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No +5V for a switching mode power supply

sdancer75

May 2, 2017
5
Joined
May 2, 2017
Messages
5
A power supply (SMPS) outputs four dc voltages but one of them the +5 V have less than 2 V. The question is what component is responsible for the wrong output? What should I look for to fix the problem? Any recommendations ?

Voltage output : +5, +11, +19.8, +24

Current output : 0.15, 4.5, 0.5, 1.0A

Freq range : 50-60 Hz

Main components of the PCB

  • A1015 (LOW FREQUENCY AMPLIFIER)
  • C1815 (Audio Frequency Amplifier & High Frequency OSC)
  • HA17393 (Dual Comparator)
  • K2545 (DC−DC Converter)
  • FES8JT (Ultrafast Plastic Rectifier)
  • RS401L (BRIDGE RECTIFIER)
  • UC3842B-D (High Performance Current Mode Controllers)
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kellys_eye

Jun 25, 2010
6,514
Joined
Jun 25, 2010
Messages
6,514
Did you load the outputs prior to testing? Such PSUs usually require a minimum load in order for the regulation circuitry to kick in. Is there a separate regulator device for the 5V output? If so, it could just be a simple matter of replacement.
 

sdancer75

May 2, 2017
5
Joined
May 2, 2017
Messages
5
Did you load the outputs prior to testing? Such PSUs usually require a minimum load in order for the regulation circuitry to kick in. Is there a separate regulator device for the 5V output? If so, it could just be a simple matter of replacement.

Hi,

Yes, I load the output but one of them each time (not all simultaneously). I did see a seperate regulator 5V device.
 
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