Grounding the Filament Winding

[alexmoose]

Hi everybody, I am getting buzzed from my amp, and I have to clue why, again and again I check, and double check to see that in truth everything is grounded, however everytime i try it i get a shock, so I am starting to wonder if it is not the Filament windind not being grounded. I have a hammond transformer that reads as follows

On green winding, which one do I put to the ground? any help is greatly apreciated

[SY]

If none of the cathodes in your amp are at high potential, then you can ground the heater CTs.

But if you're getting zapped, it's far more likely that you have a bad earth (safety) ground connection somewhere in your system. That requires immediate attention.

[jeff mai]

And start using your multimeter to check, not your finger!

[alexmoose]

Originally posted by jeff mai
And start using your multimeter to check, not your finger!

It worked countless times before I buzzed myself, so the first time it got me it was a surprise. but the first time it happend was right after I re-connected a heater, so I thought maybe there as something wrong there.

I am checking countless times with my Multimeter to see if my ground is good, and everywhere I have checked it is good but if seems like thats the problem, I will keep looking untill I find something

[Merlinb]

You haven't plugged the mains into a different wall socket to the one you usually use, have you?

[cogsncogs]

however everytime i try it i get a shock

Hi alexmoose, a lot of questions to follow. Just trying to cover all the bases.

When you say you get a shock, what are you touching? The chassis, ground, filament wiring connections? What about your primary connections? Are you sure that neither side of the primary is connected to your chassis ground? Which Hammond transformer are you using? Are you using a 2 or 3 wire power cord? How are your connections to mains (wall) supply?

On green winding, which one do I put to the ground?

Green/Yellow.

Wayne

[alexmoose]

Originally posted by Merlinb
You haven't plugged the mains into a different wall socket to the one you usually use, have you?

It's the same Wall socket, but it might be a different socket on the power strip

Originally posted by cogsncogs


Hi alexmoose, a lot of questions to follow. Just trying to cover all the bases.

When you say you get a shock, what are you touching? The chassis, ground, filament wiring connections? What about your primary connections? Are you sure that neither side of the primary is connected to your chassis ground? Which Hammond transformer are you using? Are you using a 2 or 3 wire power cord? How are your connections to mains (wall) supply?



Green/Yellow.

Wayne

I get shocked when touching the volume nob, and once I got shocked touching the minijack connect to the two RCA jack inputs, but that doesn't mean I couldn't be getting shocked on the whole Chassis, I suspect that I would be


I am using a 272HX 300-0-300v 200ma 6.3v winding CT 6a, and 5v CT 3? a the the 5v winding is doing nothing however, and is securly insulated

3 Wire, with the third wire grounded to the chassis

what do you mean Primary? one of the taps HV on my Power Tranny? Its possible that one was shorting, but unlikely

How are my connections to the wall supply? Its going through I three-prong power strip, I KNOW that the Chassis is ground too, because I can measure the correct potential between the Plate and the water pipe (my houses ground (I know its against code now))

These are all great ideas, but I never had a problem before, now assuming that I don't want to use my finger, can I then measure a potential between the volume knob and the water pipe?

[SY]

Are your chassis, front and rear panels, and potentiometer bodies all firmly connected together?

[alexmoose]

Originally posted by SY
Are your chassis, front and rear panels, and potentiometer bodies all firmly connected together?

I think so but I think I may have found the answer


see, I was cleaning the basement, and I disconected the right Channel, I then tested the amp apparently not remembering that it was disconnected and it got me, so is it possible that the right channel not being connected caused a potential to form between the case and the ground?

don't worry, the amp was only on for a few minutes (2-3) with no right channell

[kevinkr]

I think you might need to check that the ground connection on your power strip and the wall outlet are actually good. I would go get one of those outlet testers at home depot or rat shack.

Also use your multimeter and check to see whether you have continuity between the ground prong on your cord to all of the points you previously mentioned in your posts. You should measure well under an ohm taking into account the meter's probe resistance reading. (short probes together to find out, subtract this from total measurement.)

Nothing you have done would account for getting zapped in the way you describe. The other possibility particularly if you have AC or it is still cold and dry in your neck of the woods is esd discharge from you to your amplifier.

Be very careful however as this situation if due to a faulty ground connection could be quite hazardous, possibly fatal under the worst case scenario.

Also don't depend on other components to ground this one through the rca cables, interesting melting things have happened to such cables when fault current flowed through them to a properly grounded device.. Not a pleasant experience...

Be careful!