Repair Usb Audio interface Focustrite 2i4 - Page 1
Forum section: electronics / repair

author: firstcolle
author_rank: Regular Contributor
timestamp: October 02, 2017, 09:02:04 am
content: Hi,I have a focusrite 2i4 that has some problem..it's power up and windows recognize it, the power led is on but the input signal is not revealed on the led meter and obviously nothing came to PC...I can't find a schematic or a service manual..inside I notice these things:- no visible damages- +3.3 v rail OK- DC/DC converter very hot- 0V on the +V -V op-amp pins (they seem to be shorted)what can I check? I think I can remove the input op amp and see if the +V -V rails works. something else before this?thanks

author: sarel.wagner
author_rank: Regular Contributor
timestamp: October 02, 2017, 02:32:36 pm
content: My 2i4 also gone, got accidentiall blown up by 12v supply... ooops

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 02, 2017, 04:46:46 pm
content: If the power supply is "very hot" and there is 0V on the power rails, a common failure mode is that something is shorting out the power source output(s). One prime suspect is electrolytic capacitors across the power rails. Those components are rather more prone to failure than more robust components like resistors or the smaller capacitors. Of course, another possibility could be that one of the ICs (likely op-amps) has failed and is shorting between the positive and negative rails.However, the simultaneous failure of BOTH the positive and negative rails rather casts suspicion back on the DC-DC power gadget (or somewhere in that neighborhood).There may be a bootleg copy of the 2i4 schematic out there on the interweb somewhere, but a quick search didn't reveal anything promising.

author: firstcolle
author_rank: Regular Contributor
timestamp: October 04, 2017, 07:15:24 am
content: Hi,you're right, no schematic found on the internet.to be precise I have +0.7V on the positive rail and -0.44 on the negative rail. but when I shout down the board the positive and the negative rails seems to be shorted to ground.I put a shot here, the chip with the red dot on top is an ISL97519A and it's hot when powered. This chip seems to be only a step up reg. so, where the negative rail come from?on top there's another identical chip that is colder but I think it's used for the +48V phantom power that works without problems.I removed the electrolytic caps with the red dot on top but the shorts still remains.

author: firstcolle
author_rank: Regular Contributor
timestamp: October 05, 2017, 05:56:40 am
content: faulty ic found!!!it was a 74HC4066 on input n.1. removed it and the short to ground was gone. +5v -5v rails came back!!!

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 05, 2017, 06:22:32 am
content: That is quite excellent. Congratulations on a great outcome. 4066 are rather a jelly-bean part available everywhere for pennies.

author: Rasz
author_rank: Super Contributor
timestamp: October 05, 2017, 12:02:44 pm
content: Quote from: firstcolle on October 05, 2017, 05:56:40 amout of curiosity, was it a lucky guess or was 74HC4066 boiling hot?

author: firstcolle
author_rank: Regular Contributor
timestamp: October 06, 2017, 10:01:11 am
content: it was only luck... I started to remove the ICs near the input stage and the 74HC4066 it's the nearest to the input jack..

author: Airman
author_rank: Newbie
timestamp: April 28, 2018, 06:58:29 am
content: Hallo everyone.One day I damaged ic sot353 described SDERWZ. This ic is behind USB port. Symbol on PCB is U38. Somebody know what it is ?Thanks for answer and sorry for my english.

author: thxsound1138
author_rank: Newbie
timestamp: November 09, 2018, 06:11:22 am
content: Hi,U38 is NCP303LSN09, and L5 is DLW21HN121.Cheers.

