Main board PCB 19.1/19.3/19.4

original source1)

The main board PCB 19.x has the following through-hole technology (THT) components.

count part note
3 DA103C - Transformer Murata Power Solutions
1 Inductor - 3.3 mH Taiyo Yuden
1 USB Mini-B Connector, PCB mounting, 90°
1 1×4 Header, straight, Pitch 2,54 (only 19.1/19.2/19.3)
1 1×5 Header, straight, Pitch 2,54 (only 19.1/19.2/19.3)
1 2×5 Header, straight, Pitch 2,54 (only 19.4)
1 1×2 Header, straight, Pitch 2,54 (only 19.4)
1 2×3 Header, straight, Pitch 2,54 (only 91.1/19.2/19.3)
1 Jumper (only 91.4)
2 Jumpers (only 91.1/19.2/19.3)
1 Piezo Audio Indicator
1 Crystal, 8.0000000 MHz
1 Crystal, 25.000000 MHz
3 Pushbutton 6x6mm, height: 4,3mm, vertical
1 RJ45 Modular Connector
1 HanRun (HR911105A) RJ45 network connector with integrated magnetics
1 F-Connector, PCB mounting, 90°
1 SMA Connector, PCB mounting, 90°
1 Ground Socket (only PCB 19.4)

Some of the THT components may have been soldered because they were required to install the initial firmware.

The DA103C Transformers have a white dot at one corner. On the main board, there are white dots printed at the placeholders for the transformers TR1, TR2, and TR3. The white dots at the transformers must match the white dots at the main board.
The 3.3mH inductor is L403.
Crystal Q1 has a frequency of 25 MHz, crystal Q2 has a frequency of 8 MHz
Some Piezo Audio Indicators has a ’+’-mark, which should match the ’+’-mark on the board. (If there is no ’+’-mark, then the orientation is not important.)
(only 19.1/19.2/19.3x)
(only 19.1/19.2/19.3)
(only 19.4)
All other components can not be soldered at wrong places because of their physical layout.

At switch S1 on PCB 19.2 you have to connect pin 5 and pin 6 by a jumper. This turns the board on, if an USB power supply is connected, the red rectangle in the image above. You have also to connect pin 1 and pin 2 by a jumper such that the pre-amplifiers get power, the green rectangle in the image above. Note that these jumper settings are different at the early board PCB 19.1. Please refer to the circuit diagrams. At 19.4 you have to connect the two pins of the power jumper.

The router is connected at the RJ45 network port with a shielded twisted pair network cable (FTP, STP, S/STP, or S/FTP).

Digital filter option

The complete digital filter option consists of

count part
4 digital filter ICs (LTC1569-7)
8 SMA Connector, PCB mounting

In general, it is not necessary to install the digital filter ICs. The system also operates without them. However, if you want to experiment, or if you have extremely strong interferences at frequencies above 20kHz, you can try to get better signals with the digital low pass filter ICs. Since the digital filter ICs are relatively expensive, you should test one filter IC at one channel, preferably at the E-Field channel. If the desired effect is achieved, the other channels can be upgraded.

The digital filter ICs have a point at one corner of the housing. This point identifies Pin 1. It must match the white dot on the main board. You need a soldering iron with a small tip to solder the SOIC-8 package.

You have to close (solder) Jumper J0, otherwise the firmware will not recognize the filter ICs, and thus will not offer you the possibility to adjust them.

All inputs and outputs of the amplifiers are passed via buffer amplifiers to SMA connectors. If these connectors are installed, then the signals can easily be monitored with an oscilloscope or an FFT analyzer. There are various programs for signal analysis, if the output of the preamplifier is passed in via a sound card.

Voltage regulator extension

original source2)

Unfortunately, the voltage regulators of the boards PCB 19.1 and PCB 19.2 are not adequately adapted to the current consumptions of the boards. This problem is eliminated by the piggyback board PCB 21.

The schematic of the board can be found here.

PCB 21 is manufactured on a panel with severals boards and thus may have overhanging edges. You should file off these edges.

The voltage regulator IC502 should be unsoldered from the board. Please do not operate with both voltage regulators. They can act against each other.