NAD 3240PE Crackle sound from left channel
I'm hoping there might be someone out there who has experienced this and successfully diagnosed and repaired the fault.
Here's the scenario:
The amplifier works on both channels, but there is intermittent crackle on the left channel. It is not the speakers as the fault is present when listening on headphones.
With no sound source playing, the noise is clearly audible, it is visible on the scope as 100 - 200mV of DC with varying amounts of ac peaks. I can adjust out most of the dc by adjusting the centre voltage on VR401, but the output does not remain stable and noise free like the right channel.
I have checked all the electrolytics in the signal path and they all seem ok, and I am assuming the PSU is ok as only one channel is affected.
The noise is not coming from the pre-amp as it is still present with the pre-amp disconnected.
I'd appreciate any comments or suggestions from anyone who knows the characteristics and faults common with these amps.