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Troubleshooting STR IC Regulator Power Supply

A. Unable to start.
Can be caused by:
  • No start-up voltage supply Vcc or a voltage less than 16V
  • Electrolityc Capacitors supply voltage Vcc filter dry.

2. Led indicator blinking
If the supply voltage Vcc examined rocking. This is because the regulator of life and death because OVLO work., Die-protectionist regulators and auto start life over and over. If it is turned off  Electrolityc Capacitors  usually still keep the rest of the cargo.
Can be caused by:

  • Electrolityc Capacitors supply voltage Vcc filter on a pin-4 dry. Replace with a value equal to or slightly larger. - triger UVLO
  • input filter capacitor on pin-1 feed dry behind the declining value - triger OLP
  • Rectifier diode of the switching transformer is damaged (sometimes when examined with avo-meter looks like a still good)
  • cause the supply voltage Vcc drops of the switching transformer (UVLO)
  • Part damage or broken lines on the feedback circuit of the voltage regulator through B to photocoupler - triger OVP
  • Electrolityc Capacitors dry filter voltage B - triger OVP
  • One of the output voltage of the switching transformer secondaries there is a short (over load) - triger OLP
  • Soft start capacitor value decreases - triger OLP

3. Noise arising (noise)
Can be caused by:

  • Transformer windings slack.
  • If there are ceramic capacitors - can sometimes cause interference noise due to its characteristic piezoelectrik like crystal resonator. Replace with film capacitors.

4. When the st-by normal stress. But when the power is on the regulator directly off protectionism no voltage on the secondary this part.  Electrolityc Capacitors  are still storing charge.
Can be caused by:

  • Sensor OVP small value resistor on pin-2 to the ground so that the value of delayed triger to OLP or OCP.
  • Regulator IC is damaged

Note: Be careful when the regulator is not working. Because of  Electrolityc Capacitors  may still have a charge when turned off.

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