Bose T5 Service Manual page 28

Symptom
No Output from
Microphone
Low microphone
output, intermittent
microphone
transmissions or
difficult to break
intercom squelch.
No Active Noise
Reduction (ANR) or
Reduced ANR
Audio from only one
source on Dual
Comm versions
Unpowered (Fail
Safe) Mode Not
Working When Not
Connected to Vehicle
Troubleshooting

Check for damage or contamination, i.e. rust, chewing tobacco,
debris. If mic is damaged or contaminated, replace it.

Check microphone connection to the headset. Ensure wiring harness
is not damaged and that the connector pins are not bent and
connector is properly seated.

Replace microphone with a known good one. Retest. If okay, replace
original microphone.

Make sure unit is turned on.

Check power. Battery or external? ANR switch only controls battery
powered ANR, not external (vehicle) powered. ANR will be on all the
time when connected to vehicle power.

Check for defective cables, cracking of strain reliefs and/or bent pins.
Replace cable as needed.

Check position of Talk-Through (TT) rotary switch - The talk-through
function allows external audio from the microphone to be fed through
the headset without removing it, i.e. to speak to someone in the same
vehicle. Leaving TT on will reduce ANR and should only be used
when needed. Talk-through switch must be OFF for ANR to work
completely.

Check for low battery if not vehicle powered. There is no LED on the
product to allow monitoring of the battery power level. Low battery
when in ANR or TT mode will cause intermittent operation or clicking
every few seconds to indicate weak batteries. Unit will continue to
operate in this mode for some time before the batteries fail entirely
and the unit operation reverts to fail-safe operation mode. ANR will
be intermittent with clicking every few seconds.

Check all cables, earcups and control module for damage. Check for
damage or blockage of the microphone ports on the earcups. These
microphones are used to pick up noise in the environment in order to
cancel it. Damage or blockage will affect ANR functionality.

Check for defective switches on control module. If inoperative,
replace control module.

Connect a known good control module and cable. Connect to a
known good source and retest. If still bad ANR, replace earcups.

Port 1 is primary source and Port 2 is the secondary source. Ensure
you have correct cables and connections for the desired mode of
operation. Refer to the Dual Comm Mode of Operation table listed
previously in this manual.

Check all cables and control module for damage.

Connect known good cables from the control module to the radio.
Retest. If okay, replace original cable.

Connect known good control module. If okay, replace control module.

Ensure control module switches are not intermittent. If bad, replace
control module.

Single Comm – Headset Not capable of operating in unpowered fail-
safe mode when in dismounted mode. Will allow for ANR and TT
when operating dismounted on battery power.
Verification/Solution
28