Servicing an old mixer. Need help with my shopping basket.

[Mushy Mushy]

I plan on completely overhauling my old Mackie 32:8 over the coming weeks as it hasn't really worked properly since I bought it 10 years ago. It's basically been a glorified table that entire time

So far I've ordered new ribbon cables for it (at a price I'd rather not repeat ). In addition I have the following:

- Compressed air for the decades of dust
- Goo Gone for the old labels on the scribble strip
- Mr Sheen (my favourite cleaning product) for the outer case

In terms of the knobs I was thinking about leaving them in a bucket of soapy water for a couple days. Is there a better option?

I'm mainly curious about what I should be buying for the internals though. Should I spray something into the faders? How should I dislodge caked on grit and dust? I'm sure at some point there will have been a drink spilled in there so how best to clean that?

Essentially I'm looking to have everything purchased and ready to hand so I can tackle the job in a couple sittings rather than leave it disassembled for months.

[MFXxx]

Hey mushy trust all good in your isolation containment facility!
For contact and fader cleaning also with general electronics I've always used Deoxit5. Good for connectors and contacts.
Then good ol isopropyl ipa 170 for general rail cleaning etc.
I'm in no way qualified so if anyone is aghast at what I'm using chime in.

[Mushy Mushy]

Hey mushy trust all good in your isolation containment facility!
For contact and fader cleaning also with general electronics I've always used Deoxit5. Good for connectors and contacts.
Then good ol isopropyl ipa 170 for general rail cleaning etc.
I'm in no way qualified so if anyone is aghast at what I'm using chime in.

Hey man, yes all good here thanks. Hope the same with you.

I’ll add ipa 170 to the basket however I’m not sure on deoxit. I know it’s the first suggestion in these types of threads but I’ve also read it’s the worst thing you can do in the long term as it leaves deposits. I need to look into this further I guess.

[MFXxx]

Yes all good here thanks bud.
Yes I think you may be corect re the detoxit. You should do some before, during and after photos..
Good luck.
I still have a Beringer MX8000 mixer in the garage needing some TLC.
It's on my to do list since 2009 haha.
One of the rails, channel 1, knocks the whole unit out not sure why. If I isolate and not use channel 1 all good.
I say one day haha. Retirement job me thinks.

[JCJR]

Mushy a couple of thangs maybe you already know/performed or whatever.

I may not be remembering correctly you could check on this-- I think at least in the earlier years Mackie used sealed-back rotary pots. If your pots are the sealed-back kind then they will be difficult to spray without drilling a hole in the sealed back or whatever. Maybe they are not sealed in your mixer. Maybe there are youtube guides or webpages of fellas who figured out the very bestest way to spray sealed pots. I didn't look lately.

You want non-residue cleaner to wash crud out of pots. Often old pots get stiff from old lubricant gelled up inside bearing surfaces. They wanted cheap pots to feel "luxurious" with some drag, like focusing a $2000 Nikon high-quality camera lens rather than some loose adjustment that moves effortless and rattles around. But after some years that carefully chosen semi-liquid, semi-gel lube in the new cheap pots would turn into barely movable petroleum goop and you almost need vise grips and a 3 foot lever to turn the knobs any more.

So when you use the non-residue spray to liquify that gunky mess so you can blow it out of the works and get free movement and hopefully non-scratchy-sounding movement, all that dissolved jurrasic gelled vaseline gets sprayed out and drips all over your circuit boards making a horrible mess of old now-re-liquified lube. So it needs some practice and strategy blowing out the gunk so that as little possible gets on the circuit boards to begin with, and of course whatever you miss needs cleaning off the boards, which is difficult and annoying because your cleaning swabs and patches grab onto all the tiny sharp edges of all the components.

After the pots are washed out, you generally might want to apply a MODEST squirt of silicon tuner lube, leaving a lube residue inside the control so it feels a little better and tends to stay non-scratcy longer than a completely dry clean part, or so it seemed to me in my experience. Same caution applies, try to use "just enough" so the lube stays in the pot and doesn't drip grease all over the circuit boards. At best case uncleaned grease on the circuit boards will tend to attract dust and the boards will get nastier quicker even sealed up inside the mixer chassis. Maybe figure out how to make little "over-spray dams" around where you are spraying, like how you try to keep spray paint off areas of an object you don't want spray-painted, holding a piece of cardbord to protect part of the object from the paint spray.

Be careful where silicone lube or possible other lubes get to. It generally won't damage, and probably helps, most metal-contact switches, but I have seen instances where getting a little silicone on the active surface of a conductive plastic switch, such as push buttons on old Prophet 5 or Drumtrax drum machines or many other vintage units with conductive plastic switches, for some reason the silicone and possibly other lubes kills the conductive plastic dead. It doesn't melt the plastic-- The switch just quits working and when I tried to take some apart and clean off the grease from the plastic, my cleaning somehow didn't make the switches start working again, and I had to order brand-new replacement conductive plastic switches to repent of my sin of getting silicone into conductive plastic switches.

