Samsung Plasma TV – Working principle and troubleshooting procedure
Function Description by board
SMPS(Switching Mode Power Supply)
: It is the supplier to provide voltage and current to work the drive voltage and panel in each board. X-MAIN BOARD
: It makes the drive wave form by switching FETs to Timing Controlle coming from logic-board and
supplies X electrode of panel with the drive wave form via connector. Y-MAIN BOARD
: It makes the drive wave form by switching FETs to Timing Controller coming from the logic-board and provides Y electrode of panel with the drive wave form via Scan Driver IC on Y buffer board in order. LOGIC MAIN BOARD
: It process image signal and performs buffering of the logic-main board (to create XY drive signal and output) and the address driver output signal. Then it supplies the output signal to the address driver IC(COF Module).
: It is the supplier to provide voltage and current to work the drive voltage and panel in each board. X-MAIN BOARD
: It makes the drive wave form by switching FETs to Timing Controlle coming from logic-board and
supplies X electrode of panel with the drive wave form via connector. Y-MAIN BOARD
: It makes the drive wave form by switching FETs to Timing Controller coming from the logic-board and provides Y electrode of panel with the drive wave form via Scan Driver IC on Y buffer board in order. LOGIC MAIN BOARD
: It process image signal and performs buffering of the logic-main board (to create XY drive signal and output) and the address driver output signal. Then it supplies the output signal to the address driver IC(COF Module).
LOGIC BUFFER(E,F,G)
: It delivers
the data signal and control signal to the COF.
Y-BUFFER (Upper,Lower)
: It is the board to impress the scan waveform on the Y board and consist of 2 boards (upper board and lower board).
8 Y-buffers are fixed at the scan driver (STV7617 of STC corp. : 64 or 65 Output). AC Noise Filter
: It has functions to remove noise(low frequency) coming from AC LINE and prevent surge. It gives serious effects on the safety regulations (EMC, EMI) according to AC filter. COF(Chip on Flexible)
: It impress the Va pulse to the address electrode in the address section and forms the address discharge by electric potential difference with scanning pulse to be dismissed by the Y electrode. It is made in the form of COF and one COF consists of 4 Data Drive IC (STV7610A :96 Output), otherwise single scan is made of 7 COF
: It is the board to impress the scan waveform on the Y board and consist of 2 boards (upper board and lower board).
8 Y-buffers are fixed at the scan driver (STV7617 of STC corp. : 64 or 65 Output). AC Noise Filter
: It has functions to remove noise(low frequency) coming from AC LINE and prevent surge. It gives serious effects on the safety regulations (EMC, EMI) according to AC filter. COF(Chip on Flexible)
: It impress the Va pulse to the address electrode in the address section and forms the address discharge by electric potential difference with scanning pulse to be dismissed by the Y electrode. It is made in the form of COF and one COF consists of 4 Data Drive IC (STV7610A :96 Output), otherwise single scan is made of 7 COF
Operation Description on SMPS
1. Overview
SMPS used in PDP 42" developed into the compact-sized with high efficiency. The asymmetrical half bridge and the fly-back converter are applied into all output. To comply with the harmonic restrictions, it takes the power factor improvement circuit, which converts AC into the high DC and uses as the input of another converter controller. 2. Input controller
SMPS works in whole section of AC 90~264V. It is possible to start in the AC 90 and can restart with new input voltage, even in interruption of electric power. STD_5V comes out when AC is impressed 3. Output Controller
Given SMPS have 15 output voltages. The following shows the specification of output voltage and output current in case of their successive drive.
SMPS used in PDP 42" developed into the compact-sized with high efficiency. The asymmetrical half bridge and the fly-back converter are applied into all output. To comply with the harmonic restrictions, it takes the power factor improvement circuit, which converts AC into the high DC and uses as the input of another converter controller. 2. Input controller
SMPS works in whole section of AC 90~264V. It is possible to start in the AC 90 and can restart with new input voltage, even in interruption of electric power. STD_5V comes out when AC is impressed 3. Output Controller
Given SMPS have 15 output voltages. The following shows the specification of output voltage and output current in case of their successive drive.
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Over-voltage protection
It has circuit to maintain normal voltage, additionally with circuit for
sensing overvoltage, so it means any overvoltage does not give impacts
on other output controller. SMPS prevents overvoltage in the latch mode.
VS(85V) works protection function more than 100V, over 94V for
VA(75V), over 8.2V for D6V, over 4.7V for D3.3V
Short circuit and over-voltage protection
It forms definition that in the short circuit of output controller the
output impedance is lower than 300mohm. If the VS output have a short
circuit in case of given SMPS, SMPS stops its working. Even in the case
of short circuit between main output and STD_5V, SMPS does not break
down.
When the short circuit is removed, it restarts
AC-DC Converter
It converts AC into DC by using the power factor improvement circuit.
This converter was designated to control the high frequency noise, with
the function to improve the power factor. This part becomes input
controller of another constant-voltage.
