Deciphering an ADC board's SMD components

[sky_123]

Hello,

As some may know, KNJN's boards are not open (no circuit diagrams or source code is supplied). I made the mistake
of purchasing a couple of boards a while back, and I'd like to use one for an experiment, but I wanted to get an idea of the circuit.
All that is supplied is a block diagram. I'm guessing there is a high speed input buffer amp (FET based), and
some adjustable VSS to provide an offset. I've attached hi-res images of the board if anyone is good at detective
work. The SOT-23 devices hi-res images are also attached in the third image, marked A/B/C/D/E. If anyone can identify any/all of the five devices,
it would be great (I've tried some googled SMD marking sites, but I'm not familiar with any decent sites for this).
There is also a small 5-pin device marked 'SACI' - maybe a serial EEPROM for the DAC settings.

 

[rohitkhanna]

SMD markings interpretation is almost an art, since there are so many overlapping markings from various mfg's, and constant introduction of new devices/ package types etc etc.

Here is a few sources which might help--

elektronik.googlecode.com/files/SMD_Catalog222.pdf
https://www.s-manuals.com/smd

 

[sky_123]

Hi Rohit,

Thanks for the links, it helped to decode the D2p marking to be BCW32.
For now, I've decided to disconnect the amplifier from the ADC on the board, and implement my own amplifier on a separate board.
I had wanted to figure out how the board implemented it's gain and offset adjust, but I have a wideband FET amp circuit I'll
try to implement an offset with.
I tried connecting the board to a 'open bench logic sniffer' last night, it makes a cheap scope, and it's open source
unlike KNJN. I had to write a program to convert the saved file into a csv format that Excel could convert into a graph, so
it's still primitive, but workable.