Avtron Model T477W Bonding Meter
with B14703 Battery Pack Replacement Instructions
Part Number T477WC15292
Operating Instructions
Subject to the EAR, ECCN [9E610.a].
This information is subject to the export control laws of the United States, specifically including the Export Administration Regulations (EAR),
15 C.F.R. Part 730 et. seq. Transfer, retransfer, or disclosure of this data by any means to a non-U.S. person (individual or company), whether in the United States or abroad, without any
required export license or other approval from the U.S. Government is prohibited, including without limitation any diversion to a military end user or use in a military end use application.
2-4
2.7
C15478 and C15480 Probe Sets (Optional)
These probe sets (Figure 2-2) do not have separate current and voltage leads. Their use may cause meter reading error
exceeding the allowed tolerance due to the coupling effect. They should only be used for survey work to establish an
approximate resistance.
Meter reading error caused by the use of probe sets C15478 and C15480 depends on the probe lead configuration. In order to
identify the magnitude of error, tests have been conducted using a wooden surface to simulate air and an aluminum sheet to
simulate an aircraft structure. Meter error on wooden surfaces was on the order of 20 digits. Error measured on the aluminum
surface ranged from 20 to 240 digits, depending on the size of the cable loop formed. When using the C15478 and C15480,
form the smallest possible cable loop diameter (see Figure 2-1).
NOTE
The current and voltage leads are identified by the following GRIP COLOR CODE:
Black is for positive and negative current.
Red is for positive and negative voltage.
(Additionally, on the compass style probes, the blunt spring-loaded tip is voltage, while the pins
are current.)
On the C15478 and C15480 probe sets sold after November 1989, Avtron Aerospace, Inc. has
enhanced their design by adding sleeving to the first 40 inches of the cables. This helps to
minimize the meter reading error induced by the coupling effect.
The polarity signs imprinted on the clamps of these probes have no meaning.
2.8
C16695 Probe Set (Optional)
These probes (Figure 2-2) have separate current and voltage leads, and the voltage sensing leads are bound together for nearly
the full length of the cable, which best minimizes the coupling effect. The best-rated meter accuracy is obtained with this
probe set when connected such that the meter reading is
positive
only. This probe set may be used for calibrating the T477W
Bonding Meter and whenever measurement accuracy is crucial. Since all the probes are of the pencil type, they are well suited
for taking accurate measurements on small parts or in cramped space locations.
NOTE
The black pencil style probes are positive and negative current while the red pencil style probes
are positive and negative voltage. Make sure to observe polarity while making a measurement
such that the voltage and current probes on each side of the bond are of the same
lead
color.
2.9
Custom Probe Sets
T477W probe sets are constructed with extensive use of non-sparking materials such as aluminum, brass, and copper. This
design minimizes the possibility of spark ignition if the probes are dropped and happen to strike a surface. The fabrication of
custom-made probes is not recommended.