author: EHT
author_rank: Frequent Contributor
timestamp: November 09, 2018, 08:21:38 pm
content: Bit off the original topic but I use one of these and it has a very intermittent fault; I'm interested to know if anyone sees the same.Very occasionally (like once a week or even less) the sound output suddenly becomes extremely distorted when it is in use. If I simply toggle the output audio device setting in Windows to another device and back again then it reverts to normal.I wonder if this may be a bug in the driver software. I have driver version 4.36.5.612 which is the latest as of Nov 2018. I have it connected via a USB hub (EasyAcc H40) which may not help. I would have preferred if it had a separate power input instead of being bus powered. For one thing, i keep forgetting to turn off the amp when i reboot the PC. Speakers not happy...Anyone else observe this or have a view? Perhaps i should report it to the mfr; unusually I did actually buy this new and haven't even taken it apart!Thanks!

author: thxsound1138
author_rank: Newbie
timestamp: November 10, 2018, 03:21:18 am
content: Quote from: EHT on November 09, 2018, 08:21:38 pmHi,Sounds a lot like a software issue on the computer. Do try it on another computer to confirm your suspicions, but my money is on the computer/driver/buffer settings. Also, there have been cases where I connect to a different USB port and the issue vanishes. Perhaps try going direct without the hub to troubleshoot further.

author: DaJMasta
author_rank: Super Contributor
timestamp: November 10, 2018, 04:59:06 am
content: Definitely sounds driver/operating system sound system related, may be worth disabling some other devices or reinstalling drivers/updating firmware as applicable (maybe even reverting to an earlier version). If you have test equipment, specifically an oscilloscope, you could try probing around some signal lines internally to see if it's showing up as real noise on the input.... but from the description, it would be tough to spot (maybe single shot trigger on clipping levels?), and I still think it would likely not appear when you hear the glitch.

author: gabrielcsr
author_rank: Newbie
timestamp: December 18, 2018, 12:58:02 pm
content: Can someone help me?I let my 2i4 fall on floor. Seems to be this 2 places (u38 and r51) the missing parts. what is the name os the parts?i just find this post for coincidence. I have no knowledge on eletronics. I just want the name of the parts to send the device to repair. Because the guy on the assistence say i can't find the piece to replace. Sorry for my bad bad english. Thanks.

author: ElecSeb
author_rank: Regular Contributor
timestamp: December 18, 2018, 01:44:32 pm
content: This cannot be the result of a drop, seems more like a crappy repair job...Furthermore, U38 is defined in an earlier post.R51 seems to be an 473 (47kΩ ± 5% Read morehttp://www.resistorguide.com/resistor-smd-code/)

author: gabrielcsr
author_rank: Newbie
timestamp: December 18, 2018, 01:48:04 pm
content: Many Thanks! Is this the right part to buy?https://www.ebay.com/itm/10-PCS-NCP303LSN09T1G-TSOP-5-IC-VOLT-DETECT-OD-0-9V/322633795853?hash=item4b1e79090d:g:u8UAAOSwvv9ZhBX4:rk:1:pf:0

author: psfm
author_rank: Contributor
timestamp: February 04, 2019, 08:10:35 pm
content: Hello,It was really good to find the thread.I'm having problems with my 2i4 as well and I'm in a dead end.Don't know if someone can help me, but these are the symptoms:• Scarlett turns on• no audio output• computer recognizes the device (I can select the device under mac os x system preferences)• I am able check the connection on system information/ usb devices (i.e. maker Focusrite; version 1.25; current used 500mA; etc)• I can change sample rate through computer's audio device manager• green circle lights around the inputs stay on after rebooting• on tp6 I can measure 47.72v (whether the phantom is on or off)• on tp1 I can measure 3.22v• AKM 4384ET (VDD 5v)• Cirrus Logic CS4272-CZZ (VA 4.94v/ VD 3.2v/ VL 3.2v)• all four HC4066 (VCC 4.96v)• XMOS XS1-L01A-TQ128-C5 (all VDD 1.08v/ all VVDIO 3.23v/ PPLAVDD 0.99v/ PCU-VDDIO 3.23v)What I've done so far:• usb cable swapping• usb port swappingKind regards,M

