ParkingLotLust
Member
Hey all,
I've got a Yamaha RX-496 receiver that's acting funny.
Here's a video of my scope connected to the Right "A" speaker. Notice the noise that starts immediately after powering on:
This noise occurs with the input to the amp's "power board" disconnected (R + L signals). I clipped the R & L lines coming into the "power board" (p.38 in PDF) to attempt to isolate the problem - since it is still happening I assume the problem is on the "power board"
The problem does not occur on the L channel.
Probing the R input on the "power board" (the wires I clipped) I see a similar waveform (but much lower amplitude). I also see a similar waveform on the emitters of the power transistors. Amp power rails appear normal (53v/-53v).
I've attached the repair manual including schematic. Any ideas would be appreciated!
I've got a Yamaha RX-496 receiver that's acting funny.
Here's a video of my scope connected to the Right "A" speaker. Notice the noise that starts immediately after powering on:
This noise occurs with the input to the amp's "power board" disconnected (R + L signals). I clipped the R & L lines coming into the "power board" (p.38 in PDF) to attempt to isolate the problem - since it is still happening I assume the problem is on the "power board"
The problem does not occur on the L channel.
Probing the R input on the "power board" (the wires I clipped) I see a similar waveform (but much lower amplitude). I also see a similar waveform on the emitters of the power transistors. Amp power rails appear normal (53v/-53v).
I've attached the repair manual including schematic. Any ideas would be appreciated!