Initial check
Build and test your γ1 first before checking the γ2.
Be sure that your γ1 passes all tests described in the
γ1 website
"Initial Check" section before proceeding here.
γ2 board test points:
- Check to make sure all jumpers are set correctly for all the options
that you're building, and that you have populated the correct
combination of parts for your chosen configuration. See the
Parts list section. Inspect your board
for solder bridges or possible cold joints using a magnifier.
Reflow any joints if in doubt, and measure its connectivity with
your multimeter in Ohms mode.
- Plug the γ2 board into the γ1
board, making sure that all the header pins are seated properly into
their corresponding receptacles.
- Apply power to the circuit, either by connecting the γ1 to
the USB port of your computer, or by plugging in a regulated
5V DC power adapter into γ1's DC input jack.
- Using your multimeter, measure the DC voltages at the +5V, +4.5V and
+3.3V test points, relative to GND. You'll need to use the bottom
side of the board for these measurements, because there is no access
to the top side when the γ1 and γ2 boards are mated.
The +4.5V test points should read 4.5V if your U1 is a LP2985A-4.5,
or 4.75V if you used a TPS793475. If you don't get the correct
voltages, remove power and check your work carefully.
- Turn your amplifier's volume control to minimum, connect the
γ2 analog output (RCA jacks or 3.5mm stereo mini jack on the
rear side of the board) to the line input of your amplifier.
- Connect a digital source (USB, coaxial or optical) to your γ1
board, and set the input selector switch (if applicable).
- Play some music and turn up the volume on your amplifier. If
all is well, you should hear the music.
If you passed all the steps above, then proceed to the "Preparing
the case" heading in the instructions
section.
In case of difficulty
Most of the problems with the γ1 and γ2 are related
to solder joints. If your γ2 does not work, disconnect the
board and check all the solder joints again.
Driving headphones from γ2
Since γ2 has no volume control, if you use it to drive
headphones directly, you must use the software volume control
on your computer. If you're using a CD player or digital media
player, use its built-in digital volume control. If your player
has no such control, then it would likely be too loud. The solution
is to use a headphone amplifier with a volume control.
Notes
- If a SMD chip becomes defective and must be replaced, and if
you don't have specialized reworking equipment, the recommended
method is to use
Chip Quik® SMD removal kit.
Their website has instructions on how to use it. Chip Quik is
available directly from the manufacturer, as well as from
Digi-Key (part number SMD1-ND).
If you don't have Chip Quik, use a sharp knife to cut the leads
off the bad chip near the chip body. Take care not to
score the board. Then, remove the chip from the board.
Heat each solder pad with your soldering iron and scrape away
the residual pin. Then, remove any excess solder using your
iron and a desoldering braid. Be careful with the iron so
you don't melt any surrounding parts. Also, don't heat the
board for prolonged periods of time to avoid delamination.
Soldering in the new chip will be just like the first time.
You need to be careful not to touch the other parts already in
place with your iron.
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