ltemma74:
This machine is one of the best cassette 4-tracks ever made. It was the only multitrack machine I had for my first 5 years of writing and recording my own music -- and I wasn't doing acoustic demos, I was going for the full-on, finished "record-quality" approach.
With its additional channels and aux send/returns, there's not a lot you can't do on that thing within 4 tracks of tape. (And I bounced on that thing until the cows came home, doing 8 part + dbl'd lead vox acapella arrangements with up to 28 voices!) The sweepable hi EQ goes upwards of 16KHz or something (tho I think it says 10KHz), and the lows go down deep, below 60Hz. You can get loads of wonderful analog air out of those EQ's. And most importantly, NO awful, overly severe, mix-chewing DBXII NR. The Dolby C on my particular machine always tracked a little less than 100% on playback (decoding), so that sweet forwardness you get from boosting the input gain from the tape on an external Dolby NR unit always showed up to give me that extra creamy presence through the mids and upper mids -- a truly wonderful thing, a real mix polisher. Mastering my recordings through an old ART EQ, mainly boosting the 12KHz by 2dB and 16KHz by 6dB, was almost magic. When it's running up to spec, you're gonna love it.
Now, about getting it to spec. You can see that the mixer faceplate is a big panel that's basically square. Remove the faders' knobs and the 8 screws around its periphery and it will lift right off. From there, if I remember correctly, you can clearly see and access any parts that may be causing problems. If you can find anyone who works on mixers of any kind, this one is simpler than most, and I believe most of the parts should be easy to replace (though that may be my own wishful thinking to some degree. I know I did fix a couple of mixer issues myself along the way).
The parts that are proprietary to the machine are the cassette mechanism and the transport buttons -- and those will break if you press them too hard (i.e., out of frustration when they no longer go into record mode because they're dirty, grr! But I digress). On my machine, the rewind belt got looser and looser until it wouldn't rewind anymore; I had to remove the cassette cover and keep a ball-point pen handy to rewind the tape manually for short runs (and flip it over and f-fwd for longer runs). It's a shame the cassette mechanism as a whole didn't seem to be up to par with the rest of the machine's build quality... or maybe I was just that hard on it. Either way, the cassette mech's speed (more or less the most important thing about a cassette mech) was ROCK solid at either speed (unlike my Tascam 488 whose awful jitter made everything sound like it was playing on a speaker behind a big fan, that piece of crap). Belts and buttons may be hard to replace, but if your machine has relatively low hours, this may not be an issue for you.
Those early mixes from my RMX64 days were simpler and the arrangements less elaborate than what I do now, but as a whole, I'm still proud of the way they sound, and I can't say that for my mixes from any of the machines that followed this one (in order): Tascam 488, Alesis ADAT, Roland VS-880.
All that said, I think the Yamaha MD-8 shows up on eBay now and then for around $120-$150, and it sounds pretty great, too... for cheap & easy digital, anyway.
Speaking of prices, there's an AT-RMX64 on eBay right now for *gulp* $650!! Ridiculous. Obviously I won't be bidding on it. But I do still have all my 3.75IPS 4-track 'master' tapes from this machine, and I'd really love to be able to archive them into ProTools... Yamaha had a few Dolby-C 3.75IPS machines in the mid-late 80's, but they're as rare as hens' teeth. Mind if I ask what you ended up paying for your RMX64?
Best to all,
Robert