STR-DN850
12
TROUBLESHOOTING
Flow of Repair (when sound is not outputted) (1/5)
NG
START
OK
OK
NG
NG
NG
NG
NG
NG
NG
OK
OK
OK
OK
OK
OK
NG
OK
OK
OK
NG
Check the surrounding circuit of power transistor (example: Q600 on the MAIN board) and the surrounding circuit of power amplifier circuit (example: FL on the MAIN board), and exchange the defective parts.
– Continued on page 13 –
Measure the power amplifier circuit (example: FL on the MAIN board) with a tester, and check the following things. 1. Check that between the power supply line and the ground does
not short-circuit.
2. Check that resistance is normal.
1. Check the R2140, R2141 Short or Open circuit? 2. Check Main Board +7 V Regulator.
Check that voltage of the follow pin 2.8 V. Digital Board: IC2100 Pin 99 (Fuse_Det)
Check that the “PROTECT” is not displayed on the fluorescent indicator tube.
Check that voltage of the follow pin 0.6 V. Digital Board: IC2100 Pin 67, 68
(Temp_Sensor_1&2)
Check that voltage of the following pin is 3.3 V. DIGITAL board: IC2100 pin 92 (PROTECT)
Check that the defect is not improved, even if you do the following works. 1. Short-circuit the both ends of the C2186 on the
DIGITAL board.
2. Perform the “SHIPMENT MODE” (refer to
page 21 on the original service manual).
Check the IC2100 on the DIGITAL board and the surrounding circuit, and exchange the defective parts.
Check the surrounding circuit, and exchange the defective parts.
Check that between the +59 V line/–59 V line (±B) and the ground does not short-circuit.
Check the surrounding circuit, and exchange the defective parts.
Measure the power transistor (example: Q600 on the MAIN board) with a tester, and check the following things. 1. Check that the circuit does not short-circuit. 2. Check that resistance is normal.
Check the surrounding circuit of power transistor (example: Q600 on the MAIN board) and the surrounding circuit of power amplifier IC (example: Power Amplifier on the MAIN board), and exchange the defective parts.
Check the R2115, R2134, C2164 and C2165 in Digital Board, Short to Gnd? TH251, TH252 in Main Board.
Check that the following fuses are not damaged. MAIN board: F912, F913 STANDBY board: F901
Check that the power transistor (example: Q600 on the MAIN board), the power and the surrounding circuit are not defect.
Check that the surrounding circuit of current detect (example: Q605 and Q604 on the MAIN board) is not defect.
Check the surrounding circuit of protector (example: Q320 on the MAIN board), and exchange the defective parts.
Summary of Contents for STR-DN850
Page 104: ...MEMO STR DN850 104 ...
