268XA
Service Manual
2-10
The overvoltage protection for these 3 signals consists of a 49.9
Ω
series resistor, a dual
diode clamp and a 6 V Zener diode. This scheme will protect the fpga and
microprocessor for applied voltages up to +/- 30 V dc. The trigger input buffer is a
CMOS Schmidt trigger. The trigger out and master alarm out are driven by NDS351
NMOS FETs with 2 k
Ω
pull-up resistors to the +5 V rail.
PCMCIA Interface PCA (2686A-4041)
The PCMCIA interface board mainly consists of a type II 3.3 V PCMCIA v2.1 card slot
and a set of bi-directional levelshifting buffers. The buffers on this board are driven off of
the same supply as the card, which can be either 3.3 V or 5 V. The buffers on 4004 board
are always powered from Vcc (3.3 V), as the MPC855T can not tolerate 5 V signal
levels. This board also has a 5 V to 12 V boost topology switching regulator that is only
turned on if the installed card says that it needs 12 V for programming. This 12 V supply
was designed to only provide enough power for the PCMCIA card, no other devices
should be powered from this supply. This board plugs into P4 on the 2680A-4004 PCA.
It is a daughter card that is only installed if the instrument is a 2686 chassis, as opposed
to a 2680 chassis which has no PCMCIA option.
Backplane PCA (268XA-4001)
The backplane PCA is the board that the 6 modules and the display controller PCA
physically plug into. It contains minimal circuitry, only that which is needed for signal
integrity and ESD protection. It is basically a pass through board for the guard crossing
signals from the fpga to the modules, and the SPI bus that goes to the display and the
calibration EEPROMs from the MPC855T on the 4004 controller PCA. Refer to the 1001
schematic for reference designators. The backplane PCA contains a number of testpoints
that are usable for service. TPs 3, 4, 8 and 11 are connected to the guard crossing signals
for module slot #1. 3 and 4 are the UART receive and transmit lines from the outguard
fpga. 8 and 11 are the differential guard crossing clocks that drives the in-guard power
supply. TPs 13, 12, 1 and 2 are the same signals for module slot #6, respectively. The
remaining testpoints on the backplane board are connected to the display controller
interface signals. TP15, and 16 are the tri-state buffered SPI clk and transmit signals.
TP17 is the master display clock that comes from a baud rate generator on the MPC855T.
TP18 is the +5 V power rail. TPs 9 and 10 are the VFD ac power source.
Table 2-2. Backplane Connector Description
Connector Reference Designator
Description
P1
20 pin header for module slot #1
P2
20 pin header for module slot #2
P3
20 pin header for module slot #3
P4
20 pin header for module slot #4
P5
20 pin header for module slot #5
P6
20 pin header for module slot #6
P7
100 pin through hole connector to the controller board
P8
20 pin surface mount header for display connection ribbon cable
Summary of Contents for 2680A
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Page 204: ...268XA Service Manual 7 10 268X FINAL ASSEMBLY alg105f eps Figure 7 1 268XA Final Assembly ...
Page 207: ...Replaceable Parts Parts Lists 7 7 13 2680A DIO alg100f eps Figure 7 3 DIO Module ...
Page 209: ...Replaceable Parts Parts Lists 7 7 15 2680A FAI alg102f eps Figure 7 4 FAI Module ...
Page 211: ...Replaceable Parts Parts Lists 7 7 17 2680A PAI alg103f eps Figure 7 5 PAI Module ...
Page 214: ...268XA Service Manual 8 2 ...
Page 215: ...8 3 8 Schematic Diagrams Figure 8 1 Backplane PCA 2680A 4001 ...
Page 216: ...268XA Service Manual 8 4 Figure 8 1 Backplane PCA cont 2680A 1001 ...
Page 217: ...8 5 8 Schematic Diagrams Figure 8 2 Controller System Power PCA 2680A 4004 ...
Page 223: ...8 11 8 Schematic Diagrams Figure 8 3 Digital I O PCA 2680A 4006 ...
