1C4 serve to filter out noise on the ±15 Volt power supply lines.
Capacitors A1C6 and A1C7 and inductors A1L1 and A1L2 filter current spikes created by the
high voltage power supply and the switching power amplifier. Diodes A1CR1 and A1CR2 provide
reverse voltage protection. Switch A1S1 is a safety interlock which removes power from the laser
high voltage power supply when the
HP5501B
covers are removed. Switch A1S2 bypasses the
interlock so that the laser can be serviced. A1S1 and A1S2 are wired in such a way that the
interlock must be enabled before replacing the covers. A1F1 and A1F2 protect the system
against laser power supply failures. A1J4 is the connector for the laser tube heater and cathode.
A1DS3 and A1DS4, +15V POWER ON and -15V POWER ON LED’s respectively, turn on when
the power cable is connected to POWER connector A1J5. A1DS7 (LASER ON LED) lights when
the high voltage supply is powered on, and A1DS8 (READY LED) lights when the
HP5501B
is
ready for use. A1R12 is used to adjust laser current as per the adjustment procedures in
Section
5.
8-76. High Voltage Power Supply Switch (A1Q3 and A1Q4)
8-77. When optical mode begins, the laser beam should be on. This is accomplished by applying the -
WARMUP logic line through current limiting resistor A1R10 to the base of transistor A1Q4. A1Q4
saturates which, in turn causes A1Q3 to turn on and saturate. The high voltage power supply
senses ground through saturated A1Q3, thus turns on.
8-78. If
the
HP5501B
left and right covers are placed on the unit prior to resetting the TEST-NORM
switch (A1S2) to NORM; both SUPPLY UNBALANCE LED’s will turn on. When power is applied,
A1 transistors Q1 and Q2 sample the heater switching voltage through ac voltage divider A1R23
and A1R24. A1C5 ensures that transistor bases of A1Q2 and A1Q2 remain at "virtual" dc ground
so that the unbalance circuits operate normally.
8-79. Power
Distribution
8-80. When +15 Vdc and -15 Vdc are applied to the laser head, the ±15V POWER ON light-emitting
diode indicator (on the A1 Connector Board) are forward biased and illuminate. The dc input
potentials also produce a virtual ground level at the junction of two 14.7K Ohm resistors. This
balanced condition results in an open circuit at transistors A1Q1 and A1Q2. An unbalanced
condition exists when either the positive or negative dc input deviates from 15 Volts by
approximately 1 Volt or more. This offset causes a corresponding forward biasing of A1Q1 or
A1Q2 thus placing the anode of LED DS5 or DS6 (±15V SUPPLY UNBALANCE) at "virtual"
ground potential. Table 8-2 lists the unbalanced DC voltage conditions and the resulting
unbalanced indications.
Table 8-2. DC Unbalanced Failures
UNBALANCED INDICATORS
DC INPUT VOLTAGE UNBALANCED CONDITION
+15V SUPPLY
UNBALANCE
-15V SUPPLY
UNBALANCE
+15 Vdc
High (more positive)
ON
OFF
Low (less positive)
OFF
ON
-15 Vdc
High (more negative)
OFF
ON
Low (less negative)
ON
OFF
Содержание 5501B
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Страница 5: ...iii LASER HEAD SAFETY LABELS ...
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Страница 13: ...HP5501B Installation 1 1 Figure 1 1 HP5501B Laser Head ...
Страница 21: ...HP5501B Installation 2 3 10778B LENGTH 10 METRES 32 8 FT Figure 2 1 HP 10778B Power Cable ...
Страница 22: ...HP5501B Installation 2 4 10779B LENGTH 10 METRES 32 8 FT Figure 2 2 HP 10779B Reference Cable ...
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Страница 57: ...HP5501B Replaceable Parts 6 11 6 14 Exploded View Figure 6 1 HP5501B Laser Head Exploded View ...
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Страница 62: ...HP5501B Service 8 2 Figure 8 1 Schematic Diagram Notes ...
Страница 66: ...HP5501B Service 8 6 Figure 8 2 HP5501B Laser Head Block Diagram ...
Страница 91: ...HP5501B Service 8 31 Figure 8 18 High Voltage Power Supply Schematic Diagram ...
Страница 110: ...HP5501B Service 8 50 COMPONENT SIDE CIRCUIT SIDE SERIES 2632 REV A Figure 8 23 A1 Connector Board Component Locator ...
Страница 111: ...HP5501B Service 8 51 Figure 8 23 A1 Connector Board Component Schematic Diagram ...
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