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Alien DAC v1.1 Construction Thread - Page 80

post #1186 of 1560
5/18/08 at 10:22pm
Quote:
Originally Posted by wiatrob View Post
I've just put together a Glass Jar kit, USB powered . I'm only getting about 1.23vdc from the 3V3. I get a rock solid 4.7vdc on the 5V.

Yes, it's my first surface mount with pitches like the 2702! I've checked my solder joints as well as I know how (they look good - to me - ) but is there something I'm missing?

Anyone know of anything specific I might check? Thanks all for any help!

-Bill

(I'm working on some pics of the board if it might be helpful.)
Double check the soldering on the 3.3V regulator and make sure it's oriented properly.
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post #1187 of 1560
5/19/08 at 12:06am
Quote:
Originally Posted by wiatrob View Post
I've just put together a Glass Jar kit, USB powered . I'm only getting about 1.23vdc from the 3V3. I get a rock solid 4.7vdc on the 5V.

Yes, it's my first surface mount with pitches like the 2702! I've checked my solder joints as well as I know how (they look good - to me - ) but is there something I'm missing?

Anyone know of anything specific I might check? Thanks all for any help!

-Bill

(I'm working on some pics of the board if it might be helpful.)
http://www.head-fi.org/forums/3890511-post1059.html

This effected the 5V instead of the 3.3V, but you need to check all the resistances around the regulator as well. And make sure they are actually grounded. These boards will allow you to do joints that look soldered OK, but aren't making good connection.
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post #1188 of 1560
5/19/08 at 10:36pm

Thanks for the tips.

Quote:
Originally Posted by Pars View Post
http://www.head-fi.org/forums/3890511-post1059.html

This effected the 5V instead of the 3.3V, but you need to check all the resistances around the regulator as well. And make sure they are actually grounded. These boards will allow you to do joints that look soldered OK, but aren't making good connection.

Thanks Par (and all), these are definitely avenues I'll check. I know REG101-33 is properly oriented, and I've verified all resistors are in their proper locations.

Off to search for that elusive cold joint!

-Bill
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post #1189 of 1560
5/19/08 at 11:05pm
Turns out it was a bridged C22, now getting a solid 3.29V and the computer recognizes the DAC. Thanks again.

-Bill
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post #1190 of 1560
5/20/08 at 11:17am
Are there any differences between the UA, NA and GA versions of the REG101/REG102?
I'm just compiling my BOM from Farnell and the UA's are stated as no longer stocked.

Also, is it a problem if instead of 30pF, the crystal is 20pF, the frequency remaining the same, 12mhz?
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post #1191 of 1560
5/20/08 at 12:31pm
Quote:
Originally Posted by DolbyR View Post
Are there any differences between the UA, NA and GA versions of the REG101/REG102?
I'm just compiling my BOM from Farnell and the UA's are stated as no longer stocked.
Yes, they're different packages. Unfortunately only the UA will fit the board. TI is apparently having trouble keeping up with demand on these, and none are slated to be available for some time. It's a problem at the moment for those trying to build AlienDACs.

Quote:
Also, is it a problem if instead of 30pF, the crystal is 20pF, the frequency remaining the same, 12mhz?
The frequency must remain the same, otherwise any parallel resonant crystal should work fine, but you may need to change the load capacitors. If the crystal you buy is 20pF instead of 30pF, just change C11 and C12 to match (~20pF). It's not critical though and will probably operate fine with the 30pF caps.
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post #1192 of 1560
5/21/08 at 2:16am
Thanks for the fast reply Error401.
Now...more wortless questions...
Does anyone have any experience with Samsung caps, as I'm ordering some things from Jeff, i'm would I be better of taking what he offers for the SMD caps or would the Samnsungs (C0G and X5R, 5% and 5-10% respectively) be just as good (i can get these locally).
For the SOHA I used UniOhms resistors but I guess for the Alien I'll really get the Vishay-Dales (unless someone tells me the difference wouldnt be really that great )
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post #1193 of 1560
5/21/08 at 12:54pm
Quote:
Originally Posted by error401 View Post
TI is apparently having trouble keeping up with demand on these, and none are slated to be available for some time.
As far as I know, TI only tools up to make these once or twice a year.

