Saturday, January 16, 2016

DENON AVR-886 - AVR-2106 - AVR-786 - AVR-1906 - AVR-686 - AVR-1706 - AVR-486 - AVR-1506 - AVR-1306 Over heating Rectification - Recommended Change in the amplifier stage - Idle current adjustment - Factory reset -AV receiver Repair and service

                                                Category: AV Receiver Repair and Service 

Contents of this article 

  • Modification to the amplifier 
  • IDLE current Adjustment 
  • Initialization (Factory reset ) 

DENON AVR-886 - AVR-2106 - AVR-786 - AVR-1906 - AVR-686 - AVR-1706 - AVR-486 - AVR-1506 - AVR-1306

Description 
Preventing the Power Amplifier Circuit from breaking down.
Symptom:
The transistor that is used to compensate the temperature rise of the Power Transistor in the Output Stage is incapable of reacting to the rapid temperature rise. Because the temperature rise is not compensated properly the Power Amplifier Circuit may be damaged.
Solution:
Replace Transistor Q103 and resistor R101 upon repair and/or refurbishment of the unit. (The replacement of the capacitor and resistor is applicable to each channel (C, FL, FR, SL, SR, SBL and SBR).
Parts:
Ref
Description
Part Number
Q103 (C, FL, FR, SL, SR, SBL and SBR)
2SC3964, Transistor

00D 963 0280 107

R101 (C, FL, FR, SL, SR, SBL and SBR)
RD14B2E681JT, 680Ω Resistor
00D 241 2398 913
Modification Procedure:
1) Remove the Top Cover, and take out the Main P. W. Board from the unit.
2) Replace the Transistor and Resistor:
Remove Q103, 2SD947F Transistor (Q103FL, Q103FR, Q103C, Q103SL, Q103SR, Q103SBL and Q103SBR) and replace it with the 2SC3964 Transistor.
Note:There is no SBL and SBR on the models AVR-1306. Remove R101, 2.7kΩ resistor (R101FL, R101FR, R101C, R101SL, R101SR, R101SBL and R101SBR) and replace it with the 680Ω resistor.
Note: There is no SBL and SBR on the models AVR-1306.
3) Adjust the Idling Voltage: Turn the Power of the unit on. Then, after 10 minutes, adjust the Voltage to 2.0 mV ±0.5 mV. (Refer to the Service Manual for more details).
4) Reassemble the Main Unit and attach the Top Cover.
Idling Current
Required measurement equipment: DC Voltmeter
1. Preparation
(1) Avoid direct blow from an air conditioner or an electric fan, and adjust the unit at normal room temperature 15 °C ~ 30 °C (59 °F ~ 86 °F).
(2) Presetting
# POWER (Power source switch) OFF
# SPEAKER (Speaker terminal) No load
(Do not connect speaker, dummy resistor, etc.)
2. Adjustment
(1) Remove top cover and set VR101, VR102, VR103, VR104, VR105, on Amp. Unit, VR107SBL,107SBR on SURR.-BACK ch Amp. Unit at fully counterclockwise
( ) position.
(2) Connect DC Voltmeter to test points (FRONT-Lch:
TP104, FRONT-Rch: TP105, CENTER ch: TP103, SURROUND-Lch: TP101, SURROUND-Rch: TP102, SURROUND-BACK Lch: TP106, SURROUND-BACK Rch: TP107).
(3) Connect power cord to AC Line, and turn power switch
"ON".
(4) Presetting.
MASTER VOLUME : "---" counterclockwise ( min.)
MODE : 7CH STEREO
FUNCTION : CD
(5) Within 2 minutes after the power on, turn VR101 clockwise  to adjust the TEST POINT voltage to 1.5 mV ± 0.5 mV DC.
(6) After 10 minutes from the preset above, turn VR101 to set the voltage to 2.0 mV ± 0.5 mV DC.
(7) Adjust the Variable Resistors of other channels in the same way.
Initializing AV SURROUND RECEIVER
AV SURROUND RECEIVER initialization should be performed when the µcom, peripheral parts of µcom, and Digital P.W.B. are replaced.
1. Switch off the unit.
2. Hold the following SPEAKERS-A button and SPEAKERS-B button, and switch on the unit.
3. Check that the entire display is flashing with an interval of about 1 second, and release your fingers from the 2 buttons and the microprocessor will be initialized.