Dell E190Sf LCD Monitor – How enter Service Mode – SMPS schematic
Factory mode – SMPS circuit diagram and working principle – DELL E190s – LCD Monitor
Factory
Mode
With
signal input, press “Power” button to turn off the monitor. Press “Menu” and “Auto/Plus”
buttons together, and then press “Power” button to turn on the monitor.
After
power on, press “Menu” button to call out Main Menu
Pull down to Factory
Reset and choose Factory to enter Factory mode.
Panel:
JT094: Current using panel part number (DELL supply)
Exit:
Exit from Factory mode and back to Reset to Factory Settings.
Auto Color: Automatically calibrate chip ADC parameters by using internal DAC. (Only with Burn-in ON)
Burn In: Enable or disable the Burn-in mode by choosing ON or OFF.
Reset Timer: Reset the “Turn-on time” of the panel to 0H0M.
Color Temp:
The R, G, B of Blue Preset (9300K), Red Preset (5700K) and Normal
Preset (6500K) are generated from scaling chip’s back-end white-balance
program.
Time: Turn-on time of the panel.
Burn-in
pattern: If it is a new monitor without VGA cable plugged in, burn-in pattern
will self-generate automatically. Burn-in pattern will not be stopped until
plugging in the VGA cable. Then, press “Menu” button to call out OSD Main Menu;
pulling down to Factory Reset item and execute All Resetting to disable Bun-in
ON.
Auto
Color Balance (Automatically calibrate chip ADC parameter by using chip internal
DAC.). If it is a new-built set, press “Auto/Plus”
button to execute “Auto Color” at 32gray scale pattern.
Confirm
the following steps to perform “Auto Color Balance”: - Connect the VGA cable
with the standard video pattern generator and display 32gray scale pattern on
the monitor.
-
Press “Power” button to power off the monitor.
-
Press “Menu” and “Auto/Plus” buttons simultaneously; then press “Power” button
to power on the monitor.
-
Press “Menu” button, pull down to Factory Reset and choose “Factory” item.
-
Set Burn In to ON, then execute Auto Color. - With “Auto Color” finished,
return to Reset to Factory Settings OSD and execute All Settings to enable
burn-in OFF.
EDID
(Rewrite EDID data to EEPROM by Fox_VEDID_Programmer) The Write-Protect Pin of
EEPROM is generally pulled up to enable EDID to be read only; EDID cannot be
written at that status.
The following steps enable EDID to be write:
Connect
the monitor and PC via a VGA cable.
Execute Fox_VEDID_Programmer.
- Click “browse” icon to choose a binary file from the PC.
-
Type the “Serial Number” in the dedicated field. Each monitor will have
its own serial number. Then click Enter on the keyboard to jump to next
field.
- Type 1 to 2 characters or digits in “Travel Card SN” field. Then click Enter to start writing EDID to monitor.
- “PASS” will be shown with EDID finished programmed. Please plug out the AC power cord of the monitor to restart.
Upgrade Firmware to Serial via Flash Cable by Fox_VISP_Programmer
Connect the monitor and PC via a VGA cable.
Fox_VISP_Programmer
enables users to upgrade the firmware of the monitor directly through
the VGA cable of a PC. Please follow the steps for reprogramming the
firmware:
-
Click “Select Bin” icon to choose a binary file from the PC. The path of
the selected binary file will be shown in the “Message” text window.
Meanwhile, the checksum of the binary file will be calculated and
displayed.
- Click “Connect” to check if the connection is satisfactory between the monitor and PC.
-
If the connection is ready, click “Auto Programming F2 key” to begin
flashing the firmware. During the flashing process, the motherboard of
the PC will send out tick sound. If the firmware is reprogrammed
successfully, “Command: Fast flash write successful” will be shown in
the “Message” text window. The “successful update” condition will make
the motherboard bring “Do-Re-Mi” sound five times with the interval of
500ms.
With
the process of reprogramming firmware finished, plug out the power cable to
restart the monitor.* The detailed reprogramming procedures will be described in Fox_VISP_Programmer
User Manual.