You already started spending money on this and I don't want to be discouraging-- I don't do electronic repair any more. But I think a first stage of any mixer repair (assuming the mixer still basically works and doesn't have to be jump-started from the dead)-- Make a very detailed inventory of the state of the mixer and list in painful detail everything that is wrong with it.

First carefully check for excessive hum problems. Test on all inputs and all outputs. Maybe all older devices will tend to get power supply problems as the filter caps dry out and such. But I gather that a lot of older Mackies can develop hum issues as the power supply gets sloppier and sloppier with age. If the power supply shows issues or it seems to hum more than "virtually silent" then that is gonna need sorted. Power supply rebuild or whatever. No matter if all the knobs and switches work if it hums it is useless.

Using a signal generator, or a test tone from a computer or pad, or a looped MP3 file or a synth oscillator-- Check calibration and functionality on every channel and every output. Write down the ones that work and the ones that have problems. Nasty controls, dirty switches and loose/aged ribbon cables could influence your problem inventory, but before you open the thang up IMO you want to know EVERYTHING that is wrong with it, as good as possible.

If you use a mixer in a fixed home-studio environment, changing few connections for years, individual channel problems can creep in and take you a long time to notice. For example if your old Oberheim has been plugged into channels 9 and 10 for the last decade, then if the tone controls or gain of those channels has got messed up over the years you might not notice, because the channels are always set up for that one Oberheim and nothing else. So maybe you have ended up with strange EQ and gain settings to make the synth sound "right" not because of a problem with the synth, but because the channels have got old and quirky, and every channel has different gain and eq than any other channel.

I gave away an old Mackie a few years ago because the hum had "crept up" over several years and finally it seemed easier to give it away to somebody who might decide to pay to fix it, than waste my time fixing the old thing.

Had an old Carvin mini-16 channel mixer I really liked because it was simple and clean and took up very little room. I had it so long dedicated to the same hookups hadn't realized how fubar it had got. Yeah, TSX416 always plugged into inputs 1-4, Kawai K5 always plugged into input 5, whatever. So one day wanted to compare two stereo pianos from two modules, recording them all in one take with the same MIDI-- Synth A to 2 channels and synth B to 2 mixer channels, record two stereo audio tracks into the computer.

So I got to setting the 4 channels flat eq and equal gain, and found out the gain on all four channels was different with the same knob settings and the EQ on all four channels was different with all the EQ knobs set flat. So I got to checking and discovered that ALL 16 channels were FUBAR like that. No channel exactly matching any other channel. But it was still "fairly clean" but probably more distorted than when new. So I just tore it out and put it on a shelf. Maybe sometime fix it but there is a crapload of work it would need to make all the channels work interchangeably. I just gave up and bought a new mixer that didn't have a big long list of problems.

Check gain on channel 1. Check EQ on channel 1. Chect level into all busses and sends. Note any switches that don't work. Then go on and do the same thing to channel 2, all the way up to 32. Sure it is labor-intensive but so far as I know there is no other way to know exactly how FUBAR your mixer happens to be, and without knowing that it is hard to estimate what work needs done, or even how you will know when the refurb is complete. It is complete after you marked as fixed all the items of that big long function inventory you made.

But generally if the thang basically works, just sit down with a 6 pack of beer. Full-range rotate every single knob 50 or 100 times to knock some of the dirt off and maybe spread the jurrassic lube a little better in the old pots. Full-range work every single fader 50 or 100 times. Work every pushbutton 50 or 100 times to knock some of the oxide off the switch contacts. Take a quarter inch plug and then plug-unplug into every quarter inch jack 50 or 100 times to knock some of the oxide off the jack contacts. Same dealie with XLR jacks.

You can do that without even removing a single screw and sometimes will work about as good as anything else if the mixer is already basically working.

Sorry didn't mean to be Debbie Downer.

[BertKoor]

^ good advice!

[Mushy Mushy]

Mushy a couple of thangs

A couple of things? Mate this is one of the most comprehensive replies I've even read here. Thanks so much for taking the time.

Among your many good points your suggestion to do a thorough inspection on the unit stood out. I know there are several things wrong with it, namely constant crackling on a few channels and uneven levels on other channels. As stupid as it sounds in hindsight I wouldn't be able to state exactly what number these channels are. My plan was to simply open it all up, clean everything, replace what can't be cleaned, put it back together and expect it to work. Your approach is far more logical. Sure I'll still clean every channel thoroughly but at least with an inventory of issues I know which areas require more work.

Another thing I hadn't considered is the inserting of jacks, moving slides, pressing buttons 50 - 100 times to loosen the old gunk. Again seems silly to not think of this once you know, but This is something I can do preemptively while waiting for my shopping cart.

Nothing you said in that post was discouraging at all. I typically find enjoyment in keeping old things working rather than throwing them out and buying new. This applies to my cars also where trust me, the amount of "why do you drive that old shitbox" comments have given me a thick enough skin to handle any comments relating to a mixer

Thanks again man. I'm sure I'll be back with a question or two as the work progresses and I work through your action list