Control Unit Repair Procedure - Panasonic SAHT730 - DVD THEATER RECEIVER Technical Manual

Control unit repair Procedure

To perform the following steps, you need to locate the jumper wires and identify
which jumpers carry what shutdown signals to the IC2018 microprocessor (using
figure 9). The purpose of the jumpers is found in the concept diagram figure 10.
Procedure:
1. First prove the problem is in the control unit by cutting the W2344 jumper on the
top of the board (at location grid K7). Measure the voltage at W2156 / G8 at
power on. This cut disconnects most of the control unit's protection into micro
IC2018.
• If the 9Vdc is present before shutdown, the problem is in the subwoofer
assembly and not in the control unit. Reconnect the jumper and go to the repair
information on the subwoofer (page 12).
• If the 9Vdc is present, and the unit does not shutdown the problem is in the
control unit. Shut off the unit and proceed to step 2.
• If the 9Vdc is absent, the problem is in the control unit. Refer to figures 9 and
10. Either the M9V source (Q2803) is missing or the 9Vdc is loaded down
(reduced).
Cut jumpers W2413 and W2154 one at a time to determine which load causes
the reduced or missing voltage. If cutting both jumpers does not restore the
missing 9V, the M+9V source is bad.
2. If the unit does not shutdown because you have compromised the protection
circuit (e.g. cut W2344), only keep the unit on to measure a test voltage. Monitor
the various voltages at these jumpers to determine which is incorrect: [The
jumper's grid location follows the "W" jumper number.]
W2550 / M7 = SW 5Vdc
W2417 / K8 = + 7Vdc
W2340 / I7 = - 7Vdc
W2235 / K9 = 0Vdc
W2427 / J8 = 9Vdc
3. Except for the K9 (0V) measurement, if any of the voltages listed above is
missing, cut the (load) jumper and measure each of its ends. If the voltage is now
present at one end after the cut, its load is shorted. Trace down and troubleshoot the
Use the "Protect Paths to Micro IC2018" diagram (figure 9) to make sure that the
jumper is the load jumper that bridges the load and the source voltage before cutting.
SA-HT730 / SAHT930
+
Inv Q2818
14
IC2018
Micro