NAD 2700 Amp, goes into protection >25% volume

[almstsobur]

Hey all, I’ve been searching the web and this site for some info on this, but I can’t find anything that seems to depict my exact problem. I have a NAD 2700THX Amp that goes into protection when I turn up the volume on my pre-amp past about 25%. It sounds fine, channels play; all settings and connections are fine until I turn up the volume. I can also turn the volume back down after its hit protection and it comes right back and plays normal at lower levels.

Can anyone point me in the right direction on where to start troubleshooting this? I have the service manual, but I am at a loss about where and how to start testing things. I have opened it up; I don’t see any bad connections, popped caps, or anything that looks out of the ordinary. I have a second functional one of these amps as well; I have not tried swapping at part yet because again I’m not really sure where to start. My tools right now are pretty much limited to a multi-meter and soldering iron.

I appreciate any assistance, also if there are any guru’s in the N. California (Stockton, Sacramento) area that might be willing to assist I would be willing to pay.


Thank You,

[almstsobur]

So, when I got home tonight I cracked open a liquid therapy (Beer) and decided to open up both of my amps, the broken one and the working one to compare and contrast a bit. A little background, I bought both amps used, including the non-working one in "non-working" condition, the current problem was described before the purchase, but the person I bought it from claimed to have no idea what the problem was. Both of the Amps are the exact same model NAD 2700THX, about 400 digits in the serial number separate the 2 amps.

Attached are come pics, where all 4 of the C300's caps are missing on the broken amp. I have not a clue what these caps do, and I am not sure if this was a design change, I am hoping from the pic's and the attached screenshot of the service manual some one can tell me if this could be related to the problem.

Thanks again.

[almstsobur]

One more set of pics, other side.