Diagnostic Test Pattern
1. Press “menu”and “+”simultaneously and hold for 2 sec to enter to the diagnostic.
Check for line defects from the gray color test screen.
2.
Press “+”to advance to the next test pattern - Red color screen. Check
for partial block dot(s) - Red color dead pixel. Continue this for the
Green & Blue color.
3. When in White color test screen, check for white color uniformity and if there white color appears greenish/reddish, etc.
If
you change the M/B, be sure that the U301 and U402 these two components
also changed to the new M/B because there was program inside. If not,
please re-write EDID or upload firmware into serial flash(U402) via VGA
Cable.
If you adjust clock and phase, please do it at condition of Windows shut down pattern.
Confirm the R/G/B color under 32gray scale pattern.
This
LCM is analog interface. So if the entire screen is an abnormal color
that means the problem happen in the analog circuit part, if only some
scale appears abnormal color that stand the problem happen in the
digital circuit part.
If you check the H/V position, please use the crosshatch pattern.
This
LCM support 10 timing modes, if the input timing mode is out of
specification, “Cannot Display this Video Mode” will be displayed on the
screen.
If brightness uneven, repairs Inverter circuit or change a new panel.
If you find the vertical line or horizontal line lost on the screen, please change panel.
If
the self-test pattern is moving on the screen, please check whether VGA
Cable is plugged in the Monitor or PC. If the VGA Cable is plugged in
well, please change another VGA cable.
SMPS (Power Supply Regulator Circuit Diagram)
Inverter Control circuit operations
DC_5V
through R1 and C1 will provide power for U1 on the pin2(VDDA),When the
voltage at VDDA is less than ~3.4V,the IC will enter the lockout mode.
The IC will resume operation when the voltage at pin VDDA exceeds an
approximate 3.8V threshold.
Pin3(SEL) used to select appropriate drive topologies, connecting pin SEL to GED shows the IC in the push-pull configuration..
SSTCMP
(pin14) applys the soft-start function and the loop compensation
funtion.C5 at SSTCMP compensates the feedback loop and provides good
transient response to load changes. When the IC is enabled, it starts
from the stinking mode and the TIMER (pin8) is activated. During lamp
ignition,if
the voltage at pin SSTCMP exceeds an approximate 2.0V threshold, the
drive frequency will switch from stinking frequency to the operation
frequency, The striking frequency is determined by (R4& R5)
connected to Pin 4(RT1)and Pin5(RT). The operating frequency is
determined just by R4.
Applying
a voltage level greater than 2V from IF BD to pin6(PWM) can enable the
IC, Once the voltage less than ~1.0V for longer than 20ms will disable
the IC.
Once
the lamps are ignited and the voltage at pins
ISEN1(pin9),ISEN2(pin10),OLP1(pin12),and OLP2(pin13) all exceed
approximately 0.8V,the IC enters the normal operation mode and the PWM
dimming control is activated. During start up, ISEN1 (pin9and pin10)
senses the voltage on the transformer secondary. If no current is sensed
approximately 2 seconds, U1 shuts off. re used to limit current. C3 is
used to dump noise.
DRV1
and DRV2 of U1 are used to drive Q1. DRV1 and DRV2 are controlled by
build-in PWM IC. Q1 is switched which has two build-in IGBTs. The
working principle of circuit of T1, the same to circuit of Power.
The
voltage signal on negative pole of D1 sensed through R7/R8 comes to
Pin11 of U1 VSEN (Lamp Current Detection & Control). The CCFL
current is detected through R12/R21 and reaches a regulated value. The
CCFL current detected at resistor R12/R21 is converted to a voltage
level and input to the ISEN1/2 Once the CCFLs are ignited and current is
sensed through resistor R12/R21, performs the loop compensation
function. The voltage at IC pin12 controls the drive duty cycle of the
power MOSFETs to regulate the CCFL current.
Output Circuit and Protection Circuit operations
The
transformer (T1) secondary winding leakage inductance and output
capacitance(C22) forms a lower pass filter, which converts the
square-wave driving signal into a sinusoidal output voltage signal for
CCFL.
