DOWNLOAD Panasonic E3 / E3D / Chassis Service Manual ↓ Size: 259.93 KB | Pages: 20 in PDF or view online for FREE

Model
E3 E3D Chassis
Pages
20
Size
259.93 KB
Type
PDF
Document
Service Manual / Other
Brand
Device
TV / E3/E3D
File
e3-e3d-chassis.pdf
Date

Panasonic E3 / E3D / Chassis Service Manual / Other ▷ View online

10
7. 
Protection   
Relay
Protect
A2/W1
7
Q7115 <R>
Q7117 <G>
Q7118 <B>
CRT STOP
Q1030(INV)
RL6701
Q6751
+22V Short
circuit
D7755
-12V Short
circuit
+12V Short
circuit
+22V Over
current
Q7543
Q7545
-22V over
current
210V Short
circuit D863
140 over
current  R862
23V short
circuit D859
15V short
circuit D855
Q848
-22V Short
circuit
D7549
Q849
Q846
8V short
circuit D853
+8V(H) short
circuit D870
-15V short
circuit D850
D7577<A>
D7560<A>
D500<B>
D514<B>
D400<C>
D868<B>
D869<B>
D861<B>
Standby LED
D1004
<CP-Board>
EHT
D513
V-
Break
IC451
FB
T
FBT
Pin1
ABL
<F-Board>
X-ray
IC411
<D-board>
LED
Pin 7 of IC1101 input
Holddown
à 1.354-2.308V
Shutdown
à 2.554-3.508
Abnormal
à 3.754-5.000V
Pin12 of IC1101 output
<A>
<B>
<C>
   
4sec
Q511
Q400
Q503
E8
4
12
27
7
D11
8
P11
4
11
Purpose
To prevent smoke, fire and the radiation of X-rays due to
abnormally high voltages by using detection circuits (listed
below) to instantly turn off the power in the event of a
problem. Also, depending on the circuit, the projection
tubes can be damaged in the event of a problem; therefore,
there is also a circuit that informs the blanking circuit when a
problem arises so that the video signals to the cathodes can
be blanked.
There is a circuit that prevents the power being turned on by
remote control once a problem is detected as follows;
Protection Circuit
1) Convergence –22V short-circuit (LED blink one time)
2) Convergence +22V short circuit (LED blink one time)
3) Convergence –12V short-circuit (LED blink one time)
4) Convergence +12V short circuit (LED blink one time)
5) Convergence +12V short circuit (LED blink one time)
6) Convergence +22V over current (LED blink one time)
7) Convergence –22V over current (LED blink one time)
8) Convergence –22V short-circuit (LED blink one time)
9) X-ray (LED blink two times)
10) Extra High Tension (EHT) (LED blink two times)
11) V-stop (LED blink  three times)
12) +210V short circuit (LED blink two times)
13) +140v over current (LED blink two times)
14) +23V short circuit (LED blink two times)
15) +15V short circuit (LED blink two times)
16) +8V short circuit (LED blink two times)
17) +8(H)V short circuit (LED blink two times)
18) -15V short circuit (LED blink two times)
Operation.
Protection line of each circuit is connected to IC1101 pin 7.
When some of these pins go to “H”, this abnormal
information is informed to IC1101 (MPU) .
Then RELAY output pin No.27 of IC1101 voltage to “H”,
Q1030 turns ON, Q6751 base voltage drops to LOW and
trips the power supply relay  RL6701. In such cases, the
main unit power lamps blinks to indicate that a protection
circuit is operating. (refer to LED blink time)
12
7.RGB Out Blanking
RGB Out Blanking
The purpose of The RGB blanking circuit is prevents burn in
of the phosphor of CRT.
There are three blanking transistors, Q7730 (blue), Q7728
(green) and Q7729 (red) to cut off the beam of the CRTs.
The collectors and bases of the three transistors are
connected together so that if one drive fails, all of the beams
will be turned off.
The collectors of each of the three transistors will go low
turning off the RGB drive transistors.
The RGB transistors are used in the horizontal blanking,
vertical stop blanking, vertical over deflection, power off
blanking and protection circuits.
If the power off blanking and protection circuits is activated,
the PTV is turned off at the same time.
Horizontal Blanking
During horizontal retrace, a series of horizontal pulses is
supplied from horizontal output transistor Q551 to the base
of Q7738 for horizontal blanking, to prevent the projection
tubes emitting light during the fly-back interval.
Vertical Stop Blanking.
If vertical deflection stops, the remaining horizontal line will
burn the phosphor of each CRT. The vertical stop blanking
circuit is designed to activate the blanking circuit by cutting
off the RBG drive to the CRTs.
The vertical pulse from  IC451 vertical out pin8 is applied as
forward bias to the cathode of D402. During normal
operation, the pulse is applied to the base of Q400, keeping
Q400 turned on. If the V-pulse is not present to the cathode
of D402, Q400 turned off.
The collector voltage of Q400 increase, and supplies
voltage to the RGB blanking circuit, which turns off the
CRTs.
Vertical Over Deflection Blanking
If during the deflection period the electron beam goes
beyond normal range and hits the neck of the CRT (over
deflection), the beam can burn through and destroy the
CRT. The over deflection blanking circuit is designed to
prevent this.
IC508 is composed of comparator. When abnormal level
V-pulse input, the pin 4 would go high and applied to base
of Q7738, it will turn on Q7738, to control the RGB out
blanking circuit.
H-pulse
IC1101
MPU
59
60
CLK
DATA
16
1
2
B BLK
IC7707
DAC
9
G BLK
R BLK
14
15
+9V
+9V
Q7730
Q7729
Q7728
1
2
B
9
G
R
IC7703
RGB out
Q7718
Q7717
Q7715
CRT-B
CRT-G
CRT-R
H-out
Q551
V-pulse
Protection Detection
IC508
Vertical over
protection
Relay
Q7738
Q773
13
- memo -
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