Auxiliary Power
It is the part to supply power of mycom for remote control. When the power is on, it will work, which means that MICOM is on standby. This output part is standby voltage. When the power-on signal from remote control impress, it works main power panel of SMPS via standby voltage.
It is the part to supply power of mycom for remote control. When the power is on, it will work, which means that MICOM is on standby. This output part is standby voltage. When the power-on signal from remote control impress, it works main power panel of SMPS via standby voltage.
Configuration of VS output
Major part of PDF SMPS outputs 85V 5A. It takes asymmetrical half bridge converter and connects 2 converters with 85V output in parallel, which increases efficiency than one 85V converter, on the other hand, decreases its size.
Major part of PDF SMPS outputs 85V 5A. It takes asymmetrical half bridge converter and connects 2 converters with 85V output in parallel, which increases efficiency than one 85V converter, on the other hand, decreases its size.
PWM Part
It uses PWM part of ML4824, but there are some points to take cautions. As this part is synchronized with the PFC part, PWM wave in the current mode drive is induced via the current sensor resistance or current transformer, and shows the current flowing in the output controller.
It uses PWM part of ML4824, but there are some points to take cautions. As this part is synchronized with the PFC part, PWM wave in the current mode drive is induced via the current sensor resistance or current transformer, and shows the current flowing in the output controller.
Operation Explanation of Driving
Circuit
1. Overview of Driver Circuit 1) Definition of Driver Circuit
The driver circuit division drives the panel with the proper wave form (high voltage pulse) to develop image on the outside terminal division (X electrode group, Y electrode group, Address electrode). High voltage switching pulse is made by MOSFET combination. 2) Working Principle of Driver Circuit
To develop image on the PDP, the voltage should be impressed into the X, Y and ADDRESS electrodes (which are component of each pictorial element) under the proper conditions. The driver wave form which is currently applied to is ADS (Address & Display Separate: Driving method to work by dividing address and constant-current section ) Based on this method, the discharge to be done in the pictorial element of PDP can be divided into 3 types as follows.
1. Overview of Driver Circuit 1) Definition of Driver Circuit
The driver circuit division drives the panel with the proper wave form (high voltage pulse) to develop image on the outside terminal division (X electrode group, Y electrode group, Address electrode). High voltage switching pulse is made by MOSFET combination. 2) Working Principle of Driver Circuit
To develop image on the PDP, the voltage should be impressed into the X, Y and ADDRESS electrodes (which are component of each pictorial element) under the proper conditions. The driver wave form which is currently applied to is ADS (Address & Display Separate: Driving method to work by dividing address and constant-current section ) Based on this method, the discharge to be done in the pictorial element of PDP can be divided into 3 types as follows.
Address Discharge: to form the
wall voltage within pictorial element by providing lighting pictorial element
with information(impressing data voltage)
: It is the discharge produced by difference between the positive electric potential of address electrode (normally, Va impressed voltage of 70~75V +Positive Wall charge) and negative electric potential of Y electrode (GND level impression+ Negative Wall charge)
: It is the discharge produced by difference between the positive electric potential of address electrode (normally, Va impressed voltage of 70~75V +Positive Wall charge) and negative electric potential of Y electrode (GND level impression+ Negative Wall charge)
Constant-current Discharge:
It is
the display section to form discharge voluntarily with the help of wall voltage
formed by address discharge. (It makes optical power to create image)
: It is the Self Sustaining Discharge made by combining the electric potential of coherent pulse, normally 160-170Volt, which alternates the X electrode with Y electrode in the sustain section, with the wall voltage according to the pictorial element condition changed by if the former discharge exists or not. That is to say, it works according to Memory characteristic (it means that former working condition defines the current condition) as the basic feature of AC PDP.
If the wall voltage formerly exists in the pictorial element (i.e., the pictorial element is on), the discharge makes forms again because the voltage higher than one of the discharging starting time is impressed by combination of the wall voltage and of the next impressed constant-current. While if the wall voltage does not exist in the pictorial element (i.e., the pictorial element is off), the discharge does not form because the voltage could not reach to the level of the discharging starting time, only with constant-current.
: It is the Self Sustaining Discharge made by combining the electric potential of coherent pulse, normally 160-170Volt, which alternates the X electrode with Y electrode in the sustain section, with the wall voltage according to the pictorial element condition changed by if the former discharge exists or not. That is to say, it works according to Memory characteristic (it means that former working condition defines the current condition) as the basic feature of AC PDP.
If the wall voltage formerly exists in the pictorial element (i.e., the pictorial element is on), the discharge makes forms again because the voltage higher than one of the discharging starting time is impressed by combination of the wall voltage and of the next impressed constant-current. While if the wall voltage does not exist in the pictorial element (i.e., the pictorial element is off), the discharge does not form because the voltage could not reach to the level of the discharging starting time, only with constant-current.
Erasing discharge:
To selectively perform the address discharge for respective pixel,
pixels of all panels must be on same conditions (same wall charge state
and space charge state). Therefore the erasing discharge zone is
important factor to obtain driving margins.
There are various methods such as application of log waveform but the
wall voltage control method by the Ramp Waveform is now widely applied.
