Diagnostic Testing and Troubleshooting
Introduction
6
6-3
Introduction
The 268XA device provides error code information and semi-modular design to aid in
troubleshooting. This section explains the error codes and describes procedures needed to
isolate a problem to a specific functional area. Finally, troubleshooting hints for each
functional area are presented.
First, if the device fails, check the line voltage fuse and replace as needed. If the failure is
associated with the dc power, you will need to open the top cover to check the internal dc
power fuse. See Chapter 3, Maintenance, for details. If the problem persists, verify that
you are operating the device correctly by reviewing the operating instructions in the
268XA Users Manual.
XW
Warning
Opening the case may expose hazardous voltages. Always
disconnect the power cord and measuring inputs before
opening the case. In addition, remember that repairs or
servicing should be performed only by qualified personnel.
Signal names followed by a ’*’ are active (asserted) low. Signal names not so marked are
active high.
Servicing Surface-Mount Assemblies
The device incorporates Surface-Mount Technology (SMT) for printed circuit assemblies
(PCA’s). Surface-mount components are much smaller than their predecessors with leads
soldered directly to the surface of a circuit board. No plated through-holes are used.
Unique servicing, troubleshooting, and repair techniques are required to support this
technology. The information offered in the following paragraphs serves only as an
introduction to SMT. It is not recommended that repair be attempted based only on the
information presented here.
Since sockets are seldom used with SMT, "shotgun" troubleshooting cannot be used; a
fault should be isolated to the component level before a part is replaced. Surface-mount
assemblies are probed from the component side. The probes should make contact only
with the pads in front of the component leads. With the close spacing involved, ordinary
test probes can easily short two adjacent pins on an SMT IC.
This Service Manual is a vital source for component locations and values. With limited
space on the circuit board, chip component locations are seldom labeled. Figures included
in Chapter 8 of this manual provide this information. Also, remember that chip
components are not individually labeled; keep any new or removed component in a
labeled package.
Surface-mount components are removed and replaced by reflowing all the solder
connections at the same time. Special considerations are required.
•
The solder tool uses regulated hot air to melt the solder; there is no direct contact
between the tool and the component.
•
Surface-mount assemblies require rework with wire solder rather than with solder
paste. A 0.02Y-inch diameter wire solder composed of 63% tin and 37% lead is
recommended. A 60/40 solder is also acceptable.
•
A good connection with SMT requires only enough solder to make a positive metallic
contact. Too much solder causes bridging, while too little solder can cause weak or
open solder joints. With SMT, the anchoring effect of the through-holes is missing;
solder provides the only means of mechanical fastening. Therefore, the PCA must be
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 ...