Tag: 424mkiii

A little over a year ago, a friend from the PedalPCB forum sent me a message saying he had been interested in getting a 424 Mkiii but had never seriously pursued it. He went on to ask if I would be willing to acquire one in decent condition on his behalf, and then go through it and service everything. I agreed, and we began looking at listings. He was particularly interested in this Japanese market mkiii in black. The ebay listing’s condition was “junk,” but it appeared to be in decent cosmetic condition.

When it arrived, it was pretty dirty as these things tend to be. It’s always a little different seeing one of these in person as opposed to photos in an online listing. The knobs and fader caps were typically yellowed as well. Despite the funk level, the machine seemed to be working ok. It also came with a cassette loaded in it, which is always fun. This cassette was also a Japanese market Maxell My2 type ii cassette with a pink shell. I hadn’t seen these before but I like it. It had a song recorded on it, which I ripped and saved before bulk erasing the tape.

Upon disassembly, I discovered that it seems that liquid had been spilled on and in the unit at some point. I gave everything a thorough cleaning- not just the faders, pots, jacks, and switches, but I also scrubbed all of PCBs to remove any residue. I ran into some gremlins at this step of the process and spent a lot of time reassembling and disassembling various things. I ended up testing all of the JST connectors to make sure there were no broken connections. I took long breaks from working on this at several points too.

Here are some more examples of the level of funk this thing had and the results of the cleaning process. I always put knobs, buttons, fader caps etc into an ultrasonic cleaner. I had attempted a simple method of trying to brighten the knobs etc with a bit of success. I have since moved on to another method that works better but I might make a full post about that later.

Aside from cleaning and calibration, this machine also needed a few minor repairs. The first repair was to remove the bottom PCB and resolder the DIN jack for the power supply. The second was to replace the tactile switch for the play button on the transport. I had noticed that it sometimes required two clicks to activate so that got swapped out as well.

I changed the belts on this machine too. The original capstan belt was in decent shape, and the machine had very low wow and flutter, but for peace of mind and longevity, I changed out the belt. Strangely enough, the new belt caused higher wow and flutter than the old belt, but still within the acceptable range noted in the service manual. The machine was also calibrated for tape speed in both high and low speed, the pitch control speeds were checked. Playback level and record level were adjusted back to the service manual specs, and the meters were calibrated.

This machine came out really nice in the end. It’s clean and working as it would have when it was new.

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.