FDA-1 PCM1794A DAC Manual_r6

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Last update on Jan 26, 2012:

Note that the 50% OFF sales is still on-going.  No re-issue due to shortage of Toshiba parts like 2SC2240, 2SA970, 2SC1815, & 2SK30A.  The power transistors 2SC3421 and 2SA1380 have be replaced by another matched pair already.  Also 0.047u will be replaced by 0.056u same panasonic ECQ-V film capacitor.  For Dale, some of them may be replaced by Vishay MRS25 resistors depending on stock level.  Note that MRS25 is 50ppm part while dale is 100ppm part.

28 pieces PCB to go!

Note that Single Ended kit uses one pcb and Full Balance kit uses two pcbs.

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On board, there is a I2S connector and thus the clock jitter measurement is taken at the MCLK, BCLK, LRCLK locations.  The jitter at MCLK from 48k to 192k Fs is from 10 to 13 pico second respectively which are excellent.  In fact the MCLK is taken directly from the onboard crystal oscillator after the buffer logic IC.  For jitter at other clock like BCLK (Bit Clock) and LRCLK (Word Clock, Fs), they are as high as 800 pS or above.  For any DAC using the MCLK as the clocking reference (like FDA-1), the result should be very good.

Attached is the document of jitter measurement for reference:

Jitter measurement by Lecroy DDA-120

From all the measurement, the lowest jitter mode is to set the output of the USB 2.0 at 24 bit with 48k Fs.

With a more accurate period jitter machine Wavecrest DTS-2070C, the jitter at MCLK is measured at only 4.6ps.  See attached document:

Jitter measurement by Wavecrest DTS-2070C

 I have also taken some measurements of DAC chips as in attached file.  They are WM8804, CS8416, DIR9001; SRC: CS8421, SRC4192 & AD1896.  The measurement is on the MCLK (master clock) of the DAC FDA-1 in different test version durng development.

Jitter Measurement

1. Out of 5, only two probe tip heads are working and thus I am able to recover two probes in full working conditions after repairs and adjustments.  Thus it is a real bargain for me!

2. One box is with two burnt logic ICs inside and no way I can repair it!  What I can do is just repair the connection cable.

3. Another box is working but with X10 not functioning.  Guess there is some logic defective inside.

4. The other box is with unknown conditions as I have not tested it with a working probe tip head.  Believe it is working conditions as I check the voltage at probe tip socket is normal conditions.

5. All the 5 connection wires were repaired.  The usual defective point is the probe head joining point loose and control wires may be broken or intermittent connection.  I peel off more plastic of the coaxial cable ground and wrap it with some ground shielding cable and then solder the ground wire onto the frame of the tip socket end.  After that wire connection is checked one by one by multimeters.

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This P6247 differential probe is very good for testing high frequency signal as it only has below 1pF capacitance value. It also has x1 and x10 selection, AC and DC mode plus the bandwith limit of 200Mhz.  I use that with a tek 1103 probe power supply and then I can connect it to any measurement equipment with 50 ohm termination like oscilloscope, frequency meter, spectrum analyzer etc…

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Here I put up some photos which will be very easy to understand more about the repair:

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As in the past, the match from part to part is within 0.2mA assurance but you will get normally within 0.1mA tolerance.  The Idss accuracy is about +/-0.1mA due variation of equipment and temperature during test.  Special requirements may or may not be fullfilled and it is a case by case discussion.

Price is in the Store page.