Author Topic: Siglent 1202X-E Fan Noise  (Read 2140 times)

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Offline Roger Need

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Re: Siglent 1202X-E Fan Noise
« Reply #25 on: December 26, 2018, 09:41:14 am »
Have any cold rooms you could run it in for a few minutes. May be able to figure out how things change with different temperatures.

The cold room is what helped me get to the bottom of it.  It started off much quieter than in my heated lab and it took much longer to reach max fan noise.   

Here is a link to a previous post on noisy fans in the SDS1104X-E and a fix...   https://www.eevblog.com/forum/testgear/siglent-1104x-e-noisy-fan-replacement/

In that post Bob Sava gives the part number of the fan. Here is a link to the specs.   http://www.szdosense.com/eng/products-detail.asp?cpid=177 A screenshot of the specs is below.   

I suspect the same fan was used in the initial release of the 1202X-E.   Anyone know the answer??  Is it the same fan in current production units?
 
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Offline tinhead

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Re: Siglent 1202X-E Fan Noise
« Reply #26 on: December 26, 2018, 10:30:07 am »
my SDS1204X-E (from around Oct 30th) have different fan, PAAD16025SL from Aavid Thermalloy, yeah even louder model :\

https://www.mouser.com/pdfdocs/Aavid-thermal-fans.pdf

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Offline Performa01

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Re: Siglent 1202X-E Fan Noise
« Reply #27 on: December 26, 2018, 10:31:36 am »
There are only 2 wires on this fan so they must be using voltage control, without feedback, to increase the fan speed and airflow. This is not a good design choice if different fan suppliers are used.  This may account for Tautech's observation that new units are less noisy. A different fan would not have the same CFM vs. voltage characteristics and might be less noisy for the same voltage.
Well, you should keep in mind that this is a low cost entry level device. Most DSOs are rather noisy and not many of them have any form of temperature control at all.

The solution might appear sloppy, but then the platform of the SDS1000X-E series is capable of monitoring the temperatures in critical components (SoC, FPGA, ADC, mainboard).  So a different airflow vs. voltage might affect the control characteristic - maybe even in a negative way - but at the end of the day, the fan will always get enough voltage to keep the temperature below the internally programmed threshold - if it is powerful enough in the first place, that is.
 

Offline Performa01

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Re: Siglent 1202X-E Fan Noise
« Reply #28 on: December 26, 2018, 10:35:08 am »
my SDS1204X-E (from around Oct 30th) have different fan, PAAD16025SL from Aavid Thermalloy, yeah even louder model :\

https://www.mouser.com/pdfdocs/Aavid-thermal-fans.pdf


Yes, SDS1004X-E models have at least one additional ADC, which is traditionally the hottest component in there. So I would not be surprised if a slightly more powerful (and louder) fan has been fitted.
 

Offline tinhead

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Re: Siglent 1202X-E Fan Noise
« Reply #29 on: December 26, 2018, 11:22:17 am »
Well, you should keep in mind that this is a low cost entry level device.

sure, on the other hand - based on my experience with Hantek gears (paying more = heatsink on ADC and better fan) - i thought it might be not bad idea to buy SDS1204X-E instead of cheating Siglent on the "license fee". That makes 230EUR diff for dealer, or 100EUR diif for Siglent, that's why expected better fan  :--


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Offline ct1bxt

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Re: Siglent 1202X-E Fan Noise
« Reply #30 on: December 26, 2018, 12:34:51 pm »
Hi,

my 1202x-E is quite after power ON. After that the fan increases sped, but nothing special.
My main complain is the power LED that starts blinking as soon as I connect the power cable. I would like a real switch instead.

Rodrigo
   
 

Offline StillTrying

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Re: Siglent 1202X-E Fan Noise
« Reply #31 on: December 27, 2018, 05:40:47 am »
I can't imagine how there'd be any fan speed increase without the humps at 750Hz moving quite a bit to the right.


« Last Edit: December 27, 2018, 05:42:39 am by StillTrying »
CML+  That took much longer than I thought it would.
 

Offline Roger Need

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Re: Siglent 1202X-E Fan Noise
« Reply #32 on: December 27, 2018, 06:01:00 am »
I can't imagine how there'd be any fan speed increase without the humps at 750Hz moving quite a bit to the right.

You can see in the time plot that the overall noise level is increasing and it was measured 10 cm. from the exhaust port.  So I believe the fan is increasing in speed as the internal temperature rises.  The "humps at 750 Hz." are probably due to case and grill resonance and the amplitude would rise as airflow increases.
« Last Edit: December 27, 2018, 06:11:11 am by Roger Need »
 

Offline Roger Need

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Re: Siglent 1202X-E Fan Noise
« Reply #33 on: December 27, 2018, 06:10:00 am »
The fan specs posted earlier got me to take a close look at the air vents on the SDS1202X-E.  In the photo below you can see that about 1/3 of the fan is blocked by the external plastic case.  This has a considerable effect on the effectiveness of the fan.

The effectiveness of a fan is based on two parameters.  The first is the volume of air that the fan can move per minute which is usually expressed in cubic feet per minute (CFM).  The second is the fan static pressure that can simply be described as the resistance pressure that the fan has to blow against in order to exhaust the air in the desired direction. If a fan is blowing against high resistance pressure (like fan blockage) it requires more energy and delivers less air flow.   It also creates more noise.

The fan specs used in a similar scope are shown in the photo below.  It is clearly evident that the CFM of these small fans drops considerably as fan static pressure increases.  When the scope is cool the fan turns slowly and as heat is internally generated the voltage to the fan must be increased to increase airflow over the components inside.  Unfortunately, due to the the fan being blocked by the case and airflow resistance by the grill the fan must run at a higher speed, with more noise, than would be the case if the exterior plastic case had been designed to accomodate better venting. 

Changing the brand of fan would probably not result in lower fan noise with this case design due to the partially blocked fan exhaust.  I took a look at the SDS1104X-E photos and it does not appear to have much of the fan exhaust blocked.  Looks like a design oversight with the SDS1202X-E.  I highly doubt that they have retooled the case to get the lower noise output that Tautec posted earlier so one wonders how this was achieved.  Was it a change in the firmware algorithm for fan speed?

One possible modification would be to add a quiet inlet fan on the opposite side like the 1104X-E mod posted previously.  There is not much room due to the AC input connector.  A small fan would have to be used.

 

Online Fungus

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Re: Siglent 1202X-E Fan Noise
« Reply #34 on: December 27, 2018, 10:59:30 pm »
I can't imagine how there'd be any fan speed increase without the humps at 750Hz moving quite a bit to the right.

Maybe those are a resonance in the case or a hum caused by air flowing over the grille.

 

Offline nctnico

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Re: Siglent 1202X-E Noise Issues
« Reply #35 on: December 28, 2018, 12:11:21 am »
As mentioned to Roger via PM