Protector Module (Z801) - Toshiba CN27E90 Technical Training Manual

8. PROTECTOR MODULE (Z801)

CN32E90 employs protector module which combines in one
package protection circuits for X-RAY protection and over
current protection, and error amplifier for +B voltage
detection. This is for the purpose of small size and
standardization of protection circuit, and what were discrete
circuits in conventional chassis are arranged into module.
Equivalent circuit is shown in figure 14-9. A section is error
amplifier for +B voltage detection, B section is over current
protection circuit and C section is X-RAY protection circuit.
D section forces power signal from microcomputer to set in
low level by the signal from protection circuits, and to turn
OFF the power relay and keep it. Actually in case of over
current protection circuit, when over current flows in +B
Q862
R890
3
5
A
Tr1
ZD1
POWER
C470
5V-1
16 15
R9
R2
ZD4
R10
Tr7
R14
D
Tr6
R12
C1
R3
Tr5 R11
7 17
Fig. 14-9 Protector module equivalent circuit
line, Tr8 turns on to supply base current into Tr6 through
ZD4. In case of X-RAY protection circuit, when high voltage
increases abnormally, Tr10 and Tr9 turns on to supply base
current into Tr6 through D3, then this causes Tr6 and Tr5
turn on to make power signal from microcomputer in low
level. Besides, by the positive feedback that turning on of
Tr6 causes Tr7 turn on to make base current flow to Tr6, as
long as 5V is supplied to pin15, Tr5, Tr6 and Tr7 continues
to be on to keep safety. Therefore the operation is not
released by remote control, but continues until AC cord is
pulled and inserted. When this module operates, red blinking
of power LED shows the operation of protection circuit.
R470
+B
R472 R479
6 2 1 14
Tr9
R19
R20
R16 D1
Tr8
D3
B
R15
R21
Pins 4, 8, 9,10: No connection
Pin14: Gate terminal
106
+25V over voltage
protection
+27V over current
X-RAY
protection
+25V
C474
12 13 11
R25 R23
Tr10
R22
C
R26
Protection circuit begins to operate with
1.5V or more of this termianl voltage.