The overall structure and layout is virtually identical to its "older cousin", the Saffire Pro 40 (apart from the Firewire vs. USB connectivity, and the newer unit having a Wordclock output).
This time, this is getting done right: not turning it on, but taking it "apaaaah't". That being said, i'm most definitely not the first one taking this step, what with the 10 out of 14 screws missing, from the ones securing the top cover to the chassis.
I see some vague mod attempt - four added electrolytics, in parallel with the pre-existing 1210 SMD ceramic caps, in the vicinity of the group of opamps dealing with, most likely, the analog outputs. I highly doubt this was a factory bodge - i had cracked open one of these 18i20's a couple years back, and there was no trace of any "afterthoughts". Leads were left quite long, but at least they're secured to the circuit board with a dollop of hot-melt glue.
But better not get ahead of ourselves, eh? Starting off with the power supply - nothing to write home about, really. Just your bog-standard flyback converter, with multiple outputs. The main silicon is a CS8N50F N-channel MOSFET, and an MBR10100CT dual 5A 100V Schottky rectifier (for the 5V and/or 3.3V rail). The controller's most likely some 8-pin job, along the lines of a UC3842.
CapXon electrolytics though - never a good sign. Almost exclusively, save for the odd Jamicon here and there.
The power section of the circuitry continues on the mainboard - an LM317 / LM337 pair regulating the +/-6.9V for the opamps, and another LM317 handling the phantom-power rail.
A TI LP38692 low-dropout regulator supplies the 3.3V rail.
A tiny little OnSemi NCP1529 provides the 1V rail for the processor cores.
Speaking of which - as opposed to the Scarlett 18i8 we had a look at a little while ago, the 18i20 rocks not one, but TWO Xmos processors. The physically larger, TQFP-packaged one is an XS1–L8A–64–LQ64–C5 (8 cores, 500MIPS), while the smaller-but-heftier one is an
XS1–L16A–128–QF124–C10 (16 cores, 1000MIPS). The firmware is stored in the adjacent Adesto AT25DF041A 4Mbit Flash chip.
An SMSC (now Microchip) USB3343 is in charge of the USB interface, just as in the smaller Scarlett 18i8.
Keeping with the digital side of things, a Cirrus Logic CS2300 PLL is used. And off towards the edge of the board, a National Semiconductor (now TI) DS89C21 differential line driver handles the S/PDIF output.
The audio conversion is handled by a quartet of Cirrus Logic CS4272, plus an additional CS4392 (since there are ten analog outputs available).
The analog side of things is made up mostly of JRC NJM4565 opamps, plus eight NJM2122's on preamp duties, plus a pair of TI TL072C's for the high-impedance instrument inputs. The smattering of NXP (now Nexperia) HEF4052B and HEF4053B analog muxes does all the signal switching & rerouting between the mic inputs, line inputs and instrument inputs.
More NJM4565's in the analog output area, along with the pair of Panasonic / Matsushita TQ2 relays, for muting the main stereo output upon power-up and power-down.
I told you the "family resemblance" with the Saffire Pro 40 wasn't a coincidence - the front panel is literally identical. Well, the part that matters, anyway, ie. the circuit board.
And last but not least, a pair of NJM4556A's drive the two headphone outputs.
Right-o, with all that out of the way, time to power this thing up, "at long last". All the power rails check out fine. And as i had suspected, the added-on caps are indeed on the "Vcom" half-supply bias outputs, coming from the DACs.
Driver / MixControl detected it just fine upon plugging in, firmware update was succesful. All that's left is to hook it up into (or rather, through) my system here, and wait / hunt for issues.
About an hour of music listening later, no issues. Granted, i updated the firmware to the latest version (from the latest beta of MixControl, 1.10b3 as of right now), so for all i know, that might've already mitigated the problems, but i suppose only time will tell. I'll add any updates here, if any come up.
hi do you have the distributive of mix control 10b3 for windows? I see a focusrite pulled it from their beta site
ReplyDeleteI'm pretty sure they turned that into the latest official (non-beta) release, on their "normal" download page.
Deletehttps://customer.focusrite.com/sites/customer/files/downloads/Scarlett%20Mix%20Control%201.10%20%2B%20Windows%20USB%20Driver%204.63.23%20%20-%20Release%20Notes.pdf
https://customer.focusrite.com/sites/customer/files/downloads/ScarlettMixControl_1.10_USB_4.63.23.563_Installer_522.exe
thank you. I found links to 1.10b3 pointing at their beta site but it was removed. and the location of 1.10 release version is a bit obscured. as it is not mentioned at support page you find just searching for 18i6
DeleteAnd you need / want 1.10b3 because....?