: The purpose of initialization (Erasing) discharge is to make wall
voltage within the the whole of Pixels. In other words, the erasing
discharge must make difference between wall voltages uniform depending
on whether or not the sustain discharge exists in the previous state.
Namely it must remove the wall voltage formed by the sustain discharge
and supply ions or elements by causing discharge for removing the wall
voltage. In the other words, To remove the wall voltage, limit the time
when polarity of the wall voltage is reversely charged by causing
discharge or prevent polarity form being reversely charged by supplying
appropriate quantity of ions or
elements through forming weak discharge [low voltage of erasing]. There
are two types of the weak discharge
[low voltage]as known so far.
1) Log Waveform adopted by the F-company
2) Weak
erasing discharge by the Ramp Waveform largely adopted by Matsushita Company,
etc. Outside applied voltage is adjusted depending on difference of wall
voltage within Pixel, since discharge is formed when the sum of the existing
wall voltage remained and the voltage on a rising waveform exceed the driving
beginning voltage, by slowly applying the rising slope of the erased waveform
for these two methods. In addition, weak discharge is formed since the strength
of applied voltage is small.
Essential factors for driving board operation
- Supplied from power board and the optimum value may somewhat differ from the below cases.
● Vs : 85V - Sustain
● Vset : 60V ~ 70V - Y Rising Ramp
● Ve : 110V - Ve bias
● Vscan : 70V ~ 80V - Scan bias
● Vdd : 3.3V - Logic signal buffer IC
● Vcc : 15V - FET Gate drive IC
● Logic Signal
: Supplied from logic board
: Gate signal of each FET
Explanation of Function per Pulse
● Y Rising Ramp Pulse
Outside voltage of about 390V~400V is applied to the Y electrode in the Y
Rising Ramp zone, and weak discharge begins if respective gap voltage
equals to the discharge beginning voltage. Negative Wall charges
accumulate on the Y electrode and the Positive Wall charges on the X
electrode in the whole while weak discharge is maintained.
● Y Falling Ramp Pulse
Most of Negative Wall charges accumulated on the Y electrode by the X
bias of about 200V are used to remove Positive Wall charges in the Y
Falling Ramp zone, and most of Positive charges accumulated on the (0V)
Rising Ramp zone toward the address electrode are maintained, having
distribution of wall charges beneficial for the subsequent address
discharge
Y Scan Pulse
Y scan pulse is called as injection pulse, and selects the Y electrode
one by one (Line-at-a-time). In this case, Vscan is called as Scan
bias. For the electrode line with the Vscan voltage applied, voltage of
about 70 Volt (Vscan) is applied, and voltage of 0 Volt(GN0) is applied.
However, since Negative Wall charges accumulate on the Y electrode by
the application of Ramp pulse and Positive Wall charges accumulate on
the address electrode, voltage of more than the discharge beginning
voltage is applied to the cell where address pulse(70V~75V) is allotted
and thus address discharge occurs. Address time of the PDP is very long
since both scan pulse and data pulse must be applied in line at a time.
● 1st Sustain Pulse
The Sustain Pulse always begins from the Y electrode, it is because
Positive Wall charges are formed on the Y electrode if address discharge
occurs. The wall charges formed by the address discharge are less than
those for the sustain discharge, and thus the strength of the initial
discharge is weak. Sustain discharge usually become stable after 5~6
times of discharge depending on structure of electrode and environment.
Therefore, the initial long sustain pulse is intended to form the
initial discharge stable and form the wall charges much as possible as.
Y buffer
- To check whether there is failure of the Y Main, firstly check normal operation of the Y buffer.
- After separating both the Y Main and the Y buffer connector,
- Check forward voltage drop of 0.4V ~ 0.5V by diode check between OUTL and OUTH.
- In addition, resistance between both ends is also more than several kΩ.
- To check whether there is failure of the Y Main, firstly check normal operation of the Y buffer.
- After separating both the Y Main and the Y buffer connector,
- Check forward voltage drop of 0.4V ~ 0.5V by diode check between OUTL and OUTH.
- In addition, resistance between both ends is also more than several kΩ.
Y Main
- After connecting both the Y Main and the Y buffer, check that output of one of OUT1~8 of the Y buffer is done as follows in application of power
- After connecting both the Y Main and the Y buffer, check that output of one of OUT1~8 of the Y buffer is done as follows in application of power
X Main
- Check output of the TPOUT on the X board is done as follows in application of power
- Check output of the TPOUT on the X board is done as follows in application of power
Definition of Name and Terms on
Logic Board.
Explanation of Logic Board
Logic board is composed of a logic main board that generates and outputs the address driver output signal and the XY driving signal by processing image signal, and a buffer board that buffers the address driver output signal and delivers it to the address driver IC (COF Module).
Logic board is composed of a logic main board that generates and outputs the address driver output signal and the XY driving signal by processing image signal, and a buffer board that buffers the address driver output signal and delivers it to the address driver IC (COF Module).
Trouble Shooting procedure for any PDP Set
