I/O Disclaimer; Table 9-2. Normal Operation Range And Esd Clamping Voltages - Motorola ASTRO XTL 5000 Basic Service Manual

Basic Troubleshooting: Introduction
Table 9-1. J2 Accessory Connector Signal and Voltage Descriptions (Continued)
Pin
21 RX FILT AUDIO Receive Filtered Audio
22 MONITOR
23 AUX MIC
24 SW B+
25 Ignition
26 SPKR-
9.1.2

I/O Disclaimer

Some of the signal lines on the J2 accessory connector
between 0- and 5-volt operation. It is obvious that improper connections to any electronic device
might result in damage. Some of the logic lines are limited to between 0 and 5 volts and other inputs
between 0 and 20 volts. The exception is the UARTA, which can tolerate up to ±15 V maximum. At
no time should any two (or more) outputs be connected together. Exceeding these input voltages or
output loads could result in electronic component failure. In most cases Zener diodes have been
added to protect against ESD.
Table 9-2 provides the normal operation range and ESD clamping voltages at accessory connector
J2. If a radio is suspected of failure due to improper connections, the table can be useful in diode-
continuity testing the accessory pins on the radio as a closed unit.

Table 9-2. Normal Operation Range and ESD Clamping Voltages

'%
3LQV
1 Ground
2 Bus +
3 Bus -
4 UARTA_TxD
6881096C73-O
Function
Out
Monitor overrides PL
Rear microphone input
Switched Battery Voltage This voltage is available when the radio is
Ignition Sense
Speaker -
)HPDOH
VROWDJH DW 3RUW -*
Description
This is a fixed level (independent of volume
level) received audio signal, including alert
tones. Flat or de-emphasis are programmed by
CPS. Output voltage is approximately 100
mVrms per 1kHz of deviation. The DC offset is
1.4V.
This output is used to detect when a rear
microphone accessory is taken 'off-hook', to
over-ride PL to alert the user to busy traffic
prior to transmitting.
This microphone signal is independent of the
microphone signal on the front microphone
connector. The nominal input level is 80mVrms
for 60% deviation when used for motorcycle,
but can also support 300 mVrms for future
APCO accessories. The DC impedance is 660
ohms and the AC impedance is 560 ohms.
switched on, at A+ levels.
Connecting this line to the ignition line of the
vehicle will allow radio turn-on via the on/off
button when the vehicle ignition is on.
Connecting this line to the car battery will allow
radio turn-on via the on/off button, regardless
of the vehicle ignition status.
Used along with SPKR+ to connect an external
speaker. The audio PA is a bridge amplifier
with a 3.2-ohm minimum impedance.
(Figure 9-1, on page
5HYHUVH %LDV
9ROWDJH DW 3RUW -**
0
0.7
0.7
High Z
9-3
9-1) are limited to
0.00
4.30
0.45
-9.20
June 11, 2003