Power supply does not work if bias winding voltage reduce

Hi,

42V is unusually high voltage for the bias winding. This voltage is higher than the rated operating voltage of most optocouplers that are typically used for feedback.

Generally a 15V bias winding is most appropriate for most designs.

Please send us a copy of your schematic to help us understand why your design needs such a high voltage on the bias winding.

Regards

PI-Sarek

Hi,
I have attached schematic of my supply for ur reference.
Actually we dont need 42V bias voltage but some how due to the transformer it goes to 42V. So i have replace 27V over voltage zener by 42V.
How can i drop the bias voltage?
I have discussed this problem with Xmer manufacturer so they made some changes in Xmer, reduce the bias winding turns.
But now my supply is not working with new Xmer. It oscillate ON-OFF.
It works fine with the older one.
Please suggest me some solution to this problem

Hi,
I have attached schematic of my supply for ur reference.
Actually we dont need 42V bias voltage but some how due to the transformer it goes to 42V. So i have replace 27V over voltage zener by 42V.
How can i drop the bias voltage?
I have discussed this problem with Xmer manufacturer so they made some changes in Xmer, reduce the bias winding turns.
But now my supply is not working with new Xmer. It oscillate ON-OFF.
It works fine with the older one.
Please suggest me some solution to this problem