Dell E1909W Service Manual page 11

D854&D855 are used to rectify the inducted current. C862 are used to store energy when current is
reversed. The parts including C863 is used to smooth the current waves that are from D854&D855, and then
24V voltage is supplied.
D856&D857 are used to rectify the inducted current. C873 are used to store energy when current is
reversed. The parts including C856, C857, C858 ,C876 and L854 are used to smooth the current waves that
are from D856&D857, and then 5V voltage is supplied.
24V and 5V supply voltage feed back to PWM controller U850 via R871, R872, R868 and
I850,I851.R860,C859 and C871 used to control respond time.
LD7552B are implemented an OVP function on Vcc.Whenever the Vcc voltage is higher than the OVP
threshold voltage,the output gate drive circuit will be shutdown simultaneously thus to stop the switching of
the power MOSFET until the next on.
2.3 I/F Board Circuit (see the Attachment 2- Schematic)
2.3.1 RGB CAPTURE
- Signal RED,GREEN,BLUE input through CN102 #1,#2,#3, Stop DC via C113, C114 and C115, and
then enter into U105 (TSUM5PEHJ-LF-2) analog input PIN #28,#25,#23, and then
TSUM5PEHJ-LF-2 deals with signal internally. D103, D104, D105 are ESD protector to prevent
U105 from ESD.
- Signal DDC_SCL (series clock) inputs via CN102#15, and then passes through ZD106 for ESD
protection, goes into EDID EEPROM IC U103 #6.
- Signal DDC_SDA (series data) inputs via CN102#12, and then passes through ZD103 for ESD
protection, goes into EDID EEPROM IC U103 #5.
- Signal TTL vertical sync. (Vsync) inputs via CN102 #14, and then clamped by ZD105 Zener, passes
through R134, and then goes into IC U105 (TSUM5PEHJ-LF-2) #33.
- Signal TTL horizontal sync. (Hsync) inputs via CN101 #13, and then clamped by ZD102 Zener,
passes through R133, and then goes into IC U105 (TSUM5PEHJ-LF-2) #32.
- CN101#5 is defined as cable detect pin, this detector realize via R121 and U104#36, and D102 is
ESD protector.
- U103 +5V is supplied by PC via CN102#9 with ZD102 for ESD protection, or supplied by Monitor
self via D106
- U103 is an EEPROM IC which is memory and EDID data saved in it.
2.3.2 DVI CAPTURE
- Differential Signal input RX0+,RX0-,RX1+,RX1-,RX2+,RX2-,RXC+,RXC- through CN201
#18,#17,#10,#9,#2,#1,#23,#24 via R206,R205,R204,R203,R202,R201,R207,R208 enter into U105
(TSUM5PEHJ-LF-2) Digital input terminal #16,#15,#13,#12,#10,#9,#18,#19, and then
TSUM5PEHJ-LF-2 deals with signal internally. D206, D207, D204, D205, D202, D203, D208,
D209 are ESD protector to prevent U105 from ESD
- Signal DDC_SCL (series clock) inputs via CN201#6, and then passes through ZD204 Zener for ESD
protection, via R209, goes into EDID EEPROM IC U201 #6.
- Signal DDC_SDA (series data) inputs via CN201#7, and then passes through ZD203 Zener for
ESD protection, via R210, goes into EDID EEPROM IC U201 #5.
- CN201#15 is defined as cable detect pin, this detector realize passes through R216 ,go into U105#49,
and D210 is ESD protector.
- U201 +5V is supplied by PC via CN201#14 through D201, or supplied by Monitor self via D201.
- U201 is an EEPROM IC which is memory and DVI input EDID data saved in it.
2.3.3 Buttons Control
- Button "Power" on front bezel connects to U105 (TSUM5PEHJ-LF-2) #4 through CN104 #8, U105
#4 is defined as power on/off.
- Button "+" on front bezel connects to U105 (TSUM5PEHJ-LF-2) #120 through CN104 #2,
U105#120 Voltage is defined as "Plus".
- Button "-" on front bezel connects to U105 (TSUM5PEHJ-LF-2) #121 through CN104 #3, U105
#121 Voltage is defined as "Minus".
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Service Manual