A friend asked me to fix his keyboard amp. 50 watt solid state combo, 4 inputs. Loud crackling noise, kind of random. I'm suspecting a failing semiconductor. All the noise is coming from Channel 1. Long story short, Channel 1 has a phantom power option, and with the phantom power switch in the off position the switch is leaking voltage into the front of Channel 1. A shot of contact cleaner and all is well. Had a similar problem with a Peavey PA head. With the channel volumes at zero the channels still output sound. Dirty level pots that had significant resistance even when on zero. More contact cleaner and now all the channels go to zero and cut off the input. I've had loss of signal in pedal chains and rack systems that cleared when the input and output jacks were cleaned. Moral of the story is keep a good quality contact cleaner on hand! It's not just for crackling pots anymore And some problems are simpler than they appear.
I have had problems with dirty effects loop contacts twice now on different amps. A little contact cleaner spray on a Qtip and 1/4" plug was all it took to cure the problem. It made a very big difference.
This also (obviously, but often overlooked) applies to pedals! That pedal you have had for years, when is the last time you cleaned the signal contact points? They operate only on pressure, and current is flowing through them all the time when you play...when was the last time you opened up a pedal and looked closely at the jacks? On the other hand, I am not sure at all what to use to clean them. Contact cleaner that leaves a residue of oil can't be good, what do you use to clean them?
Caig Labs make great products. I've been using Deoxit with excellent results. It's a cleaner and contact conditioner.
+1 my carvin ag100D amp just kinda fitzed and crapped out on me .. none of the 3 inputs produced any sound, but if i plugged a line level source into the effects return, it worked (except the master volume didnt control anything) i took the chassis out and blasted the input jacks, pots, output jacks, and all the circuit boards with radio shack cleaner darn thing fired up and works fine .. saved me the $145 (+shipping) repair/overhaul fee that carvin wanted t4d
I was experiencing some intermittent power drops...like one of my power tubes was cutting out. Did a search for this and noticed someone suggested spraying the tube prongs with WD-40 and working in into the socket to improve contact. It worked! Saved me some bucks since I was looking at taking it to get it fixed. So it looks like I had some dirty contact surfaces in one of my power tube sockets.
I had an 1983 Marshall JCM800 with an effects loop that I rarely, if ever, used. Occasionally the contacts of the send/return jacks of the loop would corrode and loose conductivity. I found this out the expensive way, contacts in jacks and switches need to be cleaned every couple decades for continued use. Dirt, moisture and cig smoke can ruin anything if left un-attended. The severe loss of use caused by lack of simple maintenance is expensive, get some contact cleaner and wire brushes and run a male plug out of the jacks and exercise switches to keep them healthy.
