On-Board Platform Supply; Aurea Sets; 47" Sets; Audio Class-D Amplifiers - Philips 32PFL9432/98 Service Manual

EN 170 9. Q528.1A LA
ON STATE
OFF STATE
Figure 9-9 Principle of Buck Converter
Figure "Buck converter - application" describes the application
which is used in this platform.
18V -> 12V DC-DC converter
7402
+18V
2020
+30V
Gate driver
Figure 9-10 Buck converter - application
In diagram A3 the DC-DC converter which is built around the
Buck converter is depicted. In this application, the controller
(item 7401) controls the gate driver (built around item no. 7403,
7404, 7405 and 7407). Transistor 7403 switches the gate of the
MOSFET (item 7402) "on", and 7405 switches it "off".
Transistors 7404 and 7407 avoid cross-conductance of the
driver. The output of the gate driver circuitry can be measured
at testpoint I604. An "low-voltage lock-out" circuitry is built
around item no. 7406 and activates when the input voltage of
+18 V drops below 15 volt.
An over-voltage protection circuitry is built around item no.
6020 and 6018 and will activate if the feedback circuitry is
defect (see diagram A2).
A primary over-voltage protection is performed by item no.
7307 (opto-coupler) (see diagram A1) and will activate in case
the primary input voltage (mains) is too high. The software will
detect an incorrect signal on the Power-Good line and the TV
will go into protection.
An secondary over-current protection circuitry is built around
item no. 2014 and 3021 (diagram A2). If a short-circuit occurs
in the output circuitry (+12 V, +24/295 V), the switching
frequency of the DC/DC converters will increase. This means
that the soft-start voltage on pin 11 of the resonant mode
controller (item 7001) will be "low" and the output current will
reduce.
The following signals interface with the SSB via connector
1P11 (see diagram A2):
• DIM-control: adjusts backlight intensity (pulse-width
modulated signal of 3.3 V).
Circuit Descriptions, Abbreviation List, and IC Data Sheets
H_16770_108.eps
3407
5401
2402
6401
Controller
7401
H_16770_107.eps
• Power-Good (described above).
• Light on_off: switches the LCD backlight (0 - 3.3 V).
• Boost (fixed: ór 3.3 V ór left "open" depending on
commercial request or display specification).
• Stand-by: stand-by signal and 5.2 V from SSB to switch
relay on Power Supply Unit on/off.
9.3.3

Aurea sets

The Aurea sets come with an additional, serviceable Standby/
Audio Panel. Refer to diagrams AP for details.
The panel inputs:
260307
• 300 V DC (rectified mains)
The panel outputs:
• 9 V / 7 A for AmbiLight modules
2 × 12 V / 1.4 A for audio class-D amplifiers.
•
The outputs for audio class-D amplifiers are protected against
malfunctioning of the hardware (DC-PROT input from class-D
amplifiers).
+12V
Compared with the Standby/Audio Panel used in the previous
Jaguar chassis (chassis BJx.x, FJx.x), it can be stated that only
the auxiliary supply part has been reused/adapted. The rest is
newly developed.
In the supply part, compared with Jaguar chassis some extra
power resistors have been added:
• 9 V AmbiLight supply: to ensure minimum load
• 2 x 12 V Audio supply: to limit the maximum audio supply.

Audio Class-D Amplifiers

In Aurea sets (with Standby/Audio Panel), the audio class-D
amplifiers are located on this panel. Compared to the audio
class-D amplifiers used in the previous Jaguar chassis, only
extra filtering has been applied for better acoustics. The rest
has been re-used.
9.3.4

47" Sets

260307
The 47" sets in this chassis come with a buy-in Sanken Display
Supply unit and is a black-box for Service. When defective, a
new panel must be ordered and the defective panel must be
sent for repair, unless the main fuse of the panel is broken.
Always replace a defective fuse with one with the correct
specifications! This part is available in the regular market.
The supply unit works together with the on-board platform
supply (see section "On-Board Platform Supply").
Two versions of this supply unit can be used in this platform:
• Output voltage of +295 V for the scanning backlight
displays (not in US region)
• Output voltage of +24 V for all other displays.
Always refer to the Spare Parts list for the correct order
number!
The supply unit delivers the following voltages to the chassis:
• Mains voltage (filtered) for SSB (connector 1P02)
• +395 V DC (connector 1P22)
• Scanning backlight display: +295 V DC (connectors 1P05/
1P06)
Non scanning backlight display: +24 V DC (connectors
1319/1316)
• +12 V DC on connectors 1M09, 1M12 and 1P15.
When all these voltages are present, the Power-Good signal
becomes "high" (+5 V) (connectors 1P10.2 and 1P11.2).
9.4

On-Board Platform Supply

In this platform, an on-board platform supply has been
foreseen. This means that the mains voltage, after filtering, is
fed to the SSB.