ezDAC v.1.5 Builders Thread

[PJN]

Troubles with EZDUAL

Hi Guys,

I put together my EZDual tonite, and am having problems with it. Trafo reads 15.1v - 0v - 15.1v, the centertap is hooked to AC2, something seems to be pulling current with no load. I get 13.4V -0v - 13.4V from the trafo when hooked up to the board. With power hooked up R2A,B,C get warm. Even if I disonnect AC3 and leave AC1 hooked up R2A,B,C gets warm. I checked for obvious shorts, but so far I haven't been able to find any. I'm pretty much a newby at electronics, and any help would be appreciated. I've attached some pics of my build.

Thx,

PJN

 

[paulb]

First check the polarity of the tantalum capacitors C4,5,7,8. Especially C7 & 8, the + side of each should connect to Ground.
Then check the DC output voltage. If it's slowly decreasing after you wait a few seconds, it is probably those capacitors. I'd bet on C8 causing the problem.
Oh, yes, wear eye protection! They can explode.
If you know for sure that a tantalum capacitor has been reverse- or over-voltaged, replace it even if it seems okay.

 

[6h5c]

Hi All,

I'm starting to order parts for my DAC board. On the BOM posted for the 1.5 EZDAC on Evan's site C1,2,4,5,7,8,10 & 12 are shown as 10 uF, however when I go to the digitkey number shown on the BOM they are shown as 100 uF, on the digitkey site. Could anyone please let me know the right value ?

Thanks,

PJN

They are supposed to be 10uF, tantalums originally. The 100uF are way too big to fit on the board. You can use the 399-3654-ND if you like, but anything between 10...47uF and 16V or higher is o.k.

I fitted small Rubycon ZA there, here's my BOM.

Regards,

Ray

 

[PJN]

Thanks Paul,

The tantalums are reversed, I wasn't aware that tantalums had polarity and the tiny writing was very hard to see. I'll swap them out and give it another try.

Ray, thanks for the BOM.

 

[6h5c]

Yes, there's a tiny 'plus' sign on the case if you're lucky, sometimes it's only a stripe that indicates the minus.

But it's going to make music now 🙂

Ray

 

[paulb]

They are supposed to be 10uF, tantalums originally. The 100uF are way too big to fit on the board. You can use the 399-3654-ND if you like, but anything between 10...47uF and 16V or higher is o.k.

I fitted small Rubycon ZA there, here's my BOM.

Regards,

Ray

I used 0.1uF ceramics. I plan to parallel the LM337 one with something larger; the datasheet recommends >= 1 uF, I think. The LM317 should be happy with the 0.1uF. If you use something way bigger, I'd recommend parallelling it with a 0.1 ceramic, for low impedance at high frequencies.
http://www.national.com/ds/LM/LM117.pdf
http://www.national.com/ds/LM/LM137.pdf

 

[6h5c]

I'm not using LM317/337 at all now, i'm into the Super Teddy Reg 😀

Ray

 

[PJN]

Hi Guys,

I removed R7 and R8 and replaced them with some electrolytics that I picked up at Radio shack. The good news is that solved the heating up problem, the bad news it that I'm getting+/- 18.5 vdc on the psu outlet. It looks like something is going on in the regulator area. I've attached a pic of some voltage measurements that I've taken. I'm am a bit confused by all of the different BOM's for the PSU so I'm wondering if I used the correct choice of resistors.

PJN

 

[6h5c]

R3/R4 and R5/R6 are not correct. This will give you >25V output. Where did you get those values?

You can read up on how a LM317 works here if you like.

Try 1k1 for R4/R6, this should give you 15V.

Regards,

Ray

 

[PJN]

Hi Ray,

That was a good read, thanks. I got the values for R4 and R6 from the fancy BOM, and the values for R3 & R5 from post #119. I do have some 1K1's so I'll swap R4 & R6.

PJN

 

[6h5c]

I see, both BOM's list values that won't give you 12V or 15V... confusing 😕

Now you know how they work, and able to calculate the correct values for no more troubles in the future 😀

Ray

 

[PJN]

Yea it is confusing especially if you don't know what you're doing like me. I'm glad I have your BOM for the EZDAC.

 

[ezkcdude]

Yea it is confusing especially if you don't know what you're doing like me. I'm glad I have your BOM for the EZDAC.

If you're using the LM317/37, make sure to read the datasheet. The formula for calculating voltage is very simple (assuming the adjust current is negligible). I always assume people don't take my BOM values on blind faith, but I suppose that has not been the case.

 

[paulb]

I did run across this as a USB-SPDIF kit:
The γ1 Modular Miniature DAC configuration C, USB-SPDIF
I want a relay to switch between USB and SPDIF and am looking at if it's feasible with this kit.
Their headphone amps look good too.

 

[PJN]

Hi All,

After watching a primer on SMD soldering on U tube I finally got the courage up to try any start populating the DAC board. It wasn't so bad after all. I do have a question on the orientation of U 4 and U5. In the picture that I've seen folks used the AD8610, but I used the LME4971 since digikey was out of the AD8610. In the attached pic I have U2 and U3 attached, but U5 is just sitting there. Is the LME4971 in the proper orientation to solder in ?

Thanks,

PJN

 

[ezkcdude]

Looks right to me. Pin 1 (not connected) would be the lower left pin there right next to pin 2 which is under the "MA".

 

[PJN]

Evan,

Thanks for the info, I'll try to post more info as the build progresses so others can avoid my mistakes.

PJN

 

[paulb]

I'm happy to report that my ezdac is up and running. I'm working on it as lunchtimes permit at my workplace (where I have access to SMD rework equipment). I used an SPDIF output from my PC, with a small passive network to change from 'TTL' to the proper level, to test it.
Now it's time to turn my attention to the companion USB/SPDIF board that I mentioned in some previous posts. Hope to have a schematic sometime next week.

 

[merlin2069er]

Great, that's good to hear. Hopefully I get mine up and running soon.

 

[mikel_ann]

A new star is born , thanks Evan.

An externally hosted image should be here but it was not working when we last tested it.