We have completed servicing, calibrating, and testing this TASCAM 414 MKII. This unit is very clean, and after the necessary repairs and switches upgrade, it is working like new.

Cosmetically, it's in great condition, especially after undergoing our deep cleaning process. There are a few little scratches here and there, but overall it's very nice. There's some slight fading on the coloration of the case and knobs.

We tested recording a full tape of music on it, and tested all of the inputs/outputs. It has been calibrated. 

All 4 input switches have been replaced. This is something only we (Functional) do as far as I know. We think of these like Juno 106 voice chips. They eventually go bad so they should just be replaced as part of the standard maintenance.

Grab it before someone else does!

Repairs:

These were need to bring the item back to functioning condition, before performing maintenance.

• All input and output jacks have had their solder reflowed to prevent the possibility of intermittent connections

• The power LED was not lighting up. It has a cold solder joint and this was repaired.

• All four input-select switches were replaced with new parts!

• The item has been deep cleaned in the sink and ultrasonic cleaner.

• The grounding connections have had their solder touched up and the connectors have been cleaned with contact cleaner to minimize electrostatic interference, which is common on these units.

Maintenance: 

With many vintage 4-track recorders approaching 40 years of age, they need to be maintained to continue to work properly. First and foremost the rubber belts need to be replaced, but there are many other things that can keep the 4-track running well.

• Clean and demagnetize tape heads

• Replace belts with low wow/flutter belts

• Oil capstan bearing with high quality German oil. It greatly improves wow/flutter

• Clean all input and output jacks with Deoxit on a cue tip. No messy spraying.

• Clean all potentiometers and faders with contact cleaner

• All 1/4", RCA jacks, and the power jack have had their solder reflowed to ensure strong reliable solder points.

• The transport buttons were disassembled and cleaned with the ultra sonic cleaner, because why not!

• A common issue with TASCAM 414’s and 424’s is the INPUT and record-select slide switches become dirty and do not work properly. When this happens, the signal can cut in out and out in playback or recording. We make it a point to disassemble the mixer and thoroughly clean these switches multiple times with contact cleaner, and then Deoxit concentrate before reassembly.

Calibration:

Aside from calibrating the tape speed which is required after changing belts, often the rest of the calibrations are fine from the factory, but we check them and make tweaks when necessary.

• Calibrate tape speed(s)

• Check/calibrate the Azimuth

• Check/calibrate the playback level for even playback

• Check/calibrate the record level for even recording

Cleaning:

We also take pride in restoring the cosmetic condition of the units we work on. Note that in some cases there are stubborn marks that we leave. Rather than scrub them away with a harsh cleaner which can damage the original finish or patina and leave the unit looking spotty.

• All knob and fader caps were cleaned with an ultrasonic cleaner.

• In some cases when the faceplate is removed we clean it in the sink with soap and water and dry it completely before reassembly.

Quality Assurance:


We also do a thorough QA of all our units. This process includes hooking the unit up to a vintage Hammond drum machine, Nord organ, and various other gear. We then record music on all 4 channels, and test all the functionality that would be used when recording music. It only gets listed once it has been tested this way. If any issues are found, we fix the issues before listing. This ensures that the unit is functioning as it should without a doubt! 

Other notes:

• It comes with a new power supply and bulk-erased vintage tape. Vintage tapes are the best in our experience.

• Free USPS ground shipping. Will usually ship same day.

We also have other machines for sale. Check out our Reverb Store: https://reverb.com/shop/functional-tech-sf

Need your 4-track serviced? Reach out to us via direct message or our website for availability and rates. We are located in San Francisco, CA. See our website functional.fyi for more info.

Also check out our product Lucky Cat LFO if you're into modular synthesizers!

Internal Id: Oct 11, 2026


Listing Date: G393