Yesterday I had reason to use my signal generator, and while it was out, I took the opportunity to remove the two capacitors wired from the primary to chassis.

They were not at all what I expected in regards to looks, so I decided to post pictures of them for others. I had expected to see grey plastic covered axial capacitors like the ones commonly across the mains switch on the underside of turntables.

I would have replaced the caps with 2,000V ceramics, but the replacement mains lead with molded plug that I installed years ago does not have an earth.

Wayne.

I have made comment on those & a couple of their clones in the past. I do wonder how the hell they got into the country.

They may have been done that way for the US & European market where "Hot chassis" radio's common. The use of line caps to a chassis with no earth wire, was to actually provide a signal path for the antenna circuit (in radios) not so much for any filtering.

But as far as I am concerned, putting capacitors, line to chassis and to a device that has a metal case, is a dangerous practice.

Where the device has a transformer(and this does) , I fit a grounded (3 wire cable). If the caps are replaced they need to be a type "X" "X/Y" type approved for use on the mains (these are not supposed to fail shorted)

These " approved" caps will invariably be marked 275VAC (not a DC voltage) (The ones I got from RS are 300VAC) and they will be stamped with a variety of international Standards Association stamps.

There may also be oil filled caps in that thing. I have serviced two recently and have one with new valves surplus to requirements. Oil filled caps are often no better than Waxed Paper and these oil's were finished & replaced. It would be advisable to check yours.

Most devices will work without them. I have mains with a lot of RF floating on it and is prone to lightning surges. As a consequence filtering & surge protection is permanently on the lines.

I am disappointed that NBN had not realised this when they made their tower the highest object in a lightning prone area. So far in two major lightning events there have been problems. I see no evidence of any lightning umbrella?

Back in the olden days it was thought that 500V would be enough for power line (mains) work, as 250V times 1.4 = 352V peak. But lots of transient spikes ride on the line (mains). Experience teaches us in the USA that you need 1.4KVDC to avoid breakdowns.

It has gotten to the point here, where in several places, the computers & TV being two where I have MOV's permanently on the lines. Also caps as there is a lot of RF from the 24KV aerials.

What is scary is that I came home recently to find that two of them had actually activated & killed their circuits, as they were designed to do. It takes 30mA to trip the earth leakage protection and it had tripped on their circuits, so it must have been a decent transient.

I bought some caps recently & they are 300VAC, have not chased up their DC rating.

I did service a Japanese radio with 400VDC metal clad, oil filled types on the lines. I was really not shocked to find the contents of those caps, missing.

Marc