I have a NAD 7100 receiver that is weak in the right channel. It is a definitely a pre-amp issue, and I have replaced all the electro caps in the signal path, but the problem still remains. I have adjusted the channel balance trimpot as per the service manual, but while that makes the channels equal at full volume, the difference remains at normal levels. Help!!!
You would have to go to the next devices in the circuit after the trim pot, MA. Unfortunately, I bet thats a discrete device on a pcb. As the problem is not linear, it cannot be attenuated in one channel alone.
In reply to Michael Wodek: I determined it was a pre-amp issue by 1 putting Left pre-amp out into BOTH power amp Left and Right and seeing output was equal, and 2 putting preamp L out into power R and preamp R out into power L and noting the mis-balance had swapped channels. I set the preamp channel balance as per the service manual by setting volume to max and putting 100 mV 1kHz into L and R CD input and adjusting trimpot for equal preamp out (using oscilloscope). However even after that adjustment, the channels are still unbalanced. At normal listening levels the balance control has to be at 3 o'clock for equal output. Observing the preamp outputs with the scope, they gradually become equal as the volume increases.
Here are the relevant sections of the circuit diagram. Note that I replaced all the signal path electros on the pre-amp board, but NOT in the tone control section which is on the main amp board. Sorry about image quality, but the 600x600 <100k rule is pretty limiting. ---- relevant section frompre amp board ---- ---- tone control on main board ---------------