DeleteAs i said, to the best of my knowledge, 1.10b3 became 1.10 "final", that's been available for public download.
1.10 "final" shows up as the only Windows version of MixControl whether i look up 18i20 or 18i6.
https://customer.focusrite.com/support/downloads?brand=Focusrite&product_by_range=428&download_type=all
Hi,
ReplyDeleteThats very interesting!!!
I have the same sound card and my both headphones output are saturating / crackling. My outputs work well.
I opened it to see if I can do something but I'm lost.
Do you have any idea of what I could check? I do not want to bin my card!
Thanks in advance
So all the line outputs on the back are fine? You're 100% sure the problem is strictly just on the headphone outputs?
DeleteDo your headphones work fine with other sources (AV receiver, phone etc)?
Yes ! Sure ! I use all my others outputs. My workaround is to use the monitor outputs with a behringer mixer, and to plug my headphones on it. But I'd like to use directly the headphones output ;)
DeletePreviously I let my sound card unplugged many weeks and it didn't did it anymore during few days.
So then, the issue sounds like it's pretty much isolated to the hardware headphone outputs themselves. I assume then, that line outputs 7-10 are not showing the same symptoms?
DeleteDo they distort at any volume level? Or just above a certain setting on the headphone volume pots?
It distorts at any volume level.
DeleteI'm quite sure that the issue come from the hardware headphone outputs as you say. At the beginning just one of the both output was ko but now both are defective. Some time the sound can switch to one side to the other too.
All connectors from the back work and I use them very often.
If it happens at any volume level, then the problem is from before the headphone volume pots.
DeleteMight be worth trying replacing those four small electrolytic caps that are right there - judging by the pair of traces that go between the two connectors that go to the volume pots, they're likely right before the volume pots (to make sure there's no DC across them).
That same pair of traces goes through the "i" in the Focusrite logo silkscreened on the board, and ends in two vias. I'm pretty sure those connect to the outputs of the low-pass filter opamps that are on the outputs of the DACs. If the line-outs 7-10 are fine, but the headphone outs aren't, those input caps would be my prime suspects.
Thank you ! It helps me. I will try to find help to replace them.
DeleteIts great seeing people looking into fixing their hardware rather than just scrapping it.
ReplyDeleteI've got a later generation of the same interface and Channel 5, one of the microphone inputs, no longer works. I'm assuming its blown from a phantom power issue at some point. Im guessing there are no fuses on the inputs. Any idea what components might need fixing?
"Later generation" meaning 2nd gen, surely; the 3rd just came out this year.
DeleteI seriously doubt phantom-power would've caused anything like that, what with all the DC-blocking capacitors, as well as the diode-clamps on the preamp inputs. That, and the phantom-power being fed through 6.8Kohm resistors, as per standard.
I assume neither the XLR nor the TRS inputs work on the faulty channel?
What would be great to have (or even just borrow), would be an oscilloscope, to easily probe / trace / follow the signal path and see where the input test-signal "ends".
In a pinch, i might even go as far as to use the unit to test itself, as it were. Cobbling together a test-cable (1/4" mono jack and a shielded cable; center conductor as the probe tip; cable shield not connected to anything), and using one of the hi-Z inputs on the front, and using something like RoomEQ Wizard (or your favourite DAW with the appropriate plugins), you could produce a test-signal on an output, wire that into the faulty input, and monitor the signal in software.
The handily-labeled test-points, at least on this 1st gen, are after the NJM2122 preamp (balanced-in / balanced out) and one half of an associated NJM4565 (balanced-to-single-ended converter). Seeing if you get a signal there will quickly show if the problem is "upstream" or "downstream" of that point, and then work from there.
I had a problem with the gain pots not increasing the gain on channels 2 and 8 on my 18i20 1st gen, just took the top off it and gave the connectors to the pots a gentle wiggle/push and now they are fine, just thought the info might be useful for anyone having the same issue with this interface, as it seems to be fairly common.
ReplyDeleteTHANK YOU! I stumbled upon this; had pots 3 and 8 not working, I opened up, disconnected cables from the pot end and reconnected. Worked great! We'll see how long it lasts....
DeleteHi, where did you find the decoding of the name of the Xmos chip model? I have a problem in the Xmos chip in the 2i2 audio interface and I cannot figure out where to buy such a chip. thanks
ReplyDeleteFor what it's worth, you'll find more details about the (1st gen) 2i2 right on this blog .
