[FallenAngel]

Try the flood and suck technique:

Put a length of solder across the entire PCM chip, then (not too quickly) run a hot iron over it so it looks like a huge amount of solder covers all the pins and solder pands. Put a length of desoldering braid over the pins and heat it up just like you did with the solder, run the iron slowly from one side to the other.

I noticed that this works quite well, and that desoldering braid works much better if there is a lot of solder there.

 

[whiz]

i burned my dac once again!

(check page 28 on this thread)

How did it happen?
I had an RCA to RCA cable...and i cutted the one end so i can have RCA to naked cables so i can connect my alien dac to an amp!
when i disconnected the cable from the amp...the naked end bridged itself
so i burned one of the outputs!

the chip goes very hot! but it still works...

 

[Gross]

I would also suggest removing the capacitors (or next time doing them last) as it will be much easier to get your iron in to solder the small SMD stuff.


Quote:

Originally Posted by jornterpstra /img/forum/go_quote.gif Ok so the smd soldering didn't go as planned i need some thinner solder i think, anyway i messed up on some spots, like the spot for R32/C32 and pin 4 at the 102UA. and probably the 2702, but think i can fix those on the 2702... so, pin4 on 102ua and the r32/c32 are bridged as you can see in the pic i attached. Tried desolder braid, but that didnt work at all this time. any suggestions on how to fix this? or is the board fubar now? thanks. (have parts for 1 more luckily )

 

[sbyers77]

Quote:

Originally Posted by jornterpstra /img/forum/go_quote.gif Ok so the smd soldering didn't go as planned i need some thinner solder i think, anyway i messed up on some spots, like the spot for R32/C32 and pin 4 at the 102UA. and probably the 2702, but think i can fix those on the 2702... so, pin4 on 102ua and the r32/c32 are bridged as you can see in the pic i attached. Tried desolder braid, but that didnt work at all this time. any suggestions on how to fix this? or is the board fubar now? thanks. (have parts for 1 more luckily )

Whats the wattage on your iron and are you using flux? Alot of those pads look like they have a cold-solder joint going on (judging by the C2 and voltage regulator pads). Apply some flux and make sure your iron is hot enough to completely melt the solder. I see you are from the Netherlands, so double check your solder type, it might be a no-lead variety that has a higher melting temperature than conventional lead based solders.

 

[jornterpstra]

Ok, cleaned all the bridges on the pcm2702, that one is fine now as far as i could see.
Just got that mess on the 102ua and the spot for the resistor left. both are probably connected to the copper of the pcb.
The leg on the 102ua thats connected to the copper is the GND leg, does that even matter ?

as for the resistor to the copper, doubt i can fix that

Maybe i'm better of removing the regulator ? and make it an usb unregulated one.

 

[Seaside]

Quote:

Originally Posted by jornterpstra /img/forum/go_quote.gif Ok, cleaned all the bridges on the pcm2702, that one is fine now as far as i could see. Just got that mess on the 102ua and the spot for the resistor left. both are probably connected to the copper of the pcb. The leg on the 102ua thats connected to the copper is the GND leg, does that even matter ? as for the resistor to the copper, doubt i can fix that Maybe i'm better of removing the regulator ? and make it an usb unregulated one.

Your PCB looks alright.
Only thing you need to do is clean excessive solders off from it.
Cleaning 102ua would be way easier than cleaning 2702.
What you need is desoldering braid, follow what FallenAngel said at that chip too. It is fairly easy to clean those mess off. Double Triple check on all soldering point, makes sure you don't have any cold joint. After that, make sure you clean the PCB so that there is no flux on it.

 

[FallenAngel]

Hey guys,

I've been using BlackGate NX HiQ series caps in all my AlienDACs and they sound great, but I'm just wandering how much better they could sound with some other film caps. Of course, within reason, for a DAC which costs about $50 to build, I don't really want to put a pair of $20 caps.

Basically, wandering if anybody has used simple the cheap caps like MKP/MKS series caps or perhaps some boutiques like Mundorf / AuriCap / MultiCap (the cheaper PPMFX series or more expensive types). Maybe some NOS Sprague Vitamin Q?

Also, how low can I reasonably go in terms of capacitance here? 1uF?

 

[error401]

Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif Hey guys, Basically, wandering if anybody has used simple the cheap caps like MKP/MKS series caps or perhaps some boutiques like Mundorf / AuriCap / MultiCap (the cheaper PPMFX series or more expensive types). Maybe some NOS Sprague Vitamin Q? Also, how low can I reasonably go in terms of capacitance here? 1uF?

I'm not too sure why Alf specifies such a high capacitance here, probably because he doesn't have room on the board for decent film caps and if you're going to put in 'lytics, may as well go for the higher value. As far as I can tell there's no other reason to use quite such a high value - the DAC chip isn't powerful enough to power low impedance loads like headphones, and with high impedance loads the filter response isn't too horrible with just 1uF there (-3dB at about 16Hz with 10k load, around 3Hz with 50k load).

