Jasper Dog
New Member
HI, I'm new here. This is my first post, so any advice or response is greatly appreciated. I am needing some direction on an NAD T 973 powere amplifier that isn't functioning correctly. It is a seven channel amp thats basically seven monoblocks sharing a power supply as I understand it. This one had a big surge or something hit it. One channel fried, two channels worked fine. The other four were and still are screwy. I took it to a reputable local repair shop. The fixed issues with the power supply. The amp card that fried we have set to the side for now. The other four are working, but they don't really have any high end sound at all. Just lower mid and low range. The technician has switched out these amp cards from one slot to the next and determined that the problem is in the amp cards themselves and as the two that are good work in any slot and the bad ones don't play good in any slot. We just both find it very strange that all four amp cards would be doing the exact same thing. We are really at a loss. he has tested them every way he can think of and says that all the voltages everywhere in the amp seem correct. He repaired some damage to the powere supply to get all the slots functioning correctly. He has performed a frequency sweep and says that the bad amp cards pass high frequencies during those albeit at about 60 percent of the volume of the cards that are totally good. He has adjusted the dc offset and bias to factory specs. So, we have no idea at this point how to proceed further. ANY advice would be greatly appreciated.