My old faithful NV112 died

Lynn Kasdorf · Post by **Lynn Kasdorf** » 5 Jun 2022 7:38 am

I played an outdoor festival yesterday and when I plugged in my amp, I was greeted with a loud, trebly 60hz buzz that throbbed. I actually could play the steel and get a sound out of it, but it was mixed with a weird, changing buzz and crackling.

I went through the house PA for the gig. Not ideal, but it worked.

I had used this amp just a couple days before with no issues. It did spend a little time in my hot car, but not a lot- I've learned to not subject my gear to summer car-oven heat. But that is all I can think of.

I'll find out shortly when I put it on the bench, but I'm guessing that a filter cap gave up.

I wonder if class D amps are more tolerant of heat? I guess it comes down to the quality of the caps employed.

Post by **Dave Mudgett** » 5 Jun 2022 7:51 am

My NV 112 did the same thing a few years ago. I opened it up and found a solder joint at the electrolytic power supply filter caps had broken loose. Re-soldered that joint and touched up the other solder joints in the vicinity, no problems since. Hopefully it's that simple for you.

Clyde Mattocks · Post by **Clyde Mattocks** » 5 Jun 2022 9:13 am

Similar problem, same sounds. Turns out it wasn't the amp at all. I had a Lexicon digital reverb in front and never changed the settings. Once I got it home and found the amp worked fine by itself, I found moving the knobs on the reverb produced the same static. Now I rotate those knobs regularly.

Lynn Kasdorf · Post by **Lynn Kasdorf** » 6 Jun 2022 6:06 pm

Dave Mudgett wrote:My NV 112 did the same thing a few years ago. I opened it up and found a solder joint at the electrolytic power supply filter caps had broken loose. Re-soldered that joint and touched up the other solder joints in the vicinity, no problems since. Hopefully it's that simple for you.

Dave- you nailed the diagnosis exactly! This was the first thing I was going to look for anyway, but it is funny that it was exactly what you said.

One of the cap's connections had cracked loose. I resoldered all the filter caps and used hot melt glue to adhere them to the board. I'm happy it was this easy.

Post by **Dave Mudgett** » 6 Jun 2022 7:58 pm

Glad to hear it was simple. I think there is a bit of an issue with the way that solder joint holds together, and it may relate to caps flying loose. And yes, we used hot melt glue to stick the caps to the board.

I've had to glue caps or preamp lead wires on several relatively recent production amps, including one high-end boutique amp. On that latter one, the leads to the preamp tubes were flying in such a way that a bad parasitic oscillation was occuring. The glue was used to tie them down into a position where that didn't happen.

Nothing like the old push-back cloth wire that has memory - i.e., retains whatever bends you put in it so you can route it however you please and it will stay put.