You might want to go up to 4.7uF but even 1uF is probably fine for most applications. Personally I've been omitting CL/CR and R14/R15 and instead relying on the higher quality film caps in my amps. I don't have easy access to boutique electrolytics and I trust that the capacitors in the amps are better matched since the resistance component of the filter is known, rather than in a source where you need to account for all possibilities.

I've put some Panasonic ECG 0.47uF after an AlienDAC in my latest project (not done yet, mind) and I expect it to have good bass extension, the -3dB should be around 4Hz if I remember my simulations correctly.

 

[FallenAngel]

Thanks error401

I'll probably try a couple of 1uF Sprague Vitamin Q's there

Oh, and if you need access to boutique electrolytics, check out www.partsconnexion.com, Head-Fi sponsor located in Ontario, expedited shipping to you should be pretty cheap and their prices are great.

 

[Gross]

Well, My post just 10 above this one explains that a 1uf output cap feeding into a crossfeed does not work. I would go minimum 4.7, and if you can go larger, that is even better.

 

[AndrewFischer]

I've been listening to my just completed second Alien DAC.

Burn in setup is Dell Precsion 380/ iTunes 7 / Alien DAC / PPA V1 / Senn 580s with HD 650 cable.

It sounds darn good, even with Elna RFS electrolytic caps in CR/CL. Way better than the Audigy in this computer. I'll be changing to film caps with my next parts order.
I cooked the 2702 on the first one. I'll get around to fixing it eventually.


Thank you Burr-Brown Japan and [size=large]Thank you Alf.[/size]

 

[Ikarios]

I really want to get started in my AlienDAC, but there are a few questions that are stopping me from ordering.

1) What is everyone getting for CL/CR from Mouser? The two caps that I wanted (BlackGates, Nichicon KZ) aren't available.
2) Is there a reason everyone uses RCA jacks? I want to use this as a portable DAC, so I'm assuming a mini jack would work as well?
3) Is there a place that has either the BlackGate and the REG101UA-A together, or the BlackGates and the Hammond 1455c Black case together? Out of curiosity... I can't seem to get a suitable single-vendor order from Digikey or Mouser.

 

[Yen]

Quote:

Originally Posted by Aflac /img/forum/go_quote.gif I really want to get started in my AlienDAC, but there are a few questions that are stopping me from ordering. 1) What is everyone getting for CL/CR from Mouser? The two caps that I wanted (BlackGates, Nichicon KZ) aren't available. 2) Is there a reason everyone uses RCA jacks? I want to use this as a portable DAC, so I'm assuming a mini jack would work as well? 3) Is there a place that has either the BlackGate and the REG101UA-A together, or the BlackGates and the Hammond 1455c Black case together? Out of curiosity... I can't seem to get a suitable single-vendor order from Digikey or Mouser.

1. Digikey has Elna RFS, which is (I think) SilmicII series. Silmic II is one of the recommended by Support website, just as Blackgates and Nichicon Muse.

2. You can use any jack you want. Mini is just as ok as rca.

3. Digikey, with Elna SilmicII.

 

[Jrossel]

Quote:

Originally Posted by Gross /img/forum/go_quote.gif Since the resistance of the crossfeed is going to be somwhere in between 1k-2k, If I did my rough calculations correct, seeing a 2k load, a 1uf capacitor will form a highpass crossover at 80hz, which correspond exactly with what I am hearing. A 4.7uf should get me down to 17hz, so I guess I am off to see what polypro cap I can find in a 4.7uf value.

Thanks for explaining this Gross. I am trying to spec out a really nice coupling cap for a kit that I am going to provide. I figure I will have Black Gate NX for the regular kit and 4.7uF Auricaps by Audience in the high end kit.

JR

 

[AndrewFischer]

Quote:

Originally Posted by Aflac /img/forum/go_quote.gif 3) Is there a place that has either the BlackGate and the REG101UA-A together, or the BlackGates and the Hammond 1455c Black case together? Out of curiosity... I can't seem to get a suitable single-vendor order from Digikey or Mouser.

Not that I'm aware of. If you want Black Gates you will have to get them from a specialty vendor.

I split my order between Mouser and Digikey. If you are building at least two, you can reach the minimum order value at both vendors. I posted my BOM, with Mouser / Digikey partnumbers somewhere in this thread. Shoot me a PM if you can't find it and want a copy.

Mouser doesn't stock the Burr-Brown chip. Digikey does. If you are going to use a single vendor, I'd try Digikey.

I built mine with the Elna RFS caps. RFS is Silmic II. That's Elna's best audio electrolytic. Not bad sounding at all.