WOPL 700B A/C hum ?

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
6,955
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#23
Yes Sir,

the RCA's ground via a copper strip between and common to both ... Not directly to the chassis....
The drinking straw trick ??? That's new .... I can only assume insulating the bolts as they run the length of the
laminated stack ?

Matt
Yes and fiber washers under the head and nuts of the retaining bolt. The bolt has to be completely insulated from the transformer stack. It minimizes eddy current losses in the transformer stack and reduces the transformer idle current.
 

mattoe

New Around These Parts
Joined
Oct 2, 2016
Messages
34
Location
Hamilton Ont Canada
Tagline
Don't let any smoke out !
#24
Yes and fiber washers under the head and nuts of the retaining bolt. The bolt has to be completely insulated from the transformer stack. It minimizes eddy current losses in the transformer stack and reduces the transformer idle current.
Ok I can see that as plausible.... I will source out some hd fiber washers and will use some heavy wall shrink tubing on the bolts ....

Great thought Thank you !


When I get it back apart ..(again) I will post pics of the rca's and the connections to the "star " grond....
 

mattoe

New Around These Parts
Joined
Oct 2, 2016
Messages
34
Location
Hamilton Ont Canada
Tagline
Don't let any smoke out !
#27
Hey Guys,

I finally made it back to the 700 hum.... I removed the transformer bolts and put fiber washers at both ends , effectively isolating the bolts from the core... Poked around and put things back together..... No more hum.... Hard to say if the bolt washers did the trick or simply the act of disassembly and reassembly..... Cheers Thanks for the suggestions!

Matt
 

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
6,955
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#28
Glad to help Matt. I do that on mine...learned that fact a long time ago (mid-late seventies) when I was specifying transformers in a small engineering company.
 
Top