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Old 7th June 2009, 11:54 PM   #1111
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Default My MAGIC !

here it is my LM3886 GC,
it was made following a free project created and posted by an expert DIYer on the italian T-Forum..

hi-res internal connections :
Click the image to open in full size. Click the image to open in full size.

low-res external pics ( i love recycling used and ugly cases ) :
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details on the safety-earth star, completely connected to every external metallic part of the case (also the power switch case) but TOTALLY DISCONNECTED from the electric ground star (0v) because of ground loop noisy issues (or something similar )
Click the image to open in full size. Click the image to open in full size.
can you see any electric SAFETY issue ?
thanks,
marco
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Old 8th June 2009, 08:57 AM   #1112
Ted205 is offline Ted205  United Kingdom
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is the star ground floating ?
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Old 8th June 2009, 02:10 PM   #1113
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Quote:
Originally posted by Ted205
is the star ground floating ?
Hi Ted,
sorry for my poor comprehension (both in english than in tech.issues)
what do you mean with "floating" ?

the ground star connects the grounds from the two P.S. boards, the grounds from the two amp.boards, and the ground coming from the inputs and the outputs tied together, nothing more,
in this way it's floating form the safety earth
(in my last pics, ground star is above the safety-earth star, because they started to be connected, but i experienced the noisy issues, resolved by separating earths from grounds..)

p.s. i will soon try to reconnect them, because i've a new suspect for the cause of the noisy issue (a TV set, connected by SCART cable to my dvx player, which is connected by a passive pre-amp to this amp)

thank you
marco
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Old 8th June 2009, 02:10 PM   #1114
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sorry for the new post, i'm under moderation (new user) and i can't modify the above post..
i know that it would be better to connect grounds with safety earth by using one (better two) groud loop breakers (i've read this thread )
My need is knowing if my present configuration can be dangerous.. remember that my safety-earth-star connects every external metallic part to the earth pin of the IEC device, in which i connect line, neutral and earth coming from the wall plug..
tnx!
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Old 8th June 2009, 04:12 PM   #1115
AndrewT is online now AndrewT  Scotland
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Location: Scottish Borders
Quote:
Originally posted by madqwerty

My need is knowing if my present configuration can be dangerous.. remember that my safety-earth-star connects every external metallic part to the earth pin of the IEC device, in which i connect line, neutral and earth coming from the wall plug..
all exposed conductive parts must be permanently connected to Safety Earth.

This includes the far end of the speaker cables and the far end of the interconnects.

From your description it appears your chassis is connected to Safety Earth, but that the speaker return lead and input socket ground connections are only connected to the Audio Ground.

This is potentially very dangerous.
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regards Andrew T.
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Old 8th June 2009, 08:12 PM   #1116
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thanks Andrew..
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Old 14th June 2009, 10:02 PM   #1117
CECCO is offline CECCO  Italy
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Here's my new creation.
ciao.
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Old 14th June 2009, 10:03 PM   #1118
CECCO is offline CECCO  Italy
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Front
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Old 14th June 2009, 10:04 PM   #1119
CECCO is offline CECCO  Italy
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overview
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Old 14th June 2009, 10:05 PM   #1120
CECCO is offline CECCO  Italy
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