View single post by markcm
 Posted: Sun Jan 22nd, 2006 08:50 pm
PM Quote Reply Full Topic
markcm

 

Joined: Sun Jan 22nd, 2006
Location:  
Posts: 10
Status: 
Offline
I have just researched the TNY255P 8pin IC located at the source of my mystery noise and it is a switching device commonly used for stand by modes in electronics. As my noise changes from Standby to ON, this may be narrowing in on the cause of my audible noise. I have attached a diagram equivalent to the circled area of the picture I posted in my first post.

The 817b looks to be an optical isolator used in conjunction with the switching tny255p, I don't suspect it is the cause.

Here is the .PDF to the TNY255P IC

http://www.powerint.com/PDFFiles/tny253-255.pdf

This .PDF clearly describes the operation of this chip with the capacitors and the transformer also discussing audible noise if the circuit is not tuned properly with the transformer or capacitors. I a reading more now, if you have ideas this document seems like a very likely source for resolution to my issue.

My next plan is to test/ replace the components associated with this TNY255p switch circuit.

Attachment: (Downloaded times)