Step 3
![[Image: 52689461790_c5d9519f53_b.jpg]](https://live.staticflickr.com/65535/52689461790_c5d9519f53_b.jpg)
Orientation: the top side of the board. The TDA1387 x 8 module will fit approximately in the yellow outline. Note that 16 pins will be hanging in the air. They have no internal connections to the module.
Solder the 40 pin GPIO connector (connector on the under side, pins soldered to the top side).
This would be a good point to recheck all connections and solder joints. If everything looks OK, you can install the module on the board. You can use jumpers to ground the I2S lines at GPIO 12, 35 and 40, and then apply 5V to GPIO 2 and ground to GPIO 39. You should read 1.5-2.0 VDC on module pins 6 and 25. If the board passes, then power down and place the HAT on the Raspberry Pi. Power up Moode. Use either of the generic I2S DACs 1 or 2. Again verify the DC voltage on module pins 6 and 25. Then play a 0dB 50 or 60Hz sine wave track on repeat, you should measure an AC voltage (approximately 1.2 VAC RMS with a 420R I/V resistor) on module pins 6 and 25 with a DMM.
Solder the 2200 uF audio grade electrolytic capacitor with negative in the green hole and positive in the red hole. I like the sound of Nichicon UKA 2200uF 25V. It is large in diameter for the available space and needs to sit above the board to allow access to the left channel audio output. Once the capacitor has been soldered in place, it will limit access to the pin 25 strip, which connects the I/V resistor and output coupling capacitor. The DAC will function without this capacitor, since power supply decoupling capacitors are contained in the module. The capacitor will affect the sound quality of the DAC.
Soldering the electrolytic capacitor should be one of the final assembly steps.
If you have removed the pins from the module and are soldering parts directly to the module, the positive of the cap solders to hole 28 of the module, and the negative is now able to solder to the outermost hole of strip 27.
Be sure to check the polarity of the capacitor. Ground connects to green and positive connects to red. Irreparable damage to the capacitor will occur if this is reversed.
You can press fit different electrolytic capacitor values, and determine the value that sounds best to you. If you like the sound of a lot of capacitance, you can also add capacitors in parallel to the +5V/GND strip, if space permits. If the +5V/GND strips are covered by output coupling caps, there is also open space in the center of the board, between the module and RCAs, that can accommodate a very large amount of capacitance. You will need to solder jumper wires to the +5V and GND strips.
Orientation: the top side of the board. The TDA1387 x 8 module will fit approximately in the yellow outline. Note that 16 pins will be hanging in the air. They have no internal connections to the module.
Solder the 40 pin GPIO connector (connector on the under side, pins soldered to the top side).
This would be a good point to recheck all connections and solder joints. If everything looks OK, you can install the module on the board. You can use jumpers to ground the I2S lines at GPIO 12, 35 and 40, and then apply 5V to GPIO 2 and ground to GPIO 39. You should read 1.5-2.0 VDC on module pins 6 and 25. If the board passes, then power down and place the HAT on the Raspberry Pi. Power up Moode. Use either of the generic I2S DACs 1 or 2. Again verify the DC voltage on module pins 6 and 25. Then play a 0dB 50 or 60Hz sine wave track on repeat, you should measure an AC voltage (approximately 1.2 VAC RMS with a 420R I/V resistor) on module pins 6 and 25 with a DMM.
Solder the 2200 uF audio grade electrolytic capacitor with negative in the green hole and positive in the red hole. I like the sound of Nichicon UKA 2200uF 25V. It is large in diameter for the available space and needs to sit above the board to allow access to the left channel audio output. Once the capacitor has been soldered in place, it will limit access to the pin 25 strip, which connects the I/V resistor and output coupling capacitor. The DAC will function without this capacitor, since power supply decoupling capacitors are contained in the module. The capacitor will affect the sound quality of the DAC.
Soldering the electrolytic capacitor should be one of the final assembly steps.
If you have removed the pins from the module and are soldering parts directly to the module, the positive of the cap solders to hole 28 of the module, and the negative is now able to solder to the outermost hole of strip 27.
Be sure to check the polarity of the capacitor. Ground connects to green and positive connects to red. Irreparable damage to the capacitor will occur if this is reversed.
You can press fit different electrolytic capacitor values, and determine the value that sounds best to you. If you like the sound of a lot of capacitance, you can also add capacitors in parallel to the +5V/GND strip, if space permits. If the +5V/GND strips are covered by output coupling caps, there is also open space in the center of the board, between the module and RCAs, that can accommodate a very large amount of capacitance. You will need to solder jumper wires to the +5V and GND strips.
