DC POWER INPUT AND DISTRIBUTION. Continued
Power Distribution in Vehicular Amplifier-Adapter (WA), AM-7239 Series. The 22 to 32 V dc from
J5, pin B, of the MB, enters the VAA through P1, pin B. P1, pin B is connected to CB1, which provides
over-current protection for the power supply. In the AM-7239 version of VAA, a shorting bar is used on
TB2 to bypass the contacts of relay K1 for LOCAL power control. The shorting bar is removed for
REMOTE power control. In the AM-7239A, a shorting jumper is moved for LOCAL or REMOTE
operation. In the AM-7239B,C,D and E, a switch is used for LOCAL or REMOTE operation.
DS1 will light at the AM-7239 if power is present. DS1 will light at AM-7239A if power is present at output
contact of relay K1. DS1 will light at AM-7239B,C, and E if power is present on 13 V dc line.
In the AM-7239E, transient protection is provided by the Transient Protect CCA (A3A1). The transient
protection circuit controls the gates of parallel field effect transistors (FET) Q7, Q8 which are in series
between the power input and the input to power supply Al.
1 - 1 0