HYDRA
Service Manual
5-24
REVIEW
REM SCAN
x1 k
EXT
SET FUNC
mV
TR
1
Ω
s41f.eps
Figure 5-10. Display Test Pattern #1
LAST
MAX
MIN
AUTO MON
M
LIMIT HI
LO
OFF
CAL
PRN
Mx+B ALARM
°
C
°
F RO
AC DC
Hz
CH
2
F
s42f.eps
Figure 5-11. Display Test Pattern #2
When a Hydra display is initially powered up, all display segments should come on
automatically. If this display does not appear, proceed with the following steps:
Note
If the display is operational but has problems whenfront-panel buttons are
pressed, proceed directlyto step 9.
1.
Check the three power supplies with respect to GND (A2TP3 or A2U1-42) on the
Display Assembly.
•
VCC (A2U1-21) 4.85 to 5.35V dc
•
VEE (A2U1-4)-4.75 to -5.25V dc
•
VLOAD (A2U1-5)-28.5 to -32.0V dc
2.
Check the filament drive signals FIL1 and FIL2; these connect to the last two pins
on each end of A2DS1. These signals should be 5.4V ac with FIL2 biased to be
about 6.8V dc higher than the VLOAD supply (nominally a -23.2V dc level). FIL1
and FIL2 should be 180 degrees out of phase. If the dc bias of FIL2 is not at about -
23.2V dc, the display segments that should be "off" will show a shadowing (or
speckling) effect.
Note
It may be necessary to disable the watchdog resetby jumpering A2TP1
(A2U5-3, A2U5-11) to GND (A2TP3) toverify the following items.
3.
Check the clock signal CLK1 at A2TP2, A2U1-2, and A2U4-3. This signal should
be a 614.4-kHz square wave (1.628 ms per cycle). This signal depends on an E clock
signal of 1.2288 MHz from the Hydra Main Assembly. If the E clock is 819.2 kHz
(1.221 ms per cycle), it is possible that SWR2 (A2J1-16) is shorted to ground,
causing the Microprocessor to HALT at power-up.
4.
Check the state of the RESET signal (A2U1-1). This signal should be low once the
reset time is completed (after power-up). Also verify that the RESET* signal
(A2U6-3) is high after the reset time is completed.
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...
