Flash Technology
Revision A - 2/13/2020
59
COMPONENT TESTING
Always make resistance measurements with the primary power turned off. However, you must make voltage
measurements with power applied. Thus, for your safety, carry out all preliminary steps such as connecting test
leads or circuit jumpers or disconnecting existing circuit connections with the power off.
TROUBLESHOOTING
The most effective troubleshooting procedure begins with observing the behavior of the system. This often leads
directly to a faulty component or other abnormal condition.
A2D VALUES (ANALOG TO DIGITAL)
The following information will provide details on how to use the Vanguard LED system diagnostic (A2D/Analog to
Digital) values to diagnose failures within the LED flashhead (FH 270).
An LED string has two measurements for operation. String current and string voltage.
Description
Meaning
String Current (C)
Level of Light Intensity
String Voltage (V)
Health of the LED Strings
The string voltage indicates open or shorted LEDs in a string.
As LEDs fail in a shorted state, the string voltage will drop at an equal rate depending on the operating mode.
The FH 270 has 390 LEDs across three panels.
Flashhead (FH) Type
LED String Quantity (per panel)
FH 270
5 White strings with 24 LEDs per string
5 Red LEDs
5 Infrared LEDs
NOTE! The Red and IR strings are distributed across all three panels as one string (1/3 string per panel).
Failure
Result
LED string fails in an open state
Very high string voltage and minimal string current
LED fails in a shorted state
When a single white LED fails in a shorted state, the string
voltage will drop by 1/24
th
or 4.1%
When single red or IR LEDs fails in a shorted state, the string
voltage will drop by 1/15
th
or 6.7%
String current will remain the same.
