This post of Repair Room concentrates on a faulty Scarlett Focusrite 2i4. This unit hails all the way from Portland, Oregon, where it decided to inherit an intermittent problem with the Monitor control. I don’t normally take in interfaces, but to expand my repertoire I figured I’d take on the challenge. Let’s get to it!
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The Faulty FocusRite 2i4
The original problem was described as an intermittent Monitor control knob. For the Scarlett Focusrite models, the Monitor knob controls the volume level of the two balanced outputs on the backside of the 2i4, so this became my first area of focus.
I connected my guitar direct-in to Channel 1, recorded a riff in Audacity, and connected the balanced output #1 to a small Fender Acoustasonic amplifier I have as my testing amp. In this case, there was no problem playing back the recording and controlling it’s volume using the Monitor pot.
I disconnected the amplifier from balanced output #1 and switched it to balanced output #2. This time the signal was non-existent unless I pushed the Monitor knob inwards.
If I held the Monitor knob pushed in and turned it I was successfully able to control it’s level. However, if I released pressure from the Monitor knob, the signal would cut out. This struck me as an obvious problem with the potentiometer. In we go!
Disassembling the FocusRite 2i4
Disassembling the 2i4 isn’t difficult with the proper tools. You’ll mainly need a phillips head screwdriver and a long flat-head screwdriver. After removing the screws from the back-side of the 2i4 I was able to gently pry out the back-side cover.
Once that’s off, looking inside I found two black, plastic clips holding in the front panel. The circuit board was mechanically attached to the front panel, so all that needed to be done was to gently loosen the black, plastic tabs and push out the circuit board.
To access the potentiometer, I had to also disassemble the front panel from the circuit board. Removal of the knobs, two screws, and the nut/washer for the Monitor pot was all that was needed to remove the panel.
FocusRite 2i4 Electronics
The brains of the Focusrite 2i4 is an XMOS XS1-L8A-64-LQ64-C5 commercial-grade 500 MIPS microprocessor chip. D/A and A/D conversion is done by a Cirrus Logic chip and an AK4384 24-bit Sigma-Delta DAC. The USB interface is managed by an SMSC USB3343 Hi-Speed USB ULPI Transceiver and additional flash storage is housed using a WinBond W25X40CL Serial Flash Memory with 4kB sectors and dual I/O SPI.
FocusRite 2i4 Repair
Shifting attention to the Monitor control, the potentiometer used for this is a dual-ganged pot. I noticed a small gap in between the metal cover and the plastic base, and as I pressed the shaft inwards this gap closed.
It was my suspicion that this was the reason behind the intermittent signal in the output on channel 2. Tightening this metallic cover against the plastic base allowed for connection to be re-established. To do so, I used a pair of needle-nosed pliers to pinch the small metal clasps on both sides of the pot.
The outputs were again balanced!
Meet the Author:
Hi, I’m Dominic. By day, I’m an engineer. By night, I repair and modify guitar effects! Since 2017, I’ve been independently modifying and repairing guitar effects and audio equipment under Mimmotronics Effects in Western New York. After coming out with a series of guitar effects development boards, I decided the next step is to support that community through content on what I’ve learned through the years. Writing about electronics gives me great joy, particularly because I love seeing what others do with the knowledge they gain about guitar effects and audio circuits. Feel free to reach out using the contact form!
Spotlight
This fix was done for Buffalo-born and now Portland, OR based band, Seafox. Check out their 2017 album Eulogy of the Angels, as well as their 2018 single “Wasting Time.”
The Tools I Use
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