Self noise in 414 channel


New member

My 414 mki (original owner!) is generally noisier than it used to be. Particularly, one channel is quite noisy on playback even if I have nothing plugged in. It's similar to white noise and I can eliminate it by turning down the channel's volume. It does get worse when I turn the trim fader up from Line to Mic, so it's not like it's stuck at Mic or something.

What kind of culprits should I look for here? Any caps that I should replace (even if I don't see any bulging)?

The trim and volume faders are a bit sticky-- could the noise come from dust? I have used Deoxit D100 from the surface but would need to fully disassemble the faders to really get the dust out.
If the noise is constant, i.e. does not come and go as you move pots or switches it is likely a transistor or an op amp. You can often pin it down with a can of freezer spray (NOT the stuff plumbers use!). Blast transistor or chip for a second and see if noise reduces. Then put a finger on it to warm it up and positively identify the culprit.

Sometimes a resistor can go noisy but this really only happens in old guitar valve amps that use those crappy Carbon Comp' resistors. Modern Metal Films last forever.