Subwoofer Unit Repair (Sb-Wa730 / Sa-Wa930); Subwoofer Repair Strategy - Start By Isolaating The Problem - Panasonic SAHT730 - DVD THEATER RECEIVER Technical Manual

Subwoofer Unit Repair (SB-WA730 / SA-WA930)

Overview - Refer to figure 11. The SC-HT930 consists of a Subwoofer and Control
unit. The units are connected by a 25 pin round umbilical cord that carries power
from the Subwoofer to the control unit and audio from the control unit back to the
subwoofer. When connected together and plugged in to AC, the Subwoofer provides
standby (SYS6V) voltage to the micro in the control unit. The SC-HT730 model is
similar but has less front channel wattage. That model does not have a Subwoofer
front Amp Board. Its front channel power amplifier is part of IC501 in the subwoofer's
Power Board.
Figure 11 -
Protection - Refer to figure 11. The protection monitoring circuitry in both of the
subwoofer (left) and control unit (right) feed the microprocessor IC2018 in the control
unit. If shutdown is triggered, the micro via the 25 pin umbilical cable opens the
subwoofer AC relay power relay, shutting off the power for both the control &
subwoofer [but standby voltage (SYS 6V) is still present]. Error code F61 may be
displayed just before power is lost.
In the subwoofer, the lines monitored for shutdown are:
• Speaker Balance – All 6 channels to the speaker must average 0Vdc +0.6Vdc
with or without audio or the unit will shut down.
• + 9Vdc balance – Both the positive and negative 9V power supplies must be
within 1.2V of each other or the unit will shut down.
• + 9Vdc loss – Missing 9V or excessive 9V load that brings the 9V line below
5Vdc will shut down the unit.
Subwoofer Repair Strategy – Start by isolating the problem
SA-HT730 / SAHT930
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