Table of Contents
Advertisement
5
QQ
3 7 63 1515 0
Detailed Descriptions on the Protection Operations
Power-ON muting operation
• The voltages at R558 and C553 of the time-constant circuit are compared with the reference voltage at the difference
amplifiers, and muting will be released when those voltages exceed the threshold levels.
Two difference amplifiers are provided, with the slightly different threshold levels (approx. 50 mV = R568 voltage drop,
50 ms). The output relay is first set to ON then the input relay is set to ON.
Power-ON surge killer operation
• When the voltages at R686 and C682 of the time constant circuit exceed approx. 7.2 V (-12 + D551 + 1.2), Q682 and Q683
are set to ON, the relay of the surge killer circuit is activated, and the surge killer resister is short-circuited.
• When the unit is turned off, Q681 is set to ON, Q682 and Q683 are set to OFF, and the relay of the surge killer circuit is
released.
Overload-detection operation
• The overload status (approx. 0.5 ohm or less) on the + side is detected at Q501 and Q521, and that on the - side is detected
at Q502 and Q522. Detection of an abnormality is retained via the latch circuit that consists of Q552 and Q553.
Then Q554 together with Q555 is set to ON, C553 is rapidly discharged, the subsequent differential circuit and output/input
relays at the relay drive circuit are activated, then signals are set to OFF.
• The white LEDs go dark when Q563 is set to OFF, and the red LEDs light when Q564 is set to ON.
• To prevent arc discharge when the output relay is set to OFF, approx. 4-ms time-constant circuits are provided with the C555
and R565 circuits so that the output relay is activated later than the input relay.
Output DC detection operation
• Audio signals are eliminated at the LPF that consists of R508, R509, C503, C504, and R528, R529, C523 and C524, and +
DC output level is detected at Q503 (Q523) and - DC output level is detected at Q504 (Q524). Detection of an abnormality is
TE
L 13942296513
retained via the latch circuit that consists of Q552 and Q553. The same operations as those for overload detection will then
follow.
• The detection levels are Approx. Vbe*(R509/(R508 + R509)).
• The formula for the equivalent cutoff frequency of the LPF is as follows: Frequency determined by (R508 (R528)//R509
(R529)) and (C503 (C523)/2) multiplied by (output peak voltage/detection level), given that C503 (C523) = C504 (C524).
Temperature-detection operation
• For temperature detection, use a TH490=PTFM04BD471Q2N34B0 (100 ºC) type Posistor from Murata Manufacturing that
can be secured to the heat sink with screws. The characteristics of this thermistor are as follows: at 80 ºC, typical 100 ohms
or less; at 90 ºC, 330 ohms or less (typ. 100 ohms); at 100 ºC, 470 ohms or higher (typ. approx. 1.5 k-ohms).
• In the first detection step, when the resistance value at the Posistor becomes 400 ohms or higher at a preset temperature of
90-95 ºC, Q541 is set to ON, Q565 is set to OFF, and the white LEDs go dark. Instead, Q564 is set to ON and the red LEDs
light.
• In the second detection step, when the resistance value at the Posistor becomes 1.4 k-ohms or higher at a preset
temperature of approx. 100 ºC, Q542 is set to ON. Detection of the abnormality is retained via the latch circuit that consists
of Q552 and Q553. The same operations as those for overload detection will then follow.
• If the first detection step is activated, lower the output level and the ambient temperature. Q541 will be turned OFF, the red
LEDs will go dark, and the white LEDs will light.
Power-OFF muting operation
• At the - voltage rectifier circuit with a small time constant that consists of D654, D655, C661, R652, D656, C662 and R653,
negative voltage is discharged for approx. 15 ms when the unit is turned OFF, Q556 is turned ON, and C553 is discharged in
the route of R562. Then the input relay (Q556) to which the differential amplifier is directly connected is first released.
Then the output relay is released slightly after the input relay when the electric potential at R562 has decreased.
• The current to be fed to the red LEDs is absorbed at Q566 and the red LEDs go dark approximately at the same time as the
www
input relay is turned off.
.
6. SERVICE MODE
There is no information to be shown in this chapter.
5
http://www.xiaoyu163.com
6
x
ao
u163
y
i
6
http://www.xiaoyu163.com
7
2 9
8
Q Q
3
6 7
1 3
1 5
co
.
TAD-M600
7
8
9 4
2 8
0 5
8
2 9
9 4
2 8
m
8
9 9
A
B
C
9 9
D
E
F
19
Advertisement
Table of Contents
