sunfire signature has no earth/ground?

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surdo
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Re: sunfire signature has no earth/ground?

Post by surdo » Tue Mar 04, 2014 3:51 am

Thanks Bob P and others for your observations. OK, I need to find a technician locally. It's interesting with that Italian style plug in the photo above (with all pins arranged in a straight line), there would be no way of telling the neutral from the active line anyway and they'd be mixed up around 50% of the time when plugged in. Earthed plugs in Brazil at least have the earth pin offset so that shouldn't be a problem (unless the wiring in wall socket is inverted). The unearthed sockets in this apartment however allow for the plug to be inserted either way around. This isn't the case where I am from (Australia), where the pins on plugs and sockets are angled and can only be coupled in one orientation, but I thought in America, unearthed plugs are also invertible with 2 flat-bladed pins running parallel to one another. I'm probably misunderstanding something, but it's something that has made me curious since I read that with AC lines, the current only varies on the active line.

When I have an earth wire added, this should be screwed in anywhere on the chassis?

Thanks again!

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radioeng2
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Re: sunfire signature has no earth/ground?

Post by radioeng2 » Tue Mar 04, 2014 8:33 am

If I'm not mistaken, the fuse body is wired backwards too.

That makes it so if you go to check a fuse (like if you think you've blown it) and pull the cap off, the last contact as you remove it being the hot one in this case, you run risk of shocking yourself.

Safety dictates the back of the fuse holder body should be where the hot comes in and after passing through the fuse, leaves on the side contact.

Mark
I was there "At the Fest!" Hope you were too!

surdo
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Re: sunfire signature has no earth/ground?

Post by surdo » Tue Mar 04, 2014 9:17 am

Thanks Mark - yes it looks like you're right. Here is a clearer photo with some labels:
fuse_power.jpg
So, the correct wiring should be the following:

The black wire from the power cord should connect to B. A short piece of black wire should run from A to C. The white wire from the power lead should connect to D.

Is this correct?

Cheers,

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radioeng2
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Re: sunfire signature has no earth/ground?

Post by radioeng2 » Tue Mar 04, 2014 2:08 pm

surdo wrote: So, the correct wiring should be the following:

The black wire from the power cord should connect to B. A short piece of black wire should run from A to C. The white wire from the power lead should connect to D.

Is this correct?

Cheers,
Correct Surdo!


Guys, the incoming power stuff is simply nothing to mess up! You don't want to one day get behind your rig looking for why it sounds funny and be holding an interconnect in your hand and touch something else and have 120/220 at up to the breaker potential passing through from your hand to somewhere else on your body. It'll mess up your day! ](*,)

And what if you've still got the needle in the groove? Who'll shut it off....it might ruin your stylus. The EMT pounding on your chest might not worry about your prize vinyl either.

For decades now, when I find equipment made with a 3 prong plug that some nitwits pulled off the ground pin, the first thing I do is cut the end off and redo it with proper grounded plug. If something else is wrong, so be it and then you fix that. Safety first, music second.

I'll never forget seeing a DIY tube amp, with in excess of a 1000V B+, that for a chassis had 2X4's on each edge only, no bottom at all. It was on one of those cheap silvered wire metal "racks" from a hardware store. I had visions of a terminal or solder point underneath touching that rack. And then the guys wife vacuuming the floor, metal vacuum handle in had backing into the rack with her hip..... :-({|= But...but, the amp sounded good up until that point..... ](*,)

Good catch by Bob P.

Mark
I was there "At the Fest!" Hope you were too!

surdo
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Re: sunfire signature has no earth/ground?

Post by surdo » Tue Mar 04, 2014 2:36 pm

Just one last question about an earth. An earth wire can be connected anywhere on the interior of the chassis? Eg. There seems to be a screw located between C and D in the above photo that might serve as fixing point. There's absolutely no risk in adding an earth to this amp?

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jjptkd
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Re: sunfire signature has no earth/ground?

Post by jjptkd » Tue Mar 04, 2014 5:15 pm

I am not a tech by any stretch of the imagination but I have had well over 100 Sunfire amps, preamps and receivers pass through my hands and I have never seen one with a ground. Bill Flannery is an expert (and certified) Sunfire repair tech, you might want to give him a call. 425 232 9560

http://www.flannerysvintageaudio.com/
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radioeng2
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Re: sunfire signature has no earth/ground?

Post by radioeng2 » Tue Mar 04, 2014 5:38 pm

But this one has been messed with....some things must be done.

To answer the question regarding where to tag the line ground...it's supposed to be by itself, should be close to the cable entry normally, and it should use a tooth washer to dig into the metal and to keep it tight.

The only "risk" is if you wind up with ground loops. That can occur if you present different grounds to the equipment, different potential, and current flow results. With unbalanced interconnects, that's more likely to occur than with balanced.

I'd ten times rather fuss with grounding than have any possible way to have a hot chassis.

Maybe somebody else can explain some of the grounding in a different, and better, way than I can.

Mark
I was there "At the Fest!" Hope you were too!

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fill35U
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Re: sunfire signature has no earth/ground?

