Troubleshooting - Bose 3-2-1GS Series II Service Manual

Console Troubleshooting Tips
Symptom
No power
Console does not initialize
properly
VFD does not display
No remote response
Analog audio input or
AM/FM audio garbled or
fades away after playing
for a while
Console keys won't
function
No optical audio
Audio drop out at high
volume
Reduced AM tuner
performance
Channel coupling at the
Zone input
Cannot read the bass
module's software version
Video has incorrect color
balance (chrominance)
Analog signal coupling
during DVD/CD playback
Distorted video/audio
No analog or AM/FM
audio, but digital audio is
normal.
Check for...
- Check input line cord and/or system cable connected properly.
- Check U2 and U17.
- Check that the DVD eject pin is properly aligned with the inner
bezel plastics. The DVD eject pin loop should fit into the recess
in the inner bezel plastics. If this pin is installed with the loop
vertical instead of horizontal, it will not fit into the recess and
will cause the DVD drawer to not close properly, putting the
DVD drive and console electronics into a confused state.
- Ensure that the DVD drive ATAPI cable and power cable are
properly seated.
- Check that the ribbon cable from the VFD to J6500 is properly
seated.
- Check transistor Q6503. Replace if defective.
- Check transistor Q1 (270841-001) on the IR board. Replace if
defective.
- Check that the IR board ribbon cable is properly seated.
- Check that the ribbon cable from the button board to the main
PCB at J6700 is properly seated.
- Check the software revision level. Update with the most recent
software version.
- Check the DAC IC U9200 DC offset level at the left and right
analog outputs.
- Check that the ribbon cable from the button board to the main
PCB at J6700 is properly seated.
- Check the optical SPDIF input connector J8000 for bent legs
on the bottom of the PCB.
- Check resistors R455 and R450 on the bass module
Amplifier/DSP PCB.
- Ensure that there is no hot-melt or other debris on the thermal
tab of the power amplifier ICs U150, U250 and U350 located
on the bass module Amplifier/DSP PCB.
- Check the 20.00 MHz crystal Y9640.
- Ensure that the barrel of the AM connector is not touching the
enclosure's base, which is conductive near the AM connector.
- Ensure that there is a good ground connection between the
cable and J202.
- Check R4201.
- Check 27.00 MHz crystal Y7000 and ensure that is within
37ppm.
- Check Q9100, Q9101 and Q9102.
- Check and replace digital video processor IC U7003.
- Check U4000.
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