I ordered a nice batch of parts from Handmade last night (including Muse ESs). I tried valiantly to get the whole thing coordinated through Paypal, but that got hosed up due to the address I somehow have as confirmed. Oy. I know why Handmade prefers credit cards! Ah well, I'll try again tonight. Once done, all I will need for my two Aliens will be cases. Finally!
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post #1194 of 1560
5/21/08 at 2:39pm
Quote:
Originally Posted by bhjazz View Post
As far as I know, TI only tools up to make these once or twice a year.

I ordered a nice batch of parts from Handmade last night (including Muse ESs). I tried valiantly to get the whole thing coordinated through Paypal, but that got hosed up due to the address I somehow have as confirmed. Oy. I know why Handmade prefers credit cards! Ah well, I'll try again tonight. Once done, all I will need for my two Aliens will be cases. Finally!
Don't get me wrong - I love Handmade Electronics. They are one of our best DIY-parts vendors.

However, when it comes to Paypal, I'm afraid they don't have a clue. They don't interface to it at all, really - expecting a customer to write down the total, then access Paypal separately and manually make a payment to Handmade's Paypal account.

That's not exactly a programmed solution - people interface to Paypal all the time. It's less troublesome than interfacing to the Post Office, IMHO. Still, in spite of that small flaw - Handmade is the best.
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post #1195 of 1560
5/21/08 at 3:18pm
Quote:
Originally Posted by error401 View Post
The frequency must remain the same, otherwise any parallel resonant crystal should work fine, but you may need to change the load capacitors. If the crystal you buy is 20pF instead of 30pF, just change C11 and C12 to match (~20pF). It's not critical though and will probably operate fine with the 30pF caps.
Use the following equation to calculate the load capacitance (CL) and tell me if that is correct.



CL1 and CL2 are the load capacitors and Cs is the circuit stray capacitance (usually 3 to 5 pF)
LL
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post #1196 of 1560
5/21/08 at 5:04pm
Quote:
Originally Posted by MisterX View Post
Use the following equation to calculate the load capacitance (CL) and tell me if that is correct.



CL1 and CL2 are the load capacitors and Cs is the circuit stray capacitance (usually 3 to 5 pF)
I'm not doubting you, as to be honest I have no idea, I asked a question about crystal load capacitors before and didn't get a very satisfactory answer IIRC.

But following that equation, using the parts suggested for the Alien DAC, a crystal with CL=30pF and then C11 and C12 = 32pF. Doesn't CL actually work out to be around 20pF or so, depending on the value of Cs ?
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post #1197 of 1560
5/21/08 at 7:20pm
Quote:
Originally Posted by MisterX View Post
Use the following equation to calculate the load capacitance (CL) and tell me if that is correct.



CL1 and CL2 are the load capacitors and Cs is the circuit stray capacitance (usually 3 to 5 pF)
You're right of course. I never really thought about it, to be honest, and have always just used the quoted value directly. Thanks for the correction, I don't know why I didn't think of that myself.

Either way, it's not too critical. A few dozen ppm error isn't going to break anything in this application. Besides, the originally specified crystal and caps aren't correct either!
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post #1198 of 1560
5/21/08 at 9:52pm
From the datasheet:

Quote:
The PCM2702 requires a 12MHz (±500ppm) clock for USB
and audio functions
You're right....no point in arguing about a few measly PPM's with that kind of a tolerance.
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post #1199 of 1560
5/22/08 at 1:53am
Quote:
Originally Posted by tomb View Post
That's not exactly a programmed solution - people interface to Paypal all the time. It's less troublesome than interfacing to the Post Office, IMHO. Still, in spite of that small flaw - Handmade is the best.
Agreed. And I got bit by it. Yeah, I was a little surprised at the process as well. A bit of extra work for the customer to do themselves. I think my only real gripe is that I paid with instant transfer, but when they refunded my money due to the address mixup, they do not have instant transfer, so I get to wait five business days. Odd. Ah well, I do love their selection, so I'll take another go at it next week...with my credit card!!! I want my Muse ESs!!!
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post #1200 of 1560
5/22/08 at 3:45am
At Mouser it seems to say the regulators can ship in 10 days:
REG101UA-3.3
REG101UA-5

...the adjustable one isn't available till hell freezes over, but these will work fine afaik.
What do you think? I was going to order some soon too.
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