Post by fill35U » Tue Mar 04, 2014 7:08 pm

surdo wrote:And to answer fill35U's question: the amp is plugged into a surge-guard and this is plugged into 220v, 60Hz mains outlet. As I mentioned earlier the outlets in this apartment are not earthed, unfortunately, that's the situation, but I am moving shortly to another property where I can ensure the sockets are earthed.

From the photos above, to me at least, the power supply does not seem to be modified and lacks an earth.
Now I'm not a smart guy- in fact, likely the opposite. But I think a little more info would be useful:

Surdo's dwelling has no earthed outlets. How is he going to ground *anything*? Sure, he could run a wire to a water pipe. But it's a rental apartment- how does he verify the integrity of the pipe to ground? Does he drive his own ground rod? Tie in to structural rebar for an "Ufer"? Lay out a huge counterpoise? ;)

Where does he stop? Does he bond just the Sunfire to ground? Set up a bus and run wires to all of his equipment and appliances, even the portable ones, that aren't double-insulated?

Might as well call an electrician, and have earthed wiring and receptacles installed- if his landlord will let him.

I don't know much about power distribution, even less about how it's done in Brazil, and not the foggiest about how Surdo's apartment is actually wired. But is it possible that his 220V is derived from a center-grounded Y (220/400V), or even a corner-grounded delta? Is one conductor of his 220V a neutral?

I wholeheartedly agree that the chassis should be connected to earth *somehow*, either via a separate ground conductor, or the neutral by a polarized plug. Any chance there's an impedance grounding network between a neutral conductor and the chassis in that thing (caps, diodes, resistor?). Hopefully enough to trip a protective device...

Edit: There's always GFCI's...

Just my random thoughts, thank you all for indulging me...
Last edited by fill35U on Tue Mar 04, 2014 9:25 pm, edited 1 time in total.
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radioeng2
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Re: sunfire signature has no earth/ground?

Post by radioeng2 » Tue Mar 04, 2014 7:48 pm

Well....for a not smart guy, you ask some good questions.

From here, it's tough to do more than guess at answers. I suppose with a VOM and a little investigation, some answers could be found. Generally, a ground of some sort should be able to be figured out. The box could even be grounded (sort of) like was typical here before things went to 3 wire.

Being short term, I'd make the amp right, get something for a ground and at least head to a more permanent location with the beginnings of something proper.

Mark
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Magnaryder
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Re: sunfire signature has no earth/ground?

Post by Magnaryder » Tue Mar 04, 2014 8:17 pm

IIRC, surdo said his current dwelling has no grounded outlets but his new one does. Correct me surdo

ray
Magnaryder

Its going to be used equipment when I sell it, so it may as well be used equipment when I buy it.


surdo
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Re: sunfire signature has no earth/ground?

Post by surdo » Wed Mar 05, 2014 5:12 am

Yes that's more or less correct. We bought a place (a house) which is currently occupied. I didn't check the power supply there, but when we move in, I'll be in a position have an earth put in where necessary. The following link shows the new system in use in Brazil since 2009. If you scroll down the page to the second image, the socket on the right is the new system, the socket on the left will look familiar to you and was in use until the new system came in, in *some* installations (there was another type used for washing machines and air conditioners that looked like a 20a version of the the Australian system).

For the image below, Earth/ground = terra, active/hot = fase, neutral = neutro.

http://www.intelpremierprovider.com.br/ ... _9184.html

Cheers

surdo
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Re: sunfire signature has no earth/ground?

Post by surdo » Wed Mar 05, 2014 4:24 pm

Following jjptkd's suggestion I called Bill Flannery today and he kindly gave his opinion. Bill agreed that the active wire must connect to the fuse and was also disturbed that the earth-less plugs we're using here offer no polarity (can be plugged in both ways). He said he wouldn't even plug the amp into wall under those circumstances. He was less concerned about the earth and said it would have to be my decision to add an earth as it would constitute a modification of the amp. He also stressed that he is not an electrician. Interestingly he said that in audio systems it's common practice to have only one piece of equipment earthed and that this is often the power amp.

So this afternoon I went to a technical place and asked them to remove the power cable and replace it with another. I chose a 20a version of the current Brazilian standard (which has an earth), not sure if that is an overkill and I will need to replace the wall socket in this new house to accommodate the thicker-pinned plug (and for the moment I have to use an adapter). The technician rewired the amp correctly (as described in the posts above) and in the end, I decided to have the chassis connected to the earth wire. I also bought one of those test screwdrivers to determine the active line on my power outlet at home. Have labelled everything with a marking pen and have connected and tested the amp - it's all running fine.

I hope the problem is now resolved! And I'd like to thank everyone for their contributions in this long thread. I've learned quite a bit too along the way and I'm sure the amp is in a much safer state. Cheers,

angelod307
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Re: sunfire signature has no earth/ground?

Post by angelod307 » Wed Mar 05, 2014 4:44 pm

Well done, now for the photos to ohhh an awww over please...
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surdo
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Re: sunfire signature has no earth/ground?

Post by surdo » Thu Mar 06, 2014 6:22 am

OK, why not....

Brown = active, blue = neutral, green/yellow = earth
earthed.JPG
20a.JPG

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jjptkd
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Re: sunfire signature has no earth/ground?

Post by jjptkd » Thu Mar 06, 2014 9:09 am

Looks great, glad you got it all worked out!! =D> =D>
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