author: psfm
author_rank: Contributor
timestamp: February 05, 2019, 04:47:35 pm
content: Hello,I just found that I can record an input signal, with both inputs, but the wave is rather strange: it is negative. Can this mean that there is a short circuit?Thank you,M

author: KhronX
author_rank: Frequent Contributor
timestamp: February 24, 2019, 12:33:40 pm
content: Your inbox seems to be full-------My idea was to use that second interface, with a cable ending with a 1/4" connector plugged into a Hi-Z (or "instrument") input, and using an oscilloscope plugin in a DAWYou would be using the inner conductor (twisted up and soldered, to keep it stiff, or solder a solid-core wire as an extension / tip) as an improvised oscilloscope probe.There's pretty much no chance of damaging anything in the second interface - inputs are usually AC-coupled (ie. through a capacitor, to block DC), and you have the adjustable gain anyway.We don't care that much about the exact / absolute amplitude of our test-signal, only that it gets through to where it should.Is any of this making any sense?

author: KhronX
author_rank: Frequent Contributor
timestamp: February 24, 2019, 12:39:11 pm
content: A while ago, i ran into similar issues with my Scarlett 18i6, but i ended up... well, either finding the issue, or at least somewhat mitigating it.I've been using this little program called ThrottleStop for years, to control the speed (and thus the heat output / power consumption) of the cpu in my laptop (which is my daily-use docked machine).The issue seems to crop up when the turbo is active (ie. ramping clocks up under load, winding back down at idle).That (audio corruption) has never happened since i've started keeping the cpu locked at max non-turbo clocks.Quote from: EHT on November 09, 2018, 08:21:38 pm

author: braianokonnor
author_rank: Newbie
timestamp: March 05, 2019, 01:06:52 am
content: Hi there, i got an 2i4 1st Gen.. the issue... the pc can detect it correctly but no input and output.. i noticed that the L12 C86 Gets super hot quickly right someone knows about it?? theres a red dot on the pic on the faulty piece..

author: wraper
author_rank: Unknown
timestamp: March 05, 2019, 01:14:56 am
content: Quote from: Richard Crowley on October 02, 2017, 04:46:46 pmLow voltage electrolytic cap going short is quite extraordinary occurrence. Going short (in low voltage circuits) usually means faulty semiconductor devices or sometimes MLCC.

author: wraper
author_rank: Unknown
timestamp: March 05, 2019, 01:19:24 am
content: Quote from: braianokonnor on March 05, 2019, 01:06:52 amIt likely means that power rail coming from this DC/DC converter is overloaded for some reason. Part that heats up likely is fine. You should measure the voltage on this power rail first.

author: braianokonnor
author_rank: Newbie
timestamp: March 05, 2019, 04:34:59 am
content: can someone help me whit some reference to check that voltages.. please.. no schematic on internet

author: Countrypicker
author_rank: Newbie
timestamp: January 20, 2020, 10:04:33 am
content: Hi Guys,I recently bought a faulty Focusrite Scarlett 2i4 from eBay. The description was " For spares or repair - does not power up" The pictures showed a broken USB connector so I figured this would be an easy fix. However when I opened the unit I discovered the previous owner had tried to repair it himself and shorted the data pins to the 5 Volt rail with solder. The result was several components blown off the board. I have managed to identify most but struggling with U39. It is a 6 pin chip[ labelled something like Z047 but it is very faint so I'm not sure what it is. The chip may be ok but there is a missing resistor (R51) so I suspect the chip could have taken a surge and I would like to replace it. Does anyone know what that chip is?

author: magic
author_rank: Super Contributor
timestamp: January 20, 2020, 10:10:59 am
content: USB 1.x/2.0 devices should tolerate shorts between any two pins indefinitely.That being said, maybe that's too much to expect from audio gearPost a pic of the blown parts and their neighborhood.

