119
FORM 160.54-M1
ISSUE DATE: 10/25/2019
JOHNSON CONTROLS
JCI COMPANY CONFIDENTIAL
9
SECTION 9 - DISPLAY BACKLIGHT INVERTER BOARD
The Display Backlight Inverter Board generates a high
voltage AC signal that is applied to the backlight lamp,
causing it to illuminate. The magnitude of the signal
determines the lamp brightness. Displays by some
manufacturers have two lamps; one at the top and one
at the bottom of the display. Other Display manufactur-
ers have only a lamp at the top of the display.
An Inverter converts low level DC voltage (+12 VDC
or +5 VDC, as required by the manufacturer) from the
microboard to a 500 to 1500 VAC 60KHz signal that
is applied to the lamp. The higher the AC voltage, the
greater the brightness of the lamp. When this voltage is
not present, the lamp is turned OFF.
High voltage, up to 1500 VAC, is present
at the output of the backlight inverter
board. See Figure 48 on page 120 and
Figure 49 on page 121 and locate the
output connectors. Use extreme caution
when working in this area!
Different Display manufacturers require different
Backlight Inverter Boards. The different board designs
require different control voltage inputs. To accommo-
date these variations, Microboard Program Jumpers
JP3 through JP5, JP7 and JP8 must be configured to
provide the required voltage levels. A label attached to
the display mounting plate lists the required Program
Jumper configuration for that particular display. Refer
to required Program Jumper configurations for the var-
ious Display applications.
Under Program control, the microboard generates the
control signals that are applied to the Backlight Invert-
er Board. The Program determines when the lamp is
turned ON and OFF. It also adjusts the lamp bright-
ness. To increase the average lamp life of 25,000 hours,
the lamp brightness is normally adjusted to 50%. This
brightness level will still allow the display to be vis-
ible. When the Program senses a Keypad key has been
pressed, it adjusts the brightness to 100% (maximum).
The lamp illumination high voltage AC is generated
from 12 VDC or +5 VDC as required by the
manufacturer. Microboard Program Jumper JP5 must
be positioned to provide the required voltage. The mi-
croboard provides the Backlight Enable signal. This
signal turns the lamp ON and OFF. Some manufactur-
ers require this signal to be +12 VDC, others require
+5 VDC. Program Jumper JP4 must be positioned to
provide the required voltage. Further, some applica-
tions require this signal to be a + VDC (+12 VDC or
+5 VDC) to turn on the lamp. Others require this signal
to be 0 VDC to turn on the lamp. Program Jumper JP3
must be positioned to provide the required polarity.
Depending upon the Display manufacturer, the bright-
ness control input from the microboard must be either
a variable voltage or a variable resistance. Microboard
Program Jumpers JP7 and JP8 are used to provide the
The Lamp Dimmer circuit on the microboard is an In-
tegrated Circuit (IC) that is the electrical equivalent of
a 10K ohm potentiometer with 100 positions or steps.
The Program adjusts the position of the potentiometer.
When configured for variable voltage (JP7 and JP8 in-
stalled), the output between Microboard J6-7 and J6-8 is
a 0 to +5.0 VDC signal. Not all applications require the
full 5.0 VDC range. If configured for variable resistance
(JP7 and JP8 removed), the output between Microboard
J6-7 and J6-8 is a 0 to 10K ohm variable resistance.
The OptiView Control Center could be supplied with
any of several approved Displays. Each Display re-
quires a specific Backlight Inverter Board as specified
Figure 48 on page 120 to Figure 49 on
. These boards are individually available as
service replacement parts (the required Backlight In-
verter Board part number is listed on the label attached
to the display mounting plate). However, service re-
placement Displays are provided in a kit (YORK P/N
331-01771-000) that includes the appropriate Back-
light Inverter Board (See
).
SHARP model LQ10D367/368 (031-01774-000) and
LG Semicon LP104V2-W (031-02046-000) displays
require a Backlight Inverter Board 031-01789-000
(See
SHARP model LQ104V1DG61 display (031-02886-
000) requires Backlight Inverter Board 031-02889-000
(See
). These boards generate
a lamp illumination high voltage AC from +12 VDC.
When the Backlight Enable signal is +5 VDC, the high
voltage signal is applied to the lamp. When the Enable
is 0 VDC, the high voltage is removed from the lamp.
SHARP model LQ104V1DG81 (031-03441-000) has
an LED backlight and therefore does not use a Back-
light Inverter Board.