TNY 280 PN Trouble Shooting

[sabu31]

Hi All,

I am making an power supply based on TNY 280 PN. I got the design from Power Integrations designer suite. There is no 15 V output generated. How do I start troubleshooting the circuit (whats to be check in priority). The circuit and transformer schematic is attached. I have made pin 8 of the transformer as common point (RTN).

 

[cupoftea]

I woudl start like this.
Always use a diff probe if scoping, due to mains.

Check mains is connected.
Check all circuit conneections.
Do you have voltage on pri bus cap.
Do you have voltage on BP pin of TNY chip
Is it switching at all...is drain voltage goign up and down.
check r4 and r3 soldered in properly

 

[cupoftea]

BTW, are you using ultra fast diodes at secondary and RCD clamp?
You want trr = 75ns maximum...pref less.

Power integrations website also has troubleshooting guides for their flybacks

If you are like me, it is something silly, like mains not switched on....be wary of electrocuting yourself on the charged up capacitors when the thing is actually off...ive had hundreds of mains voltage electric shocks...the only one that hurt, was after i injured my arm, and then zapped myself on a cap that had 330Vdc on it......the electrocution impacted the exact part of my arm where the injury was....goodness knows how that happened....maybe because the injured part was full of conductive tissue fluid.

Otherwise, if you get back, we can get in to details of how you can check out your transformer is correctly phased, etc

 

[Easy peasy]

usually the Tx is made wrong of connected wrongly - dot notation ...!

also it is easy to make a constructional mistake elsewhere ....

 

[sabu31]

Thanks all. The issue was due to faulty IC. after replacing it . The system was working fine.