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Alien DAC v1.1 Construction Thread - Page 14

post #196 of 1560
8/12/06 at 8:12pm
Question on a power source. I've got a 6v AC-AC wall wart sitting around the spare parts bin. I've got an onboard fixed 5v regulator on the dac. Could I just chop the tread schematic off at the LM317 and use the diode bridge and filter cap portion? From the tread part description it seems like that is responsible for the AC-DC conversion. And since I'm only regulating 6v to 5v, I don't think I need to use the lm317 to drop a half volt so there is still enough for the reg101-5 to work right.

Quote:
If you choose the AC-DC type of wall wart, there are a few additional advantages over the AC-AC type:

* You can leave the diode bridge and filter cap out when building the TREAD.
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post #197 of 1560
8/12/06 at 9:28pm
That will work pddjsteve (Assuming its physically possible to do that to a TREAD board) although one thing you have to take into account is that you might actually have more than 6v after the diode bridge. You can not feed the reg101's more than 10v.

Rob.
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post #198 of 1560
8/12/06 at 9:39pm
Quote:
Originally Posted by robzy
That will work pddjsteve (Assuming its physically possible to do that to a TREAD board) although one thing you have to take into account is that you might actually have more than 6v after the diode bridge. You can not feed the reg101's more than 10v.

Rob.

Hmm. Yeah, I'm aware of the limits of the reg101. I wasn't meaning actually chop off the tread board, it was more a figurative chop off. I was going to try to do it on some protoboard. I hadn't thought of the dc being higher after the diode bridge though. So I might be better off just going with a full tread and setting the lm317 for something like 5.5v output anyways?
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post #199 of 1560
8/14/06 at 10:28pm
Another Alien DAC is alive!!
First time doing smd, the PCM2702E gave me a little bit of trouble, but not too bad, took only 5min or so, after that, everything was easy.

Went with the regulated usb option regulated to 4.81v, outputting to an a47 i just finished yesterday, sounds great! pics to follow soon.

btw, how would one case this in the hammond case? the usb connector doesnt have anything to attach to the front panel......
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post #200 of 1560
8/14/06 at 10:42pm
Quote:
btw, how would one case this in the hammond case? the usb connector doesnt have anything to attach to the front panel......

See the chunk of sheet stock with the foam stuck on it?

The foam is there so I can remove the trim bezels without having to cut a new piece of filler.
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post #201 of 1560
8/14/06 at 10:51pm
Quote:
Originally Posted by MisterX

See the chunk of sheet stock with the foam stuck on it?

The foam is there so I can remove the trim bezels without having to cut a new piece of filler.
MisterX, could you elaborate? Maybe I'm just brain-dead tonight, but I'm having trouble visualizing this. I would've thought after cutting the USB opening, all you'd have to do is keep the DAC board from moving within the case when you plug in the USB cable.
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post #202 of 1560
8/14/06 at 10:52pm
Quote:
Originally Posted by tomb
I would've thought after cutting the USB opening, all you'd have to do is keep the DAC board from moving within the case when you plug in the USB cable.
errr.... let me rephrase.

That is exactly what the chunk of metal does.
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post #203 of 1560
8/14/06 at 11:18pm
MisterX, how did you cut that nice neat square hole? I've been pondering how I'm going to take on that job.
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post #204 of 1560
8/14/06 at 11:19pm
So..... tell me if I understood how your contraption works

the piece of metal with the foam on will go in on one of the slots in the case, and is sized so that the foam pushes against the back of the usb receptor when both side of the bezel is shut, correct?

btw, howd you cut your square hole? dremel? looks very very clean

[Edit] gah NeilR, you beat me in asking about the square hole!
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post #205 of 1560
8/14/06 at 11:43pm
Quote:
Originally Posted by Fiola
So..... tell me if I understood how your contraption works

the piece of metal with the foam on will go in on one of the slots in the case, and is sized so that the foam pushes against the back of the usb receptor when both side of the bezel is shut, correct?
That's kind've what I was thinking, although I was a little surprised to read that the "sheet stock" is metal. Ingeneous of MisterX, perhaps, because this supports the stresses of plugging/unplugging a USB cable at the connrctor. The simplistic solution would be to put a couple of stops next to the board's edges in the case slots, but this would allow stress on the USB solder connections on the board.

Quote:
btw, howd you cut your square hole? dremel? looks very very clean

[Edit] gah NeilR, you beat me in asking about the square hole!
A good scroll saw with the right blade and lubricant might work well. Anything else might not give a sharp edge at the hole's corners.
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post #206 of 1560
8/14/06 at 11:48pm
Quote:
Originally Posted by Fiola
the piece of metal with the foam on will go in on one of the slots in the case, and is sized so that the foam pushes against the back of the usb receptor when both side of the bezel is shut, correct?

You are almost there.....the chunk of metal fits between the slots in the case and "pushes against" the circuit board when the end plates are secured to the enclosure.

Maybe another picture will help?




Quote:
btw, howd you cut your square hole?
Drill a 3/8" hole, use a 1/8" rotary file in the dremel to get the hole close and finish it with a file.
Piece of cake that takes a great deal of patience.
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post #207 of 1560
8/14/06 at 11:58pm
OK, I guessed wrong. Looking at your first pic, I thought perhaps the sheet stock slid in upside down in one of the top slots, so that the foam was pressed up against the back of the USB connector - then wedged against the back plate.
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post #208 of 1560
8/15/06 at 12:04am
Quote:
Originally Posted by tomb
OK, I guessed wrong. Looking at your first pic, I thought perhaps the sheet stock slid in upside down in one of the top slots, so that the foam was pressed up against the back of the USB connector - then wedged against the back plate.

how do figure that would work with all of those capacitors in the way?
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post #209 of 1560
8/15/06 at 8:50am
Quote:
Originally Posted by MisterX
how do figure that would work with all of those capacitors in the way?
Good point - it would have to be a "fitted" piece of foam, and you'd have to insert the board and the backstop at the same time, with both in their mutual final position (assuming a longer piece of sheet stock). Most likely the USB solder tabs and the Hammond slots are more than enough to keep the joints/board from flexing.

I was just brainstorming ...
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post #210 of 1560
8/15/06 at 12:45pm
misterX your construction is perfect!!!
that is exactly what i want to do! the same RCAs and the same box!
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