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Guide me through assembling DAC board?
Guide me through assembling DAC board?
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Old 20th October 2019, 06:00 PM   #1
mark3141 is offline mark3141  United States
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Join Date: Feb 2013
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Guide me through assembling DAC board?
Default Guide me through assembling DAC board?

I've wanted to get some hands-on experience playing with circuits and such so I bought a USB 8 channel DAC kit and was hoping I could find some folks here that would be willing to guide me through the assembly. In exchange, I'm willing to write up the process as a guide for others in the future.

The board itself is an 8 channel ES9016 board here with this reclock between the USB input and DAC and the opamps here. I'm using this and this as the power supply.

My main questions are these:
1. What needs to be soldered and what does not? The site states "SMT components soldered, thru-hole components are not soldered", but it's not clear to me which is which. It is especially not clear how the opamps are attached to the board.

2. How consistent do the top/bottom lengths of the opamp pins need to be? For example, is it a problem that one side is longer as seen in the picture? Is it also ok if some opamps are connected by two sets of two pins (or one and three pins) instead of a single set of four pins? I had a lot of trouble resizing what was sent to fit.

3. What is the best order to approach assembly? Since the majority of my solder experience is with larger cables, I don't know what to expect when working with something this small.


4. How do I best go about getting power to each of the power supplies while minimizing the amount of outlets needed to power the DAC? I'd like to avoid having to provider a separate power outlet for each of the power supplies.

I'm sure there are more that will come up in the course of doing this, but any input on any of the above questions will be greatly appreciated. Thanks!
Attached Images
File Type: jpg resize_board.jpg (572.2 KB, 150 views)
File Type: jpg resize_opamp.jpg (611.8 KB, 152 views)
File Type: jpg resize_pins.jpg (659.4 KB, 150 views)
File Type: jpg resize_ps_12v.jpg (537.6 KB, 150 views)
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Old 22nd October 2019, 01:01 AM   #2
PaulFrost is offline PaulFrost  United States
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Join Date: Aug 2017
Location: Tucson, AZ
Hi Mark,

Here are my brief comments:
1. If it says SMT components are soldered, that means that all the Surface MounT components are pre-soldered. This is good for you as surface mount components are more difficult. You should only need to solder the items with wire leads, like resistors, caps, and connectors.
2. They do not need to be exactly the same, but it is possible the longest lead will bottom out before the shorts make contact. If you are struggling to break them off at the correct interval, I suggest you use either two pairs of needle-nose pliers to do the snap, or a fine pair of wire cutters to make the cut. You can order additional headers for pretty cheap off of Digikey or SparkFun. The issue with using 1+3 or 2+2 is that they will be harder to align. You will probably burn your figures trying to hold it in place /
3. Aways go smallest to largest components. Know your solder, iron, and flux. I use Kester red label, leaded solder that has water-soluble flux. You can also get the Kester water-soluble flux pen as well. Flux is like thermal butter that helps the two pieces of metal get to temperature faster.
4. You can power the two boards with the same cable if you wire it correctly.

Goodluck!
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Disclaimer: Employed by Texas Instruments as an Applications Engineer with Precision and Audio DACs
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Old 22nd October 2019, 10:03 PM   #3
mark3141 is offline mark3141  United States
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Guide me through assembling DAC board?
Thanks, Paul. I almost feel dumb after reading your response to 1. I didn't realize the site was saying SMT is pre-soldered. Now that part of it all makes sense.


Based on your recommendation, I've ordered better flux and solder and will practice quite a bit before getting starting. I've also ordered headers and will start over with those.

I hope to have some updates soon...
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Old 11th November 2019, 12:07 PM   #4
mark3141 is offline mark3141  United States
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Guide me through assembling DAC board?
I managed to get everything assembled, but I am only getting output from 5/8 channels. I couldn't find any info on how to attach the RCA jacks so I soldered them to the board, and that may be my issue, especially since it was a really bad soldering job. Any advice on troubleshooting?
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Old 11th November 2019, 04:32 PM   #5
Markw4 is online now Markw4  United States
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Do you have an oscilloscope for troubleshooting? If not, you might be able to use an AC voltmeter or even a little audio amplifier such as a guitar amp for signal tracing.

There are normally 3 opamps per channel that convert the dac output currents into output voltages that would then go to the RCA output jacks. Don't know if you can identify any of that circuitry?

If so, you just play some kind of test signal or music through the dac and follow it from the dac to the RCA jacks. If it gets lost at some point, then your problem is right around in that part of circuit.

Hopefully, you have your opamps in sockets so that they are easily removable?

Otherwise, you could post some good, clear, well-focused, close-up pics of your work, the bad solder joints you suspect, etc., and let us take a look. Maybe we can see something that could be your problem.
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Old Yesterday, 06:18 PM   #6
mark3141 is offline mark3141  United States
Still learning...
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Join Date: Feb 2013
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Guide me through assembling DAC board?
I can identify the opamps themselves, but I don't know how to take the signal in or out of them. I could check for a signal with an AC voltmeter if I knew where to measure (no o-scope yet).
Since the files are large, here is a link to pictures showing the opamp and RCA soldering. It's certainly not pretty 🙂

Thanks for the help.

DAC - Google Photos
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Old Yesterday, 06:26 PM   #7
Markw4 is online now Markw4  United States
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Those pics look pretty bad. What solder and soldering iron did you use (pics please)?

Looks like one of the opamps has its pins shorted together with solder. Also, some of the output connectors are not soldered at all.

You will need a proper solder iron for electronics work and proper solder.
In addition, you will need some solder wick for removing excess solder you have already applied. Some extra paste-flux would likely be useful for that process.

After we see what you are used for the existing soldering then we can figure out what you need to do next. You might that find watching some youtube instruction on electronics soldering would be helpful. A short movie I made to help people in another thread see how an opamp might be soldered to an adapter or PCB can be found at: Dropbox - SMD Solder.MOV ...You may notice that solder on the tip of the iron tends to move away from where you want to solder to go. That's because it goes to where more heat is, and since one side of the iron is touching the PCB that side if the tip is being cooled. If that happens you can do what I did which was to rotate the iron in my fingers to bring the solder around to where it could make contact with the PCB and opamp pin. Once the solder makes contact then heat transfer from the iron to the PCB and pin are greatly improved. As that area heats up then the solder will flow there. However, it needs to be done quickly to avoid burning up the flux that protects the solder from oxidation. One can practice such things with iron cold. Once you can manipulate the iron in the necessary motion, then try it with a test board and test component before trying it on your project board. You need some practice before risking damage to costly equipment. There is much more that can be said, but let's take it in small steps for now.

Troubleshooting with power turned on should only be attempted after all plainly visible problems have been fixed.

Last edited by Markw4; Yesterday at 06:46 PM.
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