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Old 31st July 2012, 11:41 PM   #31
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To those of you who used a board (non-conducting chassis) as a test chassis, what did you do regarding PGND? Did you connect PGND to mains ground?

Thanks in advance.

Jac
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Old 1st August 2012, 01:42 AM   #32
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Quote:
Originally Posted by lehmanhill View Post
To those of you who used a board (non-conducting chassis) as a test chassis, what did you do regarding PGND? Did you connect PGND to mains ground?
Hi Jac,

like in the Evolution Rev A I've left PGND not connected.

In my case the amp sound worse with PGND connected to safety ground.

In this moment only transformers' shield is connected to safety ground; when it will be cased also the chassis will be connected to safety ground.

I'm pretty sure that grounding will be one of the more discussed topics in this thread...
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Old 1st August 2012, 09:05 AM   #33
bcmbob is offline bcmbob  United States
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The newer Antek toroids have a "shield" wire that I have connected to safety ground. It doesn't pass through to the amp. The older "standard" toroids and the ApexJr pieces don't have that feature. Just bought my first R-core for a DAC and it has a safety ground also - as noted above by Dario - again tied back to the AC inlet.

I see the shock hazard to be greatest from the power inlet to the trani. Good insulation and lots of heat shrink tubing can deal with that - IMO. The reduced AC voltages from trani to the amp I believe are less of a threat, but even that leg can be well protected from physical contact.

So I guess the two remaining issues are protection of some board components, and how safety ground effects the sound. Does that sound correct? I'm not sure if something like a CL-60 would be beneficial here. I have seen Siva recommend it's use on several threads.
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Old 1st August 2012, 09:10 AM   #34
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Bob!

Don't mention CL-60s!

You're risking AndrewT's blaming , if he's back from vacation...
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Old 1st August 2012, 09:30 AM   #35
bcmbob is offline bcmbob  United States
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Oops !

Well, I suspect it may have come up somewhere along the discussion. Have to see what develops.
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Old 1st August 2012, 01:44 PM   #36
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Default Boards up and running

I've finished my build, both boards are playing music in this moment

Click the image to open in full size.

I've had some trouble with one module though...

It power up correctly, relay was clicking but it was mute....

Guess what was the cause?

Click the image to open in full size.



An interesting demonstration

Click the image to open in full size.

As you can see, thanks to the new eagle object and positioning, there is clearance between board and heatsink.
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Old 1st August 2012, 03:38 PM   #37
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Dario, are you isolating the ic from the heatsink with anything but the thermal compound? It is hard to tell from the last pic.
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Old 1st August 2012, 03:39 PM   #38
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I was forgotting DC offset measurements:

6.4mV and 5.8mV

Quote:
Originally Posted by SoIL4x4 View Post
Dario, are you isolating the ic from the heatsink with anything but the thermal compound? It is hard to tell from the last pic.
Only thermal compound
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Old 1st August 2012, 03:55 PM   #39
bcmbob is offline bcmbob  United States
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Just to double check - did anyone buy the non-insulated LM3886? I don't know if they are even available new anymore, but could have been purchased on eBay. Those need an insulator. That is what is shown in the photo on post #29.
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Old 1st August 2012, 04:45 PM   #40
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Default Some addititional notes for builders

For those that bought the ERO kit

Solder the KP1834s as the last parts, after cleaning the boards.

Polystirene is very delicate and I can't find a datasheet to confirm or not they can stand with solvent washing.

Soldering temperature for C101/C201

The thermal pads of both caps need a very high temperature to be be well soldered, I would say around 370-380 C.

Final inspection before powering up

Before powering up inspect all solder joints surrounded by the groundplane to insure joints are exactly on pads without making bridges with the groundplane.

It shouldn't be a problem thanks to the soldermask but it's a cleaner and safer job.
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