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Old 26th September 2004, 01:03 PM   #1
Franz G is offline Franz G  Switzerland
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Default Security: even with gainclones an important issue!

As we (most) connect our gainclones to the mains, we should be very good informed about the professional security rules and norms.

At least, we should be aware of them. Some members from this forum are very knowledgeable in this topic, others, like me, are absolutely no professionals and have some personal opinions, what could be dangerous. I remarked already very valuable statements about security and norms from Upupa Epops, in this forum. Maybe, it is a good advice for amateurs like me, to read his statements (they will follow soon).

Here, I beginn with the main part: the primary connection of my experimental amp in the actual status (bad example, dangerous!!!).

Click the image to open in full size.

Must be a good start, to list the rules how to make a cabling like this safe.

For a long and secure life!
Franz

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Old 26th September 2004, 01:12 PM   #2
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Hi Franz

Good thread, we mods appreciate this kind of topic as useful and informative.

Can we change the title to "Gainclone Electrical Safety" or something similar though? That way it will be more informative for people searching the forum.
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Old 26th September 2004, 01:14 PM   #3
Franz G is offline Franz G  Switzerland
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Al

Yes, feel free to choose the best title for this topic. Why not change it to a permanent "top" topic?

It would be worth, for safety of every cloner, their families and future owners!

Beginners dont search for security, they have the head filled of other dreams! So, it would be very good to see not just valve amps have some security issues. Right in the top of this forum.

Franz
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Old 26th September 2004, 01:26 PM   #4
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While having no qualifications (Iím currently a young engineering student) to legally work with mains power in my country, I do so none the less

Now in your pic, if would have heat shrink tubing covering all the bare wires plus hot melt glue around where the solder tabs enter the plug where the tubing doesnít quite cover as Iíve once still been shocked by a switch where I managed to touch a tiny bit of the bare tab in there and it scares the life out of you (and literally if your unlucky)

So personally if itís all covered up with adequate insulation and wonít come off easily (and electrical tape usualy does, i'd only use it for temporary use) then its safe in my opinion
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Old 26th September 2004, 01:38 PM   #5
Franz G is offline Franz G  Switzerland
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The second topic in after primary/mains connection should be: the output side:

When and why should output connectors be isolated, so they cannot be touched?

Every reader would agree with me, it makes no sense to set a rule and then selling amps with removable isolation like this:

Click the image to open in full size.

A bad joke, isn't it? As you cannot use the amp, without removing them!

Franz
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Old 26th September 2004, 01:51 PM   #6
Franz G is offline Franz G  Switzerland
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And last, but not least, a very important part:

The central grounding of the box. Here my version:

Click the image to open in full size.

Franz
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Old 26th September 2004, 02:01 PM   #7
Nuuk is offline Nuuk  United Kingdom
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YES excellent thread Franz!

I'll add a topic if I may.

Some people have the PSU in a separate box/case/chassis. The argument then is that there is no need to earth/ground the amplifier case as there is only the rail voltages inside.

But I was once told that it is possible to still get a mains voltage into the amplifier case, one example being suggested was in the case of a short across the primary and secondary coils of the transformer.

So, could somebody knowledgeable on this either confirm or correct the above?
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Old 26th September 2004, 02:05 PM   #8
Magura is offline Magura  Denmark
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Any piece of equipment MUST be grounded, as a trafo going south or broken isolation will most surely bring mains to the entire system.

Magura
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Old 26th September 2004, 02:09 PM   #9
Franz G is offline Franz G  Switzerland
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Please, for security reasons, let the answers in this thread for really good informed people (maybe you are) but don't stop to ask safety questions here.

Statements like this are not what I want in this important thread:

Quote:
Any piece of equipment MUST be grounded, as a trafo going south or broken isolation will most surely bring mains to the entire system.
... as most of us are already knowing. Sorry!

Every answer in this thread should be from an expert, because it concerns safety.

Upupa Epops, for example, will be back in a few hours and then begin (sorry, when I cause you some work, Upupa ) I am quite sure, he will present us a basic list to start discussion.

Don't hurry, be safe! Lets build up this thread slowly, mainly with open questions, please.

Franz
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Old 26th September 2004, 02:17 PM   #10
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Nuuk

Anything that is not double insulated should be connected to mains ground. It is not mandatory for items with separate PSUs, at least in Europe, but devices that are made this way do have to pass certification to get the CE mark and be built in an electrically safe manner. As we, as diy'ers, don't have this independant checking system, then I would go for earthing everything on a matter of principle.

Franz

Excellent use of star washers and suchlike, but diyAudio regulars will tell you about my phobia of using solder joints for safety critical applications. Crimps rule in my book!

As for the output side, EU regulations state that you should not be able to come into contact with potential differences of more than 48V. With a standard audio amp this is easily possible across the output terminals.

The plugs in the ends of the binding posts are, I believe, to stop people from 110V countries pugging in mains plugs that have the same pin spacing. However, I could be wrong!
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