HYDRA
Service Manual
2-22
PASSIVE
FILTER
A/D
HIGH
LOW
A3R34
A3Z4
10.01k
A3K16
S9
S3
S10
A3Z4
10M
A3R10
A3R11
A3K17
S2
INPUT HI
INPUT LO
s4f.eps
Figure 2-4. DC Volts 300V Range Simplified Schematic
When an input is switched in for a measurement, the ohms source in Analog Processor
A3U8 is set to the correct voltage for the range selected and is connected to the
appropriate reference resistor in network A3Z4. A measurement current then flows
through A3Z4, relay A3K16, thermistor A3RT1, resistor A3R10, the unknown
resistance, A3R43, ground, and the ohms source.
The resulting voltage across the unknown resistance is integrated for a fixed period of
time by the A/D Converter through the HI SENSE path of A3R11, A3K17, A3R42 and
A3U8 switch S2, and the LO SENSE path of A3R35 and Analog Processor switch S19.
Passive filtering is provided by A3C34, A3C27, and portions or all of the DC Filter
block.
The voltage across the reference resistor for the 300
Ω
and RTD, 3-k
Ω
, and 30-k
Ω
ranges (the 1-k
Ω
, 10.01-k
Ω
, and 100.5-k
Ω
resistances in A3Z4, respectively) is
integrated for a variable period of time until the voltage across the integrate capacitor
reaches zero. For the 300
Ω
and RTD range, the reference resistor voltage is switched in
through Analog Processor switch S6 and applied to the A/D Converter by switch S8. For
the 3-k
Ω
range, switches S9 and S11 perform these functions, respectively. For the 30-
k
Ω
range, switches S13 and S14 are used. For all ranges, the voltage is routed through
A3R34 to the RRS input.
Summary of Contents for 2620A
Page 4: ......
Page 18: ...HYDRA Service Manual 1 2...
Page 48: ...HYDRA Service Manual 1 32...
Page 140: ...HYDRA Service Manual 3 16...
Page 234: ...HYDRA Service Manual 5A 34...
Page 236: ...HYDRA Service Manual 6 2...
Page 254: ...HYDRA Service Manual 6 20 2620A 1601 s63f eps Figure 6 3 2620A 2625A A1 Main PCA...
Page 258: ...HYDRA Service Manual 6 24 2635A 1601 s64f eps Figure 6 4 2635A A1 Main PCA...
Page 260: ...HYDRA Service Manual 6 26 2620A 4002 CKT 1 CKT 2 s65f eps Figure 6 5 A2 Display PCA...
Page 272: ...HYDRA Service Manual 6 38...
Page 274: ...HYDRA Service Manual 7 2...
Page 282: ...HYDRA Service Manual 7 10...
Page 284: ...HYDRA Service Manual 8 2...
Page 285: ...Schematic Diagrams 8 8 3 Figure 8 1 A1 Main PCA 2620A 2625A 2620A 1601 s88f eps...
Page 288: ...Schematic Diagrams 8 8 6 Figure 8 1 A1 Main PCA 2620A 2625A cont 2620A 1001 3 of 4 s73f eps...
Page 292: ...Schematic Diagrams 8 8 10 2635A 1001 2 of 5 Figure 8 2 A1 Main PCA 2635A cont s76f eps...
Page 293: ...Schematic Diagrams 8 8 11 2635A 1001 3 of 5 Figure 8 2 A1 Main PCA 2635A cont s77f eps...
Page 296: ...Schematic Diagrams 8 8 14 2620A 4002 CKT 1 CKT 2 Figure 8 3 A2 Display PCA s90f eps...
Page 300: ...Schematic Diagrams 8 8 18 2620A 1003 2 of 3 Figure 8 4 A3 A D Converter PCA cont s82c eps...
Page 301: ...Schematic Diagrams 8 8 19 2620A 1003 3 of 3 Figure 8 4 A3 A D Converter PCA cont s83c eps...
Page 302: ...Schematic Diagrams 8 8 20 2620A 1604 Figure 8 5 A4 Analog Input PCA s92f eps...
Page 304: ...Schematic Diagrams 8 8 22 2620A 1605 Figure 8 6 A5 IEEE 488 Interface PCA 2620A Only s93f eps...
Page 306: ...Schematic Diagrams 8 8 24 2625A 1606 Figure 8 7 A6 Memory PCA 2625A s94f eps...
Page 310: ...Schematic Diagrams 8 8 28...