DeleteRegarding "decoding" the part number, it was mostly down to persistence. The markings are mentioned in the datasheets of the respective chips, but Google doesn't always show the best (or correct) result first, so it sometimes needs a bit of digging.
I have a 1st Gen that is faulty. Sometimes it'll turn on and immediately turns off. I opened it up and looked for leaking caps and domed caps but didn't see anything. When I had it open, I also flipped the switch a few times and noticed the led2 and led3 flash instead of stay on, then led4 flashes as well which normally flashes when you power off. Any tips to track down the issue, or have an idea?
ReplyDeleteThat's not really a whole lot to go on. Do you have (and know how to use) at least a voltmeter / multimeter?
DeleteI didn't figure it would be much info. But yes I both own and know how to use one. Where should I be testing?
DeleteStarting with the various supply rails would be good - luckily they're nicely marked on the board.
DeleteLD3 seems to be between the +/-6.9V rails that power the opamps, so if that's not solidly on, the suspicion quickly moves onto the power supply. Prime suspect would be the small electrolytic capacitor(s?) on the primary side, that helps power the controller. Should be something in the range of 22-100uF.
Replacing it with a good-brand low-ESR one would be my first step. If that doesn't help, then the suspicions move to the secondary side of the power supply.
Nice teardown. Do you have any insights about the front panel display? On my new-old 18i20 gen1 the level indicator is dimly (and evenly) lit all the time, but doesn't show any levels, even though the audio path seems fine and levels are shown in MixControl. Are the indicators normally blacked out on no-signal?
ReplyDeleteI would imagine they would indeed be off, with no levels. Pretty sure there's a serial stream of on/off signals being sent to the front panel, and there are a few serial-to-parallel decoder chips that split that up to the appropriate LEDs.
DeleteNot quite sure where to start troubleshooting that, though. Do the other LEDs light up fine? Thinking mainly of the Dim and Mute ones, which are "software-controlled"; the pad / phantom / HiZ ones may well be hardware-switched (all the buttons there are DPDT latching switches, while the Dim and Mute are momentary ones).
Hie Khron. I have a Scarlett 18i20 1st gen that simply won't connect to any computer. I have changed cables, computers and power cycled everything. Would you be able to give some insight into what could be wrong? Maybe a hardware reset could be located inside the device itself?
ReplyDeleteThank you.
There's no "hardware reset" that i've seen. But does the unit still boot up, and react primarily to the Dim and Mute switches? If it does, the processor and firmware might / should still be fine. If that's the case, the prime suspect would be the little USB interface chip (SMSC / Microchip USB3343).
DeleteHi, and thanks for excellent info👍 Do you know where i can get the headphone module, as both mine og mine is pushed to hard in by previous owner.
ReplyDeleteBy "module", do you mean the 1/4" stereo jack socket itself, or...?
DeleteThank👍 No, I mean the heile 5x5cm PCB with to Jack socket and 4 murata filters😃
ReplyDeleteI can order the filters, but the jack sockets I am not shure witch one to get. They are marked with "J. T."
DeleteAnd sorry for my english, norwegian spell checker😃👍
DeleteIs the board itself still in one piece? Any pads / traces torn? Or maybe you can leave a link to some photos?
Deletehttps://www.dropbox.com/s/wqtzawm3sdfz3ma/20210217_202833.jpg?dl=0
DeleteThose look a lot like a couple jack sockets i removed from a MOTU 828mk2 a while ago, to make room for some mods.
DeleteTechnically, those filters aren't 10000% necessary for the headphone outputs to work, they're just there to filter out any radio-frequency interference.
If you want, i could mail you these jack sockets (they're just gathering dust here, really), but i don't know if i have where to scavenge those sorts of filters right now...
That would be awesome :-)
DeleteWhere can I find contact info? mine is hexoko at gmail com
PS: I`ll pay you for the shipping, of course :-)
Deletehello, I'm a technician and I have a problem with a Scarlett 2i2, do you have an email for contact?
ReplyDeleteIt might have been a bit more useful to post this in the 2i2 teardown article. But what sort of problem are you having?
DeleteI'm having a problem can you help me.. my focusrite is the same type in Gen 1, I have a floating sound that doesn't focus, so the stereo output jack at the bottom doesn't produce sound when plugged in, but when plugged in it doesn't come out full. . even though the jack in Focusrite has been replaced with a new one but it's still the same... how to solve it... is it because of a weak output ic or what?? thank you 🙏🙏
ReplyDeleteI'm sorry, but that description is really not clear. "Floating sound that doesn't focus"? And which "stereo output jack" do you mean?
