messed up with SG3525 inverter

[jash2008]

Recently i built up a switch mode Ps with SG 3525 (Project 89). Till now i have puffed up about 25 Mosfets. every time i power it, the smps works well and the heating is also normal. But as soon as a 30 W load is connected at the output, the mosfet blows.

Can any body suggest the reason. I am using an ETD 39 Ferrite core with one 20# wire in secondary and two strands #20 wire in primary. the turn ratio is 4.0.

Thanks,

Gaurav Jain

[Perry Babin]

You should insert a 7.5 amp fuse in the B+ line. It should help save the FETs.

How many FETs are you using?

What is the part number of the FET?

What is the load you're using for testing?

Is it regulated?

If it's regulated and the rail capacitors can handle the maximum output voltage, set the voltage to the maximum possible with no load. Does it draw excessive current?

[djQUAN]

Originally posted by Perry Babin
You should insert a 7.5 amp fuse in the B+ line. It should help save the FETs.

How many FETs are you using?

What is the part number of the FET?

What is the load you're using for testing?

Is it regulated?

If it's regulated and the rail capacitors can handle the maximum output voltage, set the voltage to the maximum possible with no load. Does it draw excessive current?

He mentions it is based on ESP P89 so it is unregulated.

[I Am An Idiot]

Originally posted by djQUAN



He mentions it is based on ESP P89 so it is unregulated.

The ESP must stand for Extra Sensory Perception. I didn't see that part anywhere in the original post.

[Perry Babin]

http://sound.westhost.com/project89.htm

fig 2 shows a pot for voltage adjustment. He didn't say if he followed that schematic precisely or not. If he did, the pot would adjust the regulated voltage.