DUS 60 Digital Ultrasonic Diagnostic Imaging System Service Manual
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Trouble fixation and correction:
Switch down the system before checking the PCB. Check mutual inductance filter by multimeter
to make sure there is no open circuit. Check the bridge rectification circuit in the four bridge
channels to examine if shortness or open circuit exists in each channel, by diode function on
multimeter. Check short circuit in every output current by multimeter. Do not use the oscillograph
to check.
● Fuse burn out as the device is switched on
A、Check anti-jamming capacitance and thermal resistance.
B、Check short circuit in commutating current, and check filter capacitance 220UF/400V.
C、Check switching transistor NCP1337.
D、Check short circuit in switch transformer.
● No output voltage
A、Check the voltage of collecting anode in switching transistor NCP1337. If the voltage is 0, that
is to say the AC input current or commutating current is open circuit
B、If the voltage of collecting anode in switching transistor NCP1337 is around 300V，the reason
may be the switch oscillating circuit stop oscillating caused for the reason that the start up circuit
is open, interior switching transistor is open circuit or positive feedback circuit is open.
C、Rectification output load is short (Schottky arcing)
● Output voltage is low or high
A、Stabilivolt element in switch power supply is not qualified.
B、5V voltage is low or high.
C、Output stage has short circuit，and load current is too large.
Mainboard
To verify the mainboard,
1. Open the main unit using the procedures described in section 5.3.
2. Switch on the monitor.
3. Use a multimeter to measure the voltage to earth of the pins list below.
Test point Reference result Test point Reference result
T2 A3V3 HV T21 D1.8V
T3 D2.5V TP1 D2.5V_DCDC
T5 D1.2V TP2 A5V
T7 TGC: 963 mV ~ 3550 mV TP3 D5V
T9 A3V3_VCA TP5 A-40V
T13 VDDMCU_1V2 TP15 A3V3_HV
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