The
over-voltage protection feature is implemented by using an external
capacitor devider(C20/C21) to sense the output voltage. The divide-down
voltage signal is sent to the IC Pin11 (VSEN) ,thus regulating the
output voltage at the transformer secondary.
If a
CCFL is removed, fails or damaged during normal operation, CCFL current
is no longer sensed and the voltage on ISEN1/ISEN2 drops. Once the
voltage at the ISEN1/ISEN2 pin is less than the lamp” on” threshold, the
shutdown timer is activated. The IC maintains the output voltage for
approximately 2-3seconds and once the timer reaches a threshold of
approximately 3V, the IC will shutdown.
To restart the IC, either toggle the SST_CMP pin or recycle the power on the VDDA pin.
High Voltage to Low Voltage Control Circuit
D850 is a rectifier in which there are 4 build-in diodes, inverting AC to DC.
C854
is used to smooth the wave from rectifier. R852 is a fuse resistor to
protect the following circuit when inrush current is too large.
U850
is a current-mode PWM controller with excellent power-saving operation,
It features a high-voltage current source to directly supply the
startup current from bulk capacitor and further to provide lossless
startup circuit. Max start-up current for U850 is 100 uA, When current
flow from the bulk capacitor C854 through R843 and R842 gets to HV pin
to start up U850, Meanwhile, the VCC supply current is as low as 100 uA
thus most of the HV current is utilized to change the VCC capacitor C855
Whenever
the Vcc voltage is higher than UVLO (16V), the GATE pin will output
signal to drive the power MOSFET(Q850), the high-voltage current source
is off and the supply current is provided from the auxiliary winding of
the transformer PIN5.
When
U850 begins to operate Pin8 of U850 will output square wave to drive
Q850, then the main current flow get to GND bypassing through T850,
Q850. Because of the change of current flow, wires in the other side of
T850 will induct current. In the same time, the current inducted by
wires which connected T850 Pin 1 and Pin 3, with components of D852,
R856 and C855 ,will be supplied to U850 for normal operating.
The
typical current mode PWM controller feedbacks both current signal and
voltage signal to close the control loop and achieve ragulation.U850
detects the Q850 current from I sense pin which max voltage is set as
0.85V, then the Q850 current can be calculated as: I
peak=0.85V/R869,When the sense voltage across the sense resistor R869,
reaches the threshold voltage over 0.85V, the output GATE drive will be
turned off. R849 and C846 is used to avoid the Isen pin damaged by the
negative turn-on spike.
The
voltage feedback signal is provided from the TL431(I851) through the
I850 to the COMP pin. When the voltage on COMP pin is lower than
1.2V,the IC will turn off.
When
Q850 is turned off, the main current flow will be consumed through
D851, C875, R880, this will prevent Q850 from being damaged under large
current impulse and voltage spike.
RT pin is to program the switching frequency ,by connecting R846 to ground to set the switching frequency,f=(65.0/R846)*100(KHz)
DC12Vand
DC 5V Output Circuit and Feedback circuit
D854
is used to rectify the inducted current. R862 and C861 are used to store energy
when current is reversed. The parts including C862, C865 and L852 are used to
smooth the current waves that are from D855, then 13V voltage is supplied.
D856 and D857 are SCHTKY diodes used to rectify the inducted current.C866 and R866 are used to store energy when current is reversed, The components including C864,C874,C875,L851 and C876 are used to smooth the current waves, then DC+5V voltage is supplied. F851 is used for OCP for the LPS test.
DC 5V supply voltage feed back to PWM controller U850 via R861,R860,R859,C859,I851,R857, R863 used to control the voltage feedback loop.
D856 and D857 are SCHTKY diodes used to rectify the inducted current.C866 and R866 are used to store energy when current is reversed, The components including C864,C874,C875,L851 and C876 are used to smooth the current waves, then DC+5V voltage is supplied. F851 is used for OCP for the LPS test.
DC 5V supply voltage feed back to PWM controller U850 via R861,R860,R859,C859,I851,R857, R863 used to control the voltage feedback loop.