Power supply not working properly.
I have built a power supply using Engineering Prototype Report for EP-33 45W LCD Monitor External Power Supply using TOP247Y (TOPSwitch-GX). Initially it worked perfectly. But after some days the o/p dropped to 4V that too varying. (Thats all I can see on my multimeter). Kindly suggest what could be the problem.
Comments
This is a perennial problem. Out of 5 units that I assemble 3 have this problem. Hence I want to get to the root of this problem. I tried the following:
1) The problem seems to be on the primary side (since even on shorting the o/p the o/p simply oscillates between 12V & 0V but not like this).
2) I replaced all active components but in vain.
2) How do I check for a leaky cap. or do I replace all caps. just like that.
3) The mains transformer looks good. (No visible cracks seen even under a magnifying lens). Hence could the secondary coil (3.3uH) create this problem.
Kindly help.
This is a perennial problem. Out of 5 units that I assemble 3 have this problem. Hence I want to get to the root of this problem. I tried the following:
1) The problem seems to be on the primary side (since even on shorting the o/p the o/p simply oscillates between 12V & 0V but not like this).
2) I replaced all active components but in vain.
2) How do I check for a leaky cap. or do I replace all caps. just like that.
3) The mains transformer looks good. (No visible cracks seen even under a magnifying lens). Hence could the secondary coil (3.3uH) create this problem.
Kindly help.
Dear Shrikantbj.
I think problem may be with tarsnformer I assume your 2 PSu are functioning correctely.
1)Measuer Primary Indcutance.
2)Verifay the Start of secondary winding is connected to Anode of rectifer ( means winding termination is done correctely or not)
But this power supply that has conked off was working earlier. I have run a stepper motor on it. So transformer winding should not be an issue. While yes the core may be. But here also I do not see any visible damage to the core even under a magnifying lens.
Hello shrikantbj,
There are three points you have to verify. One possible reason for your problem could be the transformer, check for broken ferrite core. Another point to check is for bad electrolytic capacitors, check if any of them is leaking electrolyte or is mounted with wrong polarity. And finally, look for bad PCB solder joints.
Cheers,
PI_Crusher