DeleteHi, im having a problem with two input channels, 5 and 6 where they show a constant noise signal on the front pannel, and on the digital side of things (DAW) it shows clipping on both channels, i tried exchanging the 2122 and the 4565's to see if one of those CI's were falty, would you help me with some tip of what to do next? i love this interface and i want to repair it myself if it is possible. haha
ReplyDeleteWell, replacing parts "blindly" is rarely a good idea, first of all...
DeleteBut in case you had access to an oscilloscope, or at least a multimeter, that could help track down the actual root cause of the issues you're facing.
i have access to both, i have quita a workbstation here, hehe. what do you sugest i do?
DeleteThanks for awnsering by the way.
No problem, glad to be able to at least try to help.
DeleteWell, the more systematic route would be (or would have been) to feed a constant test signal (a sine wave, even using one of the 18i20's own outputs) into the suspect inputs, and try to follow the signal flow, from the connector all the way to the converter inputs. If all is clean and noiseless there, that would rule out the preamp(s).
But since both channels 5 and 6 are affected, that would actually start pointing the finger at the associated converter (one of the CS4272's). Might want to make sure its Vref voltage is constant and clean (see datasheet for details and what pin it comes out of).
Hi you have the electronic diagram of the 18i20
ReplyDeleteNo, i don't. Why do you ask?
DeleteHi, how are you?
ReplyDeleteI'm trying to fix an issue with the dim function turning on and off intermitently, it doesn't matter if it is usb connected or not.
I just dont know where to look
That's a really odd one. Could the switch itself be faulty? Apart from that, perhaps a firmware issue?
DeleteJust to add to this, mine is doing the same thing. Firmware latest version, switch itself works fine. It's like audio coming in passes some threshold and throws the dim switch intermittently, incredibly annoying.
DeleteIf it's of any use to you guys (as in, if you have the facility, or know someone who can reflash the contents of the firmware chip), i have dumps of the 634 and 1056 versions.
DeleteI just started having an issue with mine where it's making a continuous clicking/chattering noise (basically as if the normal startup clicks continue, but it never stops and it's very fast). The sound appears to be coming from the ld2/ld3 section with the two inductors(l15/l14). Oddly, this one has a CS8N60F in the power section (and it gets extremely hot within seconds, while the lower power mosfet is ice cold, but then there's a reason for heat sinks). The two leds stay on, but the clicking/rattling/whatever never stops. It just started the other day, after being powered on for a good while. The sound is also able to be manipulated by turning the gain up on any/all channels. Any ideas?
ReplyDeleteI wouldn't be surprised if some of the electrolytic capacitors in the power supply were on the way out (and in the process, destabilizing the feedback and causing the extraneous noise and uncertain startup).
DeleteWell, it turns out that, upon turning it on again for a few moments to see if I could identify exactly where the ticking sound was coming from, the power board went poof. Lost 5 of the smd caps on the bottom. Replaced those, along with the PWM, and that cs8n60f, but I still get no power. I'm guessing the massive 82uF 450V cap went with everything, but I can't see anything else obvious that let out the magic smoke.
DeleteGot any photos of the issue(s)?
DeleteI've got a 18i20 gen 1 and it has a horrible crosstalk between channel input pairs (1-2, 3-4 etc). Looking online it looks like it was a defective batch from production. I am in touch with Focusrite but I doubt they will help me now. I don't have those capacitors added, why do I have a feeling that that is the fix for the excessive crosstalk? Mine also has 50hz background noise - and it looks like it's one of the caps in the PSU - and the 1V for the CPU sometimes does not come up - Enable pin and 3.3V are present so I have ordered a replacement for the regulator. Thanks for this page - it will be mentioned and linked on my video repair!
ReplyDeleteJust skimmed through the video - thanks here too for the shoutout, and that's some interesting extra information to know!
DeleteHello again - further my previous comment, I can confirm the bodge work you found with the capacitors is indeed factory and it's there to mitigate some excessive crosstalk apparently common with gen1 interfaces. This was confirmed by Focusrite themselves. I made a video of this issue with some extra repairs, this blog and this page is shown and linked! :) Thanks for your help!
ReplyDeletehttps://www.youtube.com/watch?v=KIKap35spNY
Thanks yet again! And sorry i haven't been active here a lot, life's busy. And i have to have comment moderation on, because i guess this is "big" enough for spam bots / scripts to try to infest, so... Yeah :P
DeleteBut much appreciated, either way!
Of course no worries - thank you!!
Delete