Has anyone else gotten shrill noise/whine on their Siglent SDS1104X-E?

[Coldblackice]

I bought my Siglent SDS1104X-E just under a year ago. Recently, however, I've been noticing a shrill, high-pitched whine coming from it. I can't tell if it's from the fan or something else as it's hard to pinpoint, but it sounds almost like coil whine. Has anyone else experienced this?

It's not blaring or anything, and I wouldn't be surprised if some people couldn't even hear it, but it's enough that I can't even focus because of it, like nails on chalkboard. It'd be one thing if it was just a loud fan, I can make do with that. But the high-pitch shrill of this feels like my ears are being continuously waterboarded with sound.

I've tried moving the scope to different power outlets/circuits, isolating it, swapping power cables (knew this wouldn't help anything, just checking off boxes), and letting it run for a while hoping it'd go away after warming up -- all to no avail.

Anyone else experienced this? Any suggestions? I suspect this may have to be a warranty servicing/RMA, which I'd rather not have to do, but I just don't feel I can get used to this sound.

[tautech]

Yes I've had to replace just one fan in the dozens I've sold.
My customer sent me a video where the squeal from it was plain and I sent on the video to Siglent and they supplied another fan no problems.
However it's an apparently rare event and they wanted me to take pics of the fan model to keep in their records so to be able to monitor if it was particular to that model fan.

It was just on a year old too and by the time I got another and was able to replace the noisy one the customer told me it had barely ever made a noise again. Go figure ! 

Contact Siglent in Ohio and send them a video and they will advise you the next course of action.

[hsquared]

Just wondering if you also had this fixed?

I bought a new unit through Amazon, and it had this high pitch sound.
This unit was hurting my ears within an hour of sitting near the scope.
Sound spectrum through phone app:
https://imgur.com/a/gR9PUXL

I contacted Siglent, and they said it's unusual. They said they would repair it if it's within 3 year warranty, but if it's from Amazon and within 30 days, to return through Amazon.

So I got a replacement unit from Amazon today. This second new unit has the same sound, albeit slightly quieter.. If it doesn't get worse, maybe I can put up with it..

[tautech]

Just wondering if you also had this fixed?

I bought a new unit through Amazon, and it had this high pitch sound.
This unit was hurting my ears within an hour of sitting near the scope.
Sound spectrum through phone app:
https://imgur.com/a/gR9PUXL

I contacted Siglent, and they said it's unusual. They said they would repair it if it's within 3 year warranty, but if it's from Amazon and within 30 days, to return through Amazon.

So I got a replacement unit from Amazon today. This second new unit has the same sound, albeit slightly quieter.. If it doesn't get worse, maybe I can put up with it..

Welcome to the forum.

I had another customer complain about the noise levels in his although it never worried him for a year or more until he shifted his lab into a smaller room at a new address. When he was next up our ways he called in and we placed a further 2 units side by side to check if his was abnormal and it wasn't.
I had my old SDS1104X-E in the mix and we opened it up to check if there were changes in the fans from early HW versions and there is. My old unit and his shared the same 12V 150mA fan whereas newer HW has a 110mA fan.
Noise levels are a little different however the newer fan is quieter but barely.

For giggles I stripped the fan grille from the chassis with sidecutters to check if there was some influence on noise from the grille....no significantly noticeable difference !

My conclusions if you must reduce noise are 3 options but as yet untried.
Replace with top quality fan.
Series resistor on fan supply to reduce speed.....careful experimentation for your climate/ambient temp required.
Rubber mount fan.

[hsquared]

Thanks for the welcome.

So I have two 1104, and one 1202 with me right now.

All three are basically new, and had their factory calibration within the last 6 months.

The 1202 has zero audible high pitch sound. Do you know if that is a different fan model, and if so what it is? I think I'd be willing to open my 1104 to replace the fan or slow it down if it'll remove the high pitch sound.(I'm in a room that is always around 70F/20C so would imagine I have some margin as far as heat/temp)

[tautech]

Thanks for the welcome.

So I have two 1104, and one 1202 with me right now.

All three are basically new, and had their factory calibration within the last 6 months.

The 1202 has zero audible high pitch sound. Do you know if that is a different fan model, and if so what it is? I think I'd be willing to open my 1104 to replace the fan or slow it down if it'll remove the high pitch sound.(I'm in a room that is always around 70F/20C so would imagine I have some margin as far as heat/temp)

Early SDS1202X-E used a different fan than current HW and in both cases are quieter than their 4ch cousins with late model SDS1202X-E being very quiet.
As alluded to before I don't believe SDS1104X-E grille design has a significant impact noise so IMO only the 3 options I mentioned earlier exist for addressing fan noise.
IMHO to match the OEM cooling design rubber mounting the fan should be attempted first as fan harmonics are possibly amplified by the chassis. If that didn't substantially reduce fan noise investigate fitting a Noctua fan with the same flow and pressure spec as OEM.
https://noctua.at/en/products/fan

A series resistor of course is a simple solution but detailed analysis of the correct value is required to provide sufficient cooling for your ambient temp however this solution will not properly suit others and certainly place reliability at risk whereas careful fan replacement and/or rubber mounting far less so.