Page 224: ...268XA Service Manual 8 12 Figure 8 3 Digital I O PCA cont 2680A 1006 1 of 3 ...
Page 225: ...8 13 8 Schematic Diagrams Figure 8 3 Digital I O PCA cont 2680A 1006 2 of 3 ...
Page 226: ...268XA Service Manual 8 14 Figure 8 3 Digital I O PCA cont 2680A 1006 3 of 3 ...
Page 227: ...8 15 8 Schematic Diagrams Figure 8 4 Backplane Extender PCA 2680A 4009 ...
Page 228: ...268XA Service Manual 8 16 Figure 8 4 Backplane Extender PCA cont 2680A 1009 ...
Page 229: ...8 17 8 Schematic Diagrams Figure 8 5 Extender PCA 2680A 4010 ...
Page 230: ...268XA Service Manual 8 18 Figure 8 5 Extender PCA cont 2680A 3010 ...
Page 231: ...8 19 8 Schematic Diagrams Figure 8 6 A D Supply Assembly 2680A 4031 ...
Page 232: ...268XA Service Manual 8 20 Figure 8 6 A D Supply Assembly cont 2680 1031 ...
Page 233: ...8 21 8 Schematic Diagrams Figure 8 7 PCMCIA PCA 2680A 4041 ...
Page 234: ...268XA Service Manual 8 22 Figure 8 7 PCMCIA PCA cont 2686 1041 ...
Page 235: ...8 23 8 Schematic Diagrams Figure 8 8 Output PCA 2680A 4062 ...
Page 236: ...268XA Service Manual 8 24 Figure 8 8 Output PCA cont 2680A 1062 ...
Page 237: ...8 25 8 Schematic Diagrams Figure 8 9 A D PFE PCA 2640A 4003 ...
Page 238: ...268XA Service Manual 8 26 Figure 8 9 A D PFE PCA cont 1 of 6 ...
Page 239: ...8 27 8 Schematic Diagrams Figure 8 9 A D PFE PCA cont 2 of 6 ...
Page 240: ...268XA Service Manual 8 28 Figure 8 9 A D PFE PCA cont 2640A 1003 3 of 6 ...
Page 241: ...8 29 8 Schematic Diagrams Figure 8 9 A D PFE PCA cont 2640A 1003 4 of 6 ...
Page 242: ...268XA Service Manual 8 30 Figure 8 9 A D PFE PCA cont 2640A 1003 5 of 6 ...
Page 243: ...8 31 8 Schematic Diagrams Figure 8 9 A D PFE PCA cont 2640A 1003 6 of 6 ...
Page 244: ...268XA Service Manual 8 32 Figure 8 10 A D FFE PCA 2645A 4003 ...
Page 245: ...8 33 8 Schematic Diagrams Figure 8 10 A D FFE PCA cont 2645A 1003 1 of 6 ...
Page 246: ...268XA Service Manual 8 34 Figure 8 10 A D FFE PCA cont 2645A 1003 2 of 6 ...
Page 247: ...8 35 8 Schematic Diagrams Figure 8 10 A D FFE PCA cont 2645A 1003 3 of 6 ...
Page 248: ...268XA Service Manual 8 36 Figure 8 10 A D FFE PCA cont 2645A 1003 4 of 6 ...
Page 249: ...8 37 8 Schematic Diagrams Figure 8 10 A D FFE PCA cont 2645A 1003 5 of 6 ...
Page 250: ...268XA Service Manual 8 38 Figure 8 10 A D FFE PCA cont 700p29_topress zip 2645A 1003 6 of 6 ...
Page 251: ...8 39 8 Schematic Diagrams Figure 8 11 Analog Input Connector PCA 2620A 4004A ...
Page 252: ...268XA Service Manual 8 40 2620A 1004 Figure 8 11 Analog Input Connector PCA cont ...
Page 253: ...8 41 8 Schematic Diagrams Figure 8 12 Display PCA 1 of 1 ...
Page 254: ...268XA Service Manual 8 42 Figure 8 12 Display PCA cont 1 of 1 ...