HEC part II
Posted 17th June 2010 at 05:07 AM by abraxalito
Updated 8th September 2011 at 03:04 AM by abraxalito
Updated 8th September 2011 at 03:04 AM by abraxalito
Here's a pic of the underside of the DAC before I started hacking tracks. Bottom left area is where the digital circuits are, with ground plane. Top left are the analogue output filters. Right is the caps, rectifiers and regs of the power supplies - digital at the bottom and analogue at the top.
The AD1955 sits about the centre of this pic, and if you look closely you'll notice two small holes I drilled in the groundplane either side of it where I will later install the 10uF decouplers.
The second pic shows the component side, prior to any hacks - the 'virgin board' if you like, although sullied by the two small holes near the DAC chip. The analog supply is pin15, that's at top left.
Third, here's the meat of the digital circuitry and I've already added one decoupler to the AVDD (analogue positive supply). To the right of the 24.576 XTAL (not required) is the DIR9001 SPDIF receiver. The DIL chip is a multiplexer allowing both USB and SPDIF input auto-selection. The SPDIF input comes in on the blue/white twisted pair and into an RS422 receiver (the topmost SO16 chip). The two headers below the AD1955 allow external data and clock signals to be inserted. The 7805 at far left is for the analogue supply to the AD1955.
The AD1955 sits about the centre of this pic, and if you look closely you'll notice two small holes I drilled in the groundplane either side of it where I will later install the 10uF decouplers.
The second pic shows the component side, prior to any hacks - the 'virgin board' if you like, although sullied by the two small holes near the DAC chip. The analog supply is pin15, that's at top left.
Third, here's the meat of the digital circuitry and I've already added one decoupler to the AVDD (analogue positive supply). To the right of the 24.576 XTAL (not required) is the DIR9001 SPDIF receiver. The DIL chip is a multiplexer allowing both USB and SPDIF input auto-selection. The SPDIF input comes in on the blue/white twisted pair and into an RS422 receiver (the topmost SO16 chip). The two headers below the AD1955 allow external data and clock signals to be inserted. The 7805 at far left is for the analogue supply to the AD1955.
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