TECHNICAL BULLETIN
RTS-TB-030 25-July-2014
AIO-16 Audio Port Noise Susceptibility
Issue Severity:
Product(s) Affected:
High:
URGENT – Immediate Action
Required
AIO-16s with manufacturing date codes
between June 2011 and August 2013 (approx.
1700 total cards)
Medium:
Bosch Security Systems,
Inc. strongly recommends you take
the action(s) described below.
Low:
Advisory
Notification Applies To:
Access Restrictions:
Technical Support (TSS)
Internal Distribution
ONLY
Repair (ASA)
No
Restrictions (Internal & External Distribution)
Sales (NSO / RSO)
1.0 Issue
It was recently discovered that a portion of manufacturing test was omitted on AIO-16s made at the Bosch
Zhuhai manufacturing facility during the time period from June 2011 through August 2013. A series of
calibration steps related to Common Mode Noise Rejection (CMRR) optimization were omitted from the
manufacturing process. The result is that cards manufactured during this period have unbalanced audio
inputs that can be more susceptible to noise on the incoming audio lines. This allows noise to pass through
the input receiver stages of the AIO-16 and be heard by customers. In low noise environments, this may not
be detectable. However, any installation with noise present on the incoming audio (due to equipment
grounding issues, for example) may detect audible noise on these channels.
In general, since none of the 16 channels on the AIO-16 were properly calibrated by manufacturing, any
audio input may be vulnerable to this condition.
2.0 Resolution / Corrective Actions
In order to address this issue, the common mode rejection must be manually tuned on each of the 16 input
channels of the AIO-16. This is done by adjusting a potentiometer on each input audio amplifier circuit.
Bosch recommends that this adjustment be performed by an authorized service technician.
