[Jacques]

So I have a 3020 NAD stereo amplifier driving a pair of B&W 686 S2 speakers, I love the setup to bits. Problem is some of the dials on the NAD possibly have dirty contacts as they make a create a crackling feedback sound when turned. The volume one is the most suspect...

Is there any way to clean them properly?

[BrainStorm]

Are you wanting to just de-energize, pull knobs, and spray? Or do you want to really get into things? IMHO, either is proper, but a case-off service will last far longer. I use CRC contact cleaner (Wal-Mart), and Formula77 lube (hard to find, pricey) and, by either method, get wonderful results from just spraying (liberally) contact cleaner into the shaft and/or fat sides of the switch while turning the shaft stop-to-stop. Let dry, then do the same (sparingly) with the lube. As long as there aren't damaged spots on the contactor surfaces, it's really just a mater of removing any micro-corrosion and dust from those surfaces. I have manuals and shemas if you want any.

BTW, I have several NAD amps, and a tuner/amp (7600 + 3x 904s) and they are lovely to listen to. I have (4x) Miller & Kreisel smaller speakers and a pair of Quantum III (prior to becoming Infinity). All fantastic audiophile level stuff.

[Jacques]

Are you wanting to just de-energize, pull knobs, and spray? Or do you want to really get into things? IMHO, either is proper, but a case-off service will last far longer. I use CRC contact cleaner (Wal-Mart), and Formula77 lube (hard to find, pricey) and, by either method, get wonderful results from just spraying (liberally) contact cleaner into the shaft and/or fat sides of the switch while turning the shaft stop-to-stop. Let dry, then do the same (sparingly) with the lube. As long as there aren't damaged spots on the contactor surfaces, it's really just a mater of removing any micro-corrosion and dust from those surfaces. I have manuals and shemas if you want any.

BTW, I have several NAD amps, and a tuner/amp (7600 + 3x 904s) and they are lovely to listen to. I have (4x) Miller & Kreisel smaller speakers and a pair of Quantum III (prior to becoming Infinity). All fantastic audiophile level stuff.

Just a pull and clean is what I'm after, if possible. I've already repaired a few bits inside (one being a cracked fuse holder) so the amp is clean and otherwise in good order inside. But if it means I can get into the knobs a bit better with the case off then that's what I'll do. 

I'll look out for the contact cleaner and the lube here in the UK, probably will be available from somewhere like RS components. If you could send through the schemas (I have the manual) it would be appreciated for future use. 

I have contemplated recapping the amp but I want to leave the original parts for as long as possible. It takes a good 10mins from a cold power on to achieve full depth of sound. The first 10 mins lacks some bass and clarity, almost like having a light low pass filter on, after that it cleans up well and gives very good crisp response.

[BrainStorm]

I'll look out for the contact cleaner and the lube here in the UK, probably will be available from somewhere like RS components.

Contact cleaner is contact cleaner, for the most part. I like the CRC because it's only $4/can, and pretty much available everywhere here. (AutoZone, O'Reilley's, Wal-Mart, etc.) What you REALLY must pay attention to is the lube. IF you can actually find 'rotary switch cleaner and lube', get it. It's by far the safest and most effective, but I've had problems even finding it online. Everything is bubble switches and touch these days, and damn it, it just makes me feel old!
The main thing on the lube is that it MUST NOT contain any solvents. WD-40 and the like contain DMSO, which will dissolve the metal contactor traces eventually, and the lube will leech that metal substance, and progressively turn to into goo while also ruining the switch. The Formula70 (not 77, my mistake) is about $9/can, but well worth it. It's also hard to find, but component suppliers usually have electronics safe lubes like this. The ECG is $14/can, and it's for washing boards after SMD rework/repair. It's made for removing flux residue without damaging teensy little SMD parts, so I use it sparingly for really tough cases of dirty switch syndrome, such as built up cigarette smoke. (NASTY!!!) The ECG/board wash also evaporates extremely fast, not allowing much time to rotate the switch to scrape the crap off the contact surfaces.

Method for case on: UNPLUG! and let sit for a while to lose static energy, pull the knobs, use the red tube to spray right at, and straight in at the base of the shaft while turning the shaft rapidly back and forth. After the contact cleaner has had time to dry, do the same with the lube, except be sparing with the spray as too much may get it all over the inside of the unit. Just a shot and keep turning, keep turning, keep turning, then repeat. The lube will work it's way down that shaft, even horizontally, but if you can tilt the unit up it will help.

Best method, case off: Paper towel under switch body to catch drips, spray into the (usually) open sides of the rotary switch while turning the knob, stop-to-stop. After dry time, a very quick shot of lube the same way, maybe from each side of the switch. Keep rotating that sucker until the lube gets distributed around the entire contact circuit. Afterwards, I wipe the outside of the switch body with a paper towel dampened with contact cleaner to avoid attracting dust. Reassemble the unit, connect phono player, place Pink Floyd: Dark Side Of The Moon vinyl, rock on.

If you could send through the schemas (I have the manual) it would be appreciated for future use.

NAD 3020 Service Manual & Schematics

https://mega.nz/#!v98SHKxR!MrE_vyoDJKrDb...EdJJbIgOBI

[micrex22]

The main thing on the lube is that it MUST NOT contain any solvents. WD-40 and the like contain DMSO, which will dissolve the metal contactor traces eventually, and the lube will leech that metal substance, and progressively turn to into goo while also ruining the switch. The Formula70 (not 77, my mistake) is about $9/can, but well worth it. It's also hard to find, but component suppliers usually have electronics safe lubes like this. The ECG is $14/can, and it's for washing boards after SMD rework/repair. It's made for removing flux residue without damaging teensy little SMD parts, so I use it sparingly for really tough cases of dirty switch syndrome, such as built up cigarette smoke. (NASTY!!!) The ECG/board wash also evaporates extremely fast, not allowing much time to rotate the switch to scrape the crap off the contact surfaces.

Yeah I remember people who 'oiled' ball-bearing fans with WD-40 and broke them.

Well this is good timing because I need to get the JUNO-60's volume knob desperately addressed since it's scratchy, along with some of the Jupiter-4's sliders. Guess I'm ordering Formula70 online, I highly doubt any stores will carry it; all of this stuff is history--everyone is just in to disposable electronics and cellphones.

The Polymoog could use a bit of lube, too <-- never thought I'd say that sentence in my life.

[Jacques]

Well I spent 45 mins yesterday with the cover off, desoldered the switch (couldn't really get to the POT any other way) and took the whole volume POT switch apart.

There wasn't a huge amount of dust in there, mostly some carbon powder from the contacts. The contact strips were in very good condition so I cleaned them with some 90% isopropyl alcohol and reassembled. Worked a charm, no more scratching noises!

Thanks for the schematic!

[matyas]

Afraid I can’t help too much with that particular issue, but nice to see a fellow audiophile here. I worked as audio engineer for years and I’m into domestic hifi as well as pro audio. Home studio has B&W 602s with Parasound amplification and the living room is vintage Advent with Rotel (Oppo CD/DVD/SACD and Denon turntable with Grado cartridge.)