Rated Voltage
Permissible Range
Working Current
Working Load
VCC
+ 4.75V ~ 5.45V
17mA
Front board and muting circuit
+ 5V
4.75V ~ 5.45V
520mA
Loader servo, motor driver, laser circuit,
audio D/A and T F circuit
+ 3.3V
3.20V ~ 3.46V
650mA
Decoder board
VA+
VA-
+8V +/-10%
-8V +/-10%
15mA
15mA
Audio & Karaoke circuit
Audio & Karaoke circuit
-24V
-20V ~ -25V
10mA
Bias voltage of VFD on front board
Filament of VFD on front board
AC1-AC2
AC 2.8V ~ AC 3.5V
80mA
4
b. Troubleshooting and service
1. Troubleshooting and Service of Power Supply
a. Principle of power supply operating
Adopts switched-mode power supply module TOP233Y of TOPSWITCH company, it can protect
itself from over current, overheating, and short-circuit, etc. This circuitry mainly stabilizes at +5V,
and fluctuates within a permissible range, such as +5V, VA+, VA-, +3.3V and -24V. Please pay
attention to the high voltage inside the white paint of PCB while repairing. When using an oscillator
to measure this portion, an isolated transformer must be connected.
Circuit of power supply may output the following power sources:
a). If +5V voltage varies out of the permissible range, check whether sampling resistance R8 and
R9 (R422 and R423) are eroded, and whether the 1st pin of regulated voltage reference U3 (U402)
TL431 is at 2.5V. If the deviation is over 0.1V, TL431 is eroded and shall be replaced. During
maintenance, the +5V sampling circuit, i.e. D9, R5, R8, R9 and U4 (D415, R419, R422, R423, R421
and U403), shall not be open, otherwise, it may result in high voltage and damage other circuits on
the rear pole.
b). If all the output voltage is 0V, and a voltage of 300V or so exists at the positive pole of C8 (C403),
check w5V, +8V, -8V, -24V and +3.3V are short (whether Q401, Q402 and Q403 are open).
c). If +3.3V of AC1-AC2 is 0V and no display on VFD, check whether D6 (D408) is open. If the ribb
on wire is not in good contact, replace the corresponding ribbon wire.
Note: Components in the brackets are of TDE-F70/F71.
2. Troubleshooting and Service of the Loader
a. No running of loader
a). Check whether the 24P ribbon wire to loader is in good contact.
