power supply not working ? Direct 52 Vdc output not regulating ......

power supply not working ? Direct 52 Vdc output not regulating ......

Having components :

L7812CV (Regulator)
L7805CV (Regulator)
E3055 (Transistor)
2 pieces of 2N3055 (power transistors)

No physical burning of any component , what component might gone bad ??

http://www.lightinthebox.com/Zhaoxi...y-For-Lab-PS-305D-H290408011750-_p106486.html

**broken link removed**

Product Name: ZHAOXIN RXN-605D Power Supply
Product Description:
Brand：ZHAOXIN

Model：RXN-605D

Origin：Shenzhen
Weight: 6KG



2 Digital Meter Display

■ Constant Voltage and Constant Current
■ High Effeciency,Small , Light Weight
■ High Power Density
■ Protective Function for Over-load and reverse polarity



Model RXN—602D RXN—603D RXN—605D

0-60V/2A 0-60V/3A 0-60V/5A

Constant Voltage Characteristics：

Voltage Regulation CV ≤0.01%+2mV ≤0.01%+2mV ≤0.01%+2mV

Loading Regulation CV ≤0.01%+2mV ≤0.01%+2mV ≤0.01%+2mV

Ripple and Noise CV ≤1mV（effective value） ≤1mV（effective value） ≤1mV（effective value）

Voltage Temperature Coefficient 150ppm/℃

Constant Current Characteristics：

Current Regulation CC≤0.2%+2mA

Load Regulation CC≤0.2%+5mA

Curent Temperature Coefficient 500ppm/℃

Ripple and Nouse CV ≤2mV(effective value)

Indicating Accuracy：

Disply： Digital Display Digital Display Digital Display

thanks

You should check output transistors first.

the power transistors (2N3055) ??? should test them first

i found it , one of the 2 power transistors gone bad ...... i checked it , tested it & replaced

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by the way , which type of power supply is this ?

Constant current ?? , constant voltage ??? switch mode ????

The transistor that was bad has :

Base to Emitter Resistance : 155.6 ohms (for both forward bias & for reverse bias also)

Base to Collector : 168 ohms (for both forward bias & for reverse bias also)

Collector to Emitter : 14 ohms (for both forward bias & for reverse bias also)

I want to ask whether this transistor shorted or its become open , what problem it got ?

thanks

if your voltage 52V goes directly to your power supply output ..... its mean transistor has shortage if its will be open than you should have output voltage = 0
"open" usually means no connection in electronics.

by the way , which type of power supply is this ?

Constant current ?? , constant voltage ??? switch mode ????

Click to expand...

This is a regulated voltage and constant current power supply as per the specification of the product. And as per the Product weight specified it seems to be containing a Transformer inside and not a Switching PS.