Do come back and post your solution as it may help others with a sensitivity to fan noise.

[hsquared]

A few updates:
I opened up one of the 1104's and it has a 0.15A 12V fan.

I unplugged the fan, and the buzz/whine was much much quieter, but definitely still there (but would be zero problem for me if it was at this leevl). At this point I realized it might be the power supply coil whine, and it just gets more noticeable with higher load. So, I plugged in a 90Ohm load in place of the fan, and the buzz was back.

The sound starts after the scope powers on fully. While it's starting up and the fan is running, the buzz is not audible. So it's a combination of the scope load + fan load that makes it buzz.

I think it's the big inductor or the small one next to it, but can't exactly pinpoint it.

I tried a 130ohm load (simulating if I add ~50Ohm in series with the fan). The frequency of the sound went lower, but sounded about just as loud. So changing the fan or adding a series resistor probably won't help enough.

I added the rubber fan mounts, and also some diy rubber pads on the PSU pcb mounts. They didn't noticeably change anything. Then I added hot glue on the big inductor and smaller one next to it. That didn't help either..

I think one additional option is to remove the fan and use an external fan+power supply
Or 2) try to further sound dampen the entire PSU PCB/chassis

[tautech]

A few updates:
I opened up one of the 1104's and it has a 0.15A 12V fan.

I unplugged the fan, and the buzz/whine was much much quieter, but definitely still there (but would be zero problem for me if it was at this leevl). At this point I realized it might be the power supply coil whine, and it just gets more noticeable with higher load. So, I plugged in a 90Ohm load in place of the fan, and the buzz was back.

The sound starts after the scope powers on fully. While it's starting up and the fan is running, the buzz is not audible. So it's a combination of the scope load + fan load that makes it buzz.

I think it's the big inductor or the small one next to it, but can't exactly pinpoint it.

I tried a 130ohm load (simulating if I add ~50Ohm in series with the fan). The frequency of the sound went lower, but sounded about just as loud. So changing the fan or adding a series resistor probably won't help enough.

I added the rubber fan mounts, and also some diy rubber pads on the PSU pcb mounts. They didn't noticeably change anything. Then I added hot glue on the big inductor and smaller one next to it. That didn't help either..

I think one additional option is to remove the fan and use an external fan+power supply
Or 2) try to further sound dampen the entire PSU PCB/chassis

Very interesting and thanks for reporting back.
Did you try the stethoscope trick to identify exactly where the whine was coming from ?

I've handled a lot of these over the years and never heard this whine you describe.
When I get a chance I'll pull my old X-E apart again and look harder at the PCB.

[bson]

Scope the fan pins with a resistor in place, maybe the fan is PWM controlled and the noise comes from the fan controller?

[bson]

I've handled a lot of these over the years and never heard this whine you describe.

14kHz isn't that audible to most people... I know for certain I couldn't hear it.

[hsquared]

Scoped the fan, and it's 12V without PWM.

Yup, tried using a straw, as well as a longer vinyl tubing. I still can't tell.. I think it's near the bottom left of my picture where I put hot glue. I can hear it in the red area with the straw, but it seems to just vibrate and echo everywhere...

Maybe the hot glue finally completely hardened, but it's basically inaudible with the fan and inside the case.
However, it's a lot louder with no load now for some reason..
Also, the higher load actually sounds more quiet.

The frequency is lower according to my sound spectrogram app, compared to my first unit. (around 12-13kHz)
It also seems to be lower frequency with higher loads now too, so maybe that's why it's not as loud/piercing to my ears.


Oddly, using my camera app to record, I can't hear it in playback, even using my good speakers.

[tautech]

@hsquared
One more thing, how old are these units and what is the boot # count ?

[hsquared]

tautech, they were purchased new this month.
Both say hardware version 01-05
FPGA Version 2019-11-15

Startup # of times = 28 and 30

[Martin72]

I think it's the big inductor or the small one next to it, but can't exactly pinpoint it.

I know this problem from our selfmade coils.
We do a vacuum-glueing to them, so they are very quiet after that procedre.
What you can do is to glue the windings to each other and to the core, when it is not a air coil only.
The glue should be less elastic and temperature-stable.

[tautech]

tautech, they were purchased new this month.
Both say hardware version 01-05
FPGA Version 2019-11-15

Startup # of times = 28 and 30

Thanks.
Now bought to the attention of tech support at the factory where they can study your posts and hopefully work out a solution although what you report is unheard of AFAIK. They may know more about it.
Still it interests me as I know newer units use a different fan to early releases and latest fans have a lower current draw.
Maybe there are some faulty PSU's, IDK. 

[hsquared]

I think it's the big inductor or the small one next to it, but can't exactly pinpoint it.

