Repair Usb Audio interface Focustrite 2i4

[firstcolle]

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

[sarel.wagner]

My 2i4 also gone, got accidentiall blown up by 12v supply... ooops

[Richard Crowley]

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.

[firstcolle]

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.

[firstcolle]

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!!!

[Richard Crowley]

That is quite excellent.  Congratulations on a great outcome.  4066 are rather a jelly-bean part available everywhere for pennies.

[Rasz]

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!!!

out of curiosity, was it a lucky guess or was 74HC4066 boiling hot?

[firstcolle]

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..

[Airman]

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.

[thxsound1138]

Hi,

U38 is NCP303LSN09, and L5 is DLW21HN121.

Cheers.

[EHT]

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!

[thxsound1138]

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!

Hi,

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.

[DaJMasta]

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.

[gabrielcsr]

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.

[ElecSeb]

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 more http://www.resistorguide.com/resistor-smd-code/)

[gabrielcsr]

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

[psfm]

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 swapping

Kind regards,

M

[psfm]

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

[KhronX]

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 DAW

You 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? 

[KhronX]

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. 

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!

[braianokonnor]

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..

[wraper]

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.

Low voltage electrolytic cap going short is quite extraordinary occurrence. Going short (in low voltage circuits) usually means faulty semiconductor devices or sometimes MLCC.

[wraper]

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..

It 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.

[braianokonnor]

can someone help me whit some reference to check that voltages.. please.. no schematic on internet

[Countrypicker]

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?