I recently finished this fairly uneventful 424 MKIII refurb. I had acquired it about a year ago, and it had been sitting in a box. It turned out that the basic functions worked fine. It just needed some cleanup, calibration and had some cracked solder joints.
During testing, I discovered that the Line Out and Monitor Out RCA jacks seemed a little wobbly when plugging cables into them. Sure enough, output from those sets of jacks was intermittent. Getting to those solder connections requires removing the bottom PCB, which also requires removing the transport. I resoldered the jacks and they’re solid once again.
One of my favorite parts of working with these machines is the cosmetic cleaning. Some of the machines I get are downright filthy, and some aren’t so bad, but we’re talking about machines that are 25-30 years old or so at this point, and many of them have been used hard. I find it really satisfying to clean the front shell, along with all the knobs, fader caps, and switch caps. Then once the machine is reassembled, there’s no dust or crud peeking out from the recesses of the switches, fader slots, and all the other places grime builds up on these things.
Aside from the cosmetic cleaning, I cleaned all of the switches and faders with Deoxit F5, and all of the jacks with Deoxit D5. I cleaned the tape heads with isopropyl alcohol, and treated the pinch roller with MG Chemicals Rubber Renue.
To finish up this machine, I calibrated its tape speed in both hi and low speed, pitch control in hi and low speed, meter calibration, playback levels, and record levels, as well as measured its wow and flutter. Wow and flutter was measured at 0.0355% in hi speed, with a spec of 0.08%+- and 0.0453% in low speed with a spec of 0.10%+-. Because wow and flutter were so low and the main belt looked good from a visual inspection, I didn’t change it.
This machine is up for sale on Reverb here.