Cirris Signature 1000R+, User Manual

Page: 48 / 88

Section 10: Select a Test Procedure / Limitations when testing complex assemblies
1000R+ User’s Guide / page 49
Limitations when
testing complex
assemblies
When you test complex assemblies, remember these things:
1. Any connections which have resistances between the Wire Resistance and the
Component Resistance are seen by the analyzer as errors. The resistances are too
low to be seen as components, and too high to be seen as wires.
2. The connection pattern for test points which have resistances below the Wire
Resistance must match the wire connections specified in the cable’s documenta-
tion.
3. All points in a cable assembly that are not connected by either components or
wires must be insulated from each other by resistances which are greater than the
Insulation Resistance setting.
4. All connections which have resistances that fall between the Component Resis-
tance setting and the Insulation Resistance setting are seen by the analyzer as
components. They must have a corresponding Component Check, and must pass
the test for that check.
Testing cables
terminated at only one
end
You may run into situations where you have a cable that is terminated with a connec-
tor at only one end, but where the wires on the other end are left loose. Because you
cannot plug loose wires into your analyzer, these cables pose some problems. There
are three solutions to choose from:
1. Double the cable’s length and terminate both ends. If the cable is wired one-
to-one (such as a flat ribbon cable), you might make the cable twice as long as it
needs to be. You can then place connectors on both ends, and test the cable as a
complete cable. If the cable tests as good, simply cut it in half and you’ll have
two good cable assemblies terminated at only one end.
2. Do two-step testing for shorts and opens.
• First, check for shorts by connecting the terminated end of the cable to
your 1000R+. When you turn it on, the analyzer should not learn any
connections. If it does learn connections, the cable has shorts. If your
cable has loops in it (connections that go from one pin on the terminated
connector to another pin on the same terminated connector), the ana-
lyzer should always learn these loops when you use this approach. To
test for shorts, you will have to document these loops and make sure the
correct signature is displayed by the analyzer.
• Then, check the cable for opens by connecting the terminated end of the
cable to the analyzer, then shorting all the loose wire ends together.
Document this so you know what the correct signature should be. All
wires should appear to be shorted together. If an open exists, the open
pin will not appear to be shorted to all the other pins, and the signature
will change.
3. Put the analyzer in test mode, then check loose ends using the hand-held test
probe. Use the probe for testing a cable with colored wires when you need to
make sure that colored wires correspond to specific pins. Since the probe works
only when the analyzer is in test mode, you’ll need to short two of the loose wires
together, or use the probe to create a connection that the analyzer can learn. Then
remove the connection. This will put the analyzer in test mode. Now, when you