Author Topic: Yamaha RX-V765 Amplifier Issue  (Read 247 times)

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Offline irobotTopic starter

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Yamaha RX-V765 Amplifier Issue
« on: October 03, 2024, 10:49:11 pm »
Yamaha RX-V765 7.1 Channel Home Theater Receiver

After replacing Q1055A and Q1055C (outputs) and emitter resistor R1153:

-1.5V DC on speaker output, SL channel. Although the unit works, it should be near zero. Not comfortable leaving it this way.

B+ and B- are where they should be at all points.

I'm at a loss because I've checked every component and taken other measurements using good channels as reference.

Voltages on other channels are just about spot on to what schema shows.

I replaced Q1041, Q1048, C1034 with no change.

Notes: Q1020, Q1027, Q1034 are for bias. Q1062 is a tap-off point for protect signal. Q1027 is physically attached to heatsink as temperature "sensor".

UPDATE 10/04/2024: Fixed. Replaced Q1011 and Q1012. Although checked out OK in and out of circuit, these must have been breaking down with power applied.
« Last Edit: October 04, 2024, 10:42:58 pm by irobot »
 

Offline David_AVD

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Re: Yamaha RX-V765 Amplifier Issue
« Reply #1 on: October 04, 2024, 02:27:01 am »
There will likely be a dead transistor or resistor somewhere just before the output transistors.
 

Offline suntime

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Re: Yamaha RX-V765 Amplifier Issue
« Reply #2 on: October 04, 2024, 09:16:58 pm »
Hi,

Check Q1020 & Q1011.
 


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