HYDRA
Service Manual
5-20
Figure 5-7 shows the timing relationships of the 6303Y Microprocessor lines LIR* and
WR* to the system clock (E) and the address lines A0..A15. The ROM and NVRAM
Chip Enables correspond to the active (low) region shown for the address lines.
If the instrument powers up without any errors, but does not recognize front-panel button
presses or computer interface commands, the problem may be in the Counter/Timer
(A1U2). Normally, this component generates a regular 50-millisecond interrupt at the
IRQ* output (A1U2-9). If this output is low (and never goes high), the Microprocessor
(A1U4) is failing to recognize the interrupt or the microprocessor interface to A1U2 is
not working correctly. Also check output A1U2-6 for a 10-Hz square wave. If this output
is not correct, check for the E clock at A1U2-17, and verify the microprocessor interface
signals (CNTR*, D0 .. D7, A0 .. A2, R/W*, and RESET*.)
E
2.4V
AD
t
0.8V
PW
PW
PW
t
cyc
EL
EH
t
t
t
t
t
t
t
t
t
t
t
t
t
Ef
AH1
2.4V
0.8V
AH2
HRW
RW
2.4V
0.8V
t
RWD
DDW
HW2
HW1
2.4V
0.8V
DSR
ACC
HR
HLR
DLR
2.0V
0.8V
0.8V
A
0~
R/W
RD,WR
MCU Read
MCU Write
D
0 ~
D
7
D
0 ~
D
7
LIR
A
15
,
Er
s38f.eps
Figure 5-7. Microprocessor Timing
Summary of Contents for 2620A
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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...
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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...
