AT 230W SMPS circuit diagram

[shamikrudra]

Hello
i have an 230W smps with out load it gives all the output but on load it colps after start if any one can give me the idea what is wrong in this PS.

 

[Nigel Goodwin]

Hello
i have an 230W smps with out load it gives all the output but on load it colps after start if any one can give me the idea what is wrong in this PS.

First thing to check! - all electrolytics for low ESR!. However, you should bear in mind that a PC power supply probably won't run without a load, and certainly won't run properly!.

 

[Sebi]

The +5V output always need serious load for proper work.(min.2...5A)
Sometimes cannot start with automotive (50..100W) bulbs, because the cold resistance too low.
As Nigel said, the capacitor's ESR test is a good idea, in my exprience the one year old PSU have 60..70% bad caps!

 

[ante]

A resistor 4R7 >10W works fine on 5Volts as a load for testing.

 

[shamikrudra]

Hello
i have an 230W smps with out load it gives all the output but on load it colps after start if any one can give me the idea what is wrong in this PS.

i have found transister 4242 blown i have replaced it, 330uf200V with 330uf250V only -12V is showing -10.56V and +12V is 11.8 is my TL494 working fine after chenging ? my PS is JNC make 230W AT type can i get circuit diagram of this PS?

 

[Sebi]

The measured values are good, all values depends from load, except the +5V. Here is a sematic, not exactly for Your PSU, but the solutions are same and give a good startpoint.