Installation Instructions
D. Read the entire Installation Instructions and resolve any issues you may have before starting
the installation. This may eliminate any delays once the installation is started.
E. Check that the instrument make and model marked on the side of the instrument and on the
invoice are correct before starting the installation. The S-50 Shunt is marked "100MV" and
"100 AMP". The S-300 Shunt is marked "50MV" and "300 AMP."
F. Before starting the installation make sure the unit will fit in the location you intend to install it
without obstructing the operation of any controls.
G. If this instrument is to replace an existing unit in the aircraft, it is the installer's responsibility
to move or replace any existing instruments or components in accordance with FAA approved
methods and procedures.
2. Instrument Set Up
On the back of the VA-1A is a hole allowing access to a small switch. The switch furthest to the
right in this window sets the VA-1A for a 12 or 24 volt system. The other switches have no affect
on the operation of the VA-1A. If you have a 12-volt system set this switch down. If you have a
24-volt system set this switch up.
Switch Access Hole
Switch Up = 24V.
Switch Down = 12V
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VA-1A
Back Panel
Internal Shunt (VA-1A
only)
3. Determine how the VA Unit will be installed in your aircraft’s electrical system
Obtain an electrical diagram of your aircraft’s alternator/starter system from the service manual.
There are two common ways an ammeter is installed in an aircraft. One method is with the amme-
ter in the generator or alternator lead. The other method is with the ammeter in the battery lead.
The VA-1A or VA-1A-XX may be installed using either method. The advantages and disadvan-
tages of each method are listed below.
1. Important Information and Initial Check Out
Installation Method
Advantages
Disadvantages
Battery Lead:
1. Shows load current on the
ground (engine off) and durring
an alternator failure.
2. All Warning Lights are
operational.
1. Cannot show load current durring
flight or when the engine is running.
Alternator Lead:
1. Shows load current durring
flight or when the engine is
running.
2. All Warning Lights are
operational.
1. Cannot show load current when
the engine is off or durring
analternator failure.