I know this problem from our selfmade coils.
We do a vacuum-glueing to them, so they are very quiet after that procedre.
What you can do is to glue the windings to each other and to the core, when it is not a air coil only.
The glue should be less elastic and temperature-stable.

The big transformer has the copper foil wrapped around it, so a bit difficult to get glue inside.

Less elastic is better, compared to hot glue? I was thinking if I should use some simple GE Silicone II caulk I already have. But that is probably more elastic.

I was looking at maybe getting a different scope, as it's still bothering me... The SDS2000X plus looks really nice to me, and the 100MHz version isn't out of my budget. The teardown from November showed the same exact power supply as in my SDS1104X-E though
The SDS1202X-E is fantastic on this front, so I'm somewhat optimistic in finding a scope that won't bother my ears.

One new thing I noticed is I think I am picking up FM radio/TV noise.

With the probe connected to it's own ground clip, the noise gets better as I move the probe away from the scope, and worse when I move it towards the scope or towards the probe cable. It's also sensitive to me touching it. Whatever I do though, I can't get it below ~20mV ptp. Not sure if this is big or not...

I wonder if this could somehow also be modulating and getting into the power supply as 11-15kHz noise.

[tautech]

hsquared
I dismantled my SDS1104X-E to check the PSU for noise and of course there was none and just to make sure I disconnected the fan for a bit and noise was nothing, zip, nada, nil !
So I think you have a faulty unit and replacement of the PSU is in order so lodge a warranty claim.

My assumption is the transformer core/s are cracked or the clips that hold them together have failed somehow to let the E cores come apart slightly and resonate.
I also suspect it's the same PSU used in a previous model SDS1000X as that code is on the PSU sticker.

[hsquared]

hsquared
I dismantled my SDS1104X-E to check the PSU for noise and of course there was none and just to make sure I disconnected the fan for a bit and noise was nothing, zip, nada, nil !
So I think you have a faulty unit and replacement of the PSU is in order so lodge a warranty claim.

My assumption is the transformer core/s are cracked or the clips that hold them together have failed somehow to let the E cores come apart slightly and resonate.
I also suspect it's the same PSU used in a previous model SDS1000X as that code is on the PSU sticker.

Thanks, Tautech, for checking that. I will contact Siglent here in the USA then!

[hsquared]

An update:

Siglent North America said I can only return to Amazon since it's within 30 days, and they won't take it as a warranty.

I'll be just returning both my units to Amazon then. The hot glue came off quite easily haha.

I bought a 3rd unit from an authorized dealer, and it has the same sound. It doesn't bother me as much for some reason though, maybe because it is slightly higher frequency that would then possibly be closer to being out of my hearing range (15kHz, instead of 13-14kHz, though I'm taking my phone app readings with a grain of salt). Will try to use it for a few days first. *fingers crossed*

The calibration dates are all around the same time, so maybe they are the same batch? 9/26/2020 for the two through Amazon, and 9/25/2020 for the 3rd unit. The serial numbers separating the two Amazon units is off by 20, and the 3rd unit's serial number is 134 smaller. The SDS1202X-E that doesn't have any coil whine sound is 8/30/2020.

[tautech]

Interesting. Sorry you had to experience this nuisance. 

Not come across this before as I mentioned earlier and it seems Siglent is not the first to be afflicted with noise from a SMPS in a DSO:
https://www.eevblog.com/forum/testgear/agilent-oscilloscope-mso-x-2012a-audible-high-pitched-sound-and-hiss/

As I fire every unit up before sale if any have a whine in the PSU ......warranty claim here we come !
Thanks for the manufacture/Cal dates as they indicate what batch we need be wary of.

PM me the SN#'s if you don't mind.

[hsquared]

Yeah, quite unfortunate. I do want to like this product especially given the price and features it has, so hopefully it'll work out.
I PM'd you as well.

[tautech]

Yeah, quite unfortunate. I do want to like this product especially given the price and features it has, so hopefully it'll work out.
I PM'd you as well.

Received with thanks.
Going by their SN#'s I'll lay money they were all from the same production batch.
Yours are in this range: SDSMMFCQ4R5800 - SDSMMFCQ4R6000

My last stock were in this range: SDSMMEBQ4R5400 so produced well before the units you had.
More arrive next week....SN#'s unknown as yet.

Only time will tell if there's more out there giving problems too. 

[hsquared]

Just an update:
Returned to Siglent for warranty. They said it seems normal, and to get a refund from the distributor under their RMA number.

I guess I just need to search for a different model or brand now.

[tautech]

Just an update:
Returned to Siglent for warranty. They said it seems normal, and to get a refund from the distributor under their RMA number.

I guess I just need to search for a different model or brand now.

The one you covered the transformer with holt melt glue ? 

[hsquared]

The one I sent to Siglent hadn't been opened. They wouldn't take the hot glued one since it was from Amazon and not 30days yet, so I peeled off the glue and sent back to Amazon.. given how easily the glue came off, maybe that's why it wasn't effective for noise reduction. Both had basically the same audible whine sound to me.