SMPS Transformer noise and Low output voltage

Thread Starter

SMPS Lover

Joined Apr 9, 2021
19
As replacing the TL494 has fixed the problem we no longer need to trace out the schematic of your power supply. The idea was to create a schematic so we could understand exactly how it was designed to work and from that work out which parts of the circuit may cause the symptoms you describe. From that stage we could suggest tests for you to do to prove or disprove any theories.
This is normal faultfinding practice to identify the part that is causing the fault and replace it. You are lucky that you guessed which component was the cause. The most common fault with switch mode power supplies is a component failing short circuit and causing other components to fail. With that sort of fault you have to be sure that you identify all of the failed components as missing one very often causes all the replaced components to fail again when powered back on.

Les
Well noted, Les, i want also to thank you so much for your help and coaching to understand what happened.

Hope to talk to you soon around other challenges.

Best Regards
 
These are so called primary side regulated .its a routine case in constant current PSU s.depends on the primary current ,the output voltage is estimates,though with less accuracy
 
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