NV112 problem

Jerry Bull · Post by **Jerry Bull** » 3 Mar 2017 7:16 pm

One of my 112's has an issue that's been around for a few yrs now. When the amp is first turned on it sounds good. Then after about 30 seconds it develops a hum. I've already sent it to Peavey but couldn't tell any difference when I got it back. The problem is isolated to the amp for sure. I've even carried it to another off site location and plugged it in and still the same problem is still there (no cables or instrument)
Could this be power supply related? As a last resort I'll swap power supply from other amp to confirm. Any advice would be greatly appreciated.

Scott Duckworth · Post by **Scott Duckworth** » 4 Mar 2017 3:36 am

Well, if this happens in only one physical location, and number of things could be going on. Two that come to mind are an outlet wired wrong, missing a ground (or maybe a goofy extension cord) or florescent lights or some other transformer operated device causing the hum.

I had a 112 that, in my church, the XLR Line Out never worked, and I know for sure the church connections were wired right because I did them myself.

Bill Ferguson · Post by **Bill Ferguson** » 4 Mar 2017 5:15 am

If you are using the internal reverb of the NV112, it has an inherent hum.
Every one of my 5 NV112's have this and it is deemed acceptable by electronic standards.

Turn the reverb off and see if it goes away. Mine does.

Jack Stoner · Post by **Jack Stoner** » 4 Mar 2017 6:20 am

As its initially OK and then starts the hum after about 30 seconds, that says its probably not the reverb hum as it would be present immediately.

I had a hum problem in the NV112 I had. Turned out to be flakey (intermittent) connection on one of the internal Molex connectors for the power supply. Remove the chassis (leave the speaker connected) and power on, CAREFULLY (there is voltage there so careful is the word) wiggle the Molex connectors and see if it stops/starts. Spraying both the male and female Molex pins with contact cleaner fixed my problem.

I don't think it would be easy (or wise) to try and swap power supplies between the two. You may wind up with both inoperative.

Jerry Bull · Post by **Jerry Bull** » 4 Mar 2017 7:12 am

Strangely enough, I can take both amps side by side, with nothing plugged in to either one and with reverb tanks unhooked and the bad amp always develops this "hum/buzz" after it warms up. As an experiment, I carried this silly thing around to various gigs over the course of about 6 months just to try to isolate it to an outside voltage issue but determined it's definitely in the amp somewhere.
Jack, I'll try your suggestions next. Thanks