The OS-CONs near the DACs are for VREF and VCOM while those near the ADCs are for VREF on the bottom side of the board there are Panasonic 10uF directly soldered on the 100nF bypass for VD and VA of the DACs and ADCs, and on the 100nF which bypass the two VCOM( of each ADC.Īs You can see in Fig. In addition to this for sure also the complete recap of the DSP board with OS-CONs around the ADCs, DACs, and CS8240 played an important role. I didn’t take any photo, but I can confirm that the scope traces with the stock capacitors were remarkably worse than the above, in both the 5ms and 10uS scope resolution the immediate result of this mod has been a reduction in the annoying hiss You can clearly ear when the DCX is connected to the amps. The 3.3V and the 5V remain within 10mV it is a good result considering that the 5V goes directly to the VA pin of the CS8420 and has a direct impact on jitter. The +-15V is the worst, with more than 30mV spikes over the fundamental, and the 8.7V showing a little more than 20mV of the same spikes. 7 ), but with a strange “shadow” surrounding it this comes clear at 10uS resolution, where we can really see over imposed spikes with 8uS period, which translates into 125KHz frequency. The 3.3, 5 and 8.7 have a ripple of about 15mV peak to peak, but it is not clear to me where the 200Hz frequency (5ms period = 200Hz) comes from … The +-15V seems very clear with few mV ripple (Fig. Then I took some photo of the supply voltages at 10mV per vertical division, with the first run at 5mS horizontal division and the second at 10uS horizontal division Here is a snapshot of the replacement (Fig. The +-15V line has 820uF for C4 and C5 and 47uF for C1 and C2
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