The first thing that we have to do before doing some mods activity is to find out who is where, why, and doing what. We can easily exclude when and how 😉
First, we need a AVO Meter. Any brand will do, as mostly we are testing for continuity only. Mostly, it will produce a ‘beep’ sound if it detects conductivity. Any cheap meter will do, started from $5. But I prefer a good tool, so I use my Sanwa PC510.
Second, you will need a schematic of some vital components (like opamp, DAC chip, etc). Off course you can easily view with your laptop or PC or even print them. But I believe most of us should have a smartphone with data connection. So checking them online with your smartphone (without printing them) would become a very handy task.
Last but not least, you will need a multi color writing pen and some papers. Draw some basic layout, like DAC chips, some opamps, capacitors, etc there.
If your circuit has some removable chips (with socket), then it’s good to remove them first. It’s gonna be easier to trace without the chips plugged in.
Off course I assume that you will have some basic understanding of opamp, power supply layout, and some basic electronic arrangement. Otherwise, this process will become a nightmare than a fruitful result 😉
What we are looking for is to find whether the capacitor is related with power supply or coupling. As surely different purpose should have different capacitor (at least from my perspective). And by understanding who is doing what, we can find a right component for the right job. This is where the continuity test of the multitester will play an important job. It might take several hours to trace, but most of the time, when you have enough experience, you should be able to guess who is where and what it’s doing. This process merely only to confirm your guessing 😉
Actually if the PCB is single or double layer, you can easily use a high power light source to see through the PCB from the other side. I would rather call this a ‘poor man’s xray’.
Slightly out of the topic, this ASUS Xonar Essence One uses Nichicon ‘Audio KT’ capacitor.
Not a bad capacitor, but surely not the best (and not my type).
WIMA also found around. Again, not my favorite but I think it’s gonna be tough to find substitute capacitor with current space and layout.
Two BurrBrown PCM1795 (one shown on picture below for one channel) should fit the D/A function nicely on this level.
AKM AK4113 as digital receiver. Also should be a nice complementary for PCM1795.
Tracing the power supply PCB is relatively easy as it has 3 lines, with capacitor on each line. Logically we can easily guess how does it work before even powering up the AVO Meter. I think it’s a good start to bring confidence before moving into more complex part: the audio board PCB.
If you have this ASUS Xonar Essence One and you plan to modify it, then I would encourage you to start tracing the power supply PCB first. It would be a nice learning session and good start to adept playing with such black thick PCB (where your poor man’s xray technique won’t work). Once you have enough confidence, then the next part is the audio board PCB which is quite challenging (I would rate it as medium level complexity). Be careful when de-soldering the component. Although the PCB is good one, but the holes are quite small and surely through-hole type. So it might trouble us when we plan to change with a new component with bigger lead diameter.