author: Countrypicker
author_rank: Newbie
timestamp: January 20, 2020, 12:35:12 pm
content: Hey Magic, thanks for the fast reply. I'm at work right now but I will take pics when I get home (Based in Scotland). I just figured out what those codes are (SMD Codes). I'll use a big magnifier and see if I can decipher the code. I used to be an electronics tech way back in my Air Force days but they didn't use surface mount components in those days. (Old Timer). Regarding shorting out pins, I wonder what 5 volts down the input pins of the USB Controller chip would do. It already blew off the little inductors at the input. Also blew off chip U38 and R51. I have ordered a USB3343 chip just in case.

author: Countrypicker
author_rank: Newbie
timestamp: January 21, 2020, 11:53:53 am
content: Pics attached. I found U38 detached inside the casing. It is marked SDERCG. A previous comment says this is NCP303LSN09 but I think that's wrong. I looked up the SDM code and it says LM3670MF-3.3. That's a DC Voltage drop down device 5 Volts to 3.3. Makes sense as the Processor, USB Controller and the Cirrus Logic DAC all use 3.3 volts. U39 is marked Z074. That appears to be a Fairchild NC7WZ07P6X Dual Buffer. The middle 2 pins appear to be unconnected so that ties in with the Chip schematic. C137 should be 1 uF capacitor according to USN 3343 Data Sheet.

author: Zucca
author_rank: Unknown
timestamp: January 21, 2020, 12:30:14 pm
content: Quote from: Countrypicker on January 21, 2020, 11:53:53 amStrange, those do not came off so easy, do not spit on my face but maybe is overheating and desoldering itself?It's a mistery.

author: Countrypicker
author_rank: Newbie
timestamp: January 21, 2020, 12:56:55 pm
content: R51, L5, C137, C139 all missing. C137 should be 1 uF according to the USB3343 Data Sheet. Not sure about C139 - maybe it was never there. This was caused by someone trying to replace the USB connector. He shorted the Data pins to the +5V line with a solder splash.

author: Zucca
author_rank: Unknown
timestamp: January 21, 2020, 01:07:19 pm
content: Another moron before us, very common story unfortunately.

author: magic
author_rank: Super Contributor
timestamp: January 21, 2020, 02:10:36 pm
content: Quote from: Countrypicker on January 20, 2020, 12:35:12 pmNothing interesting in principle, though I haven't had an opportunity to test it in real life yetUniversal Serial Bus Specification Revision 2.0, 7.1.1 USB Driver Characteristics, page 124QuoteI will tell you what happened: the previous owner knocked these components off the board while trying to replace the USB connector. Or maybe desoldered them and couldn't put them back. Or lost them, or broke them during desoldering.Either that or he managed to apply mains voltage to the USB input. But there are no smoke stains.As for the data lines, I bet they go straight through L5 to U4. L5 was a common mode choke to suppress EMI, the device will work without it (replace with two straight wires). Then you may look for a proper replacement, but I am not familiar with that stuff.The only serious problem is the mayhem around U38. You need to identify it. It doesn't look like a switching regulator, because there is no coil in the vicinity.editTrace how things are connected around U38 and U39 and post a schematic.That guy from Poland has 47kΩ at R51. Both he and the Brazilian have nothing at C139.Is your U38 visibly broken or only disconnected from the board?

author: Countrypicker
author_rank: Newbie
timestamp: January 21, 2020, 04:51:17 pm
content: I see from other pictures on the web that C139 is empty so can rule that out. Yes, the data lines do go through L5 to pins 13 and 14 on the USB3343. I have a replacement choke for L5. I am fairly sure I have correctly identified U38. (LM3670MF-3.3) The part I found rattling around inside the device has no connections to solder it back in. Just a black chip with no legs and marked SDERCG.

author: magic
author_rank: Super Contributor
timestamp: January 21, 2020, 09:50:07 pm
content: I wonder if this thread might be about the same one unit which is being broken a little bit more by each new owner and then sold on eBay to the next oneU38 is not LM3670-3.3, don't try it. Firstly, the marking doesn't match (SDER vs SDEB). Secondly, there is no inductor nearby so U38 wasn't an SMPS chip.Too bad that the original part is nonfunctional. NCP303LSN09 is a reasonable match (the datasheet says: marking SDE). You may order a new one and see if it looks the same (same number of letters, font style and size).Try to figure out how the circuit is wired and whether NCP303LSN09 makes sense in this place in terms of pinout and function.

author: Countrypicker
author_rank: Newbie
timestamp: January 22, 2020, 11:05:37 am
content: Thanks Magic. NCP303LSN09T1 ordered.

author: stuartmp
author_rank: Contributor
timestamp: July 11, 2020, 11:27:45 pm
content: Hi Guy'sJust wondering if someone can tell me the value of R40 on a Scarlett 2i4 as I somehow blow it up last night.See attached image for the locationI'm assuming that once I know the value I can just replace it the a regular 1/4 watt resistor of the same size.Thanks

author: magic
author_rank: Super Contributor
timestamp: July 12, 2020, 06:38:19 am
content: A more interesting question: what it is doing there and why did it blow up out of a sudden?

author: stuartmp
author_rank: Contributor
timestamp: July 12, 2020, 08:13:44 am
content: I was just switching over a whole heap of leads over not paying attention. Do you know the value of R40?The device seams to be working fine otherwise. So I don't really know what it does. I traced on end to the phantom power switch and the other end to the IC near by.

author: magic
author_rank: Super Contributor
timestamp: July 12, 2020, 10:18:04 pm
content: I don't own this device so can't help.Se what IC it goes to and find the datasheet. Chances are that this circuit just follows the chip manufacturer's reference design.

author: diegooo1972
author_rank: Newbie
timestamp: August 16, 2020, 01:03:47 pm
content: I had a short between 0v and 5v. I finally isolated with the best analyzing instrument ever. The thumb. The problem riside in a componet marked as IAFEF. My best guess after few serach is that is compatible with IAFEE which seems to be a MP2159GJ-Z (wrong. it's not). But I can't find any infromation about IAFEF. Someone can point me to information about this component ? I'm quite inexperienced.Edit: Just found another thread here where it seems that also IAFEH is the Mp2159GJ-z. It seems to me that IAFEF, IAFEE, IAFEH are all the same. I'm going to buy them and try to cheange the faulty component anyway. Just love a confirmation.update 1: the Mp2159GJ-z is not equivalent to IAFEF.

author: jpm1680
author_rank: Newbie
timestamp: December 01, 2021, 05:06:24 pm
content: Quote from: braianokonnor on March 05, 2019, 04:34:59 amI know this is an old thread, but I wanted to get Braian some resolution on this.I just opened up my neighbor's 2i4, and it had the same issue as yours. L12 getting super hot. Unfortunately my finger is not sensitive enough to detect the other hotspots on the board, so I borrowed a thermal camera from someone.The right spots are the inductors, as you already know about.I zoomed in on the left hotspot, and it's one of the HC4066AG multi-switch ICs.Without power, the other HC4066AG ICs had nominal resistance from the inputs (pins 1, 4, 8, and 11) and outputs (pins 2, 3, 9, 10) to GND (pin 7). This one had 2.4Ω on A and B inputs and outputs. While I expected anything connected to the shorted inductor to have minimal resistance to GND, the fact that both the input and the output were shorted made me suspicious. I removed the component, and sure enough, the pins measured 2.4Ω to GND without being mounted. And now the 2i4 is working as an output device. I've ordered a replacement part, and hopefully that will restore full functionality.

author: chanobass
author_rank: Newbie
timestamp: April 07, 2022, 10:06:41 pm
content: Great! Thank you very much! I'm missing the L5, and the one in light blue, I think it's the C137. Can you help me with the C137 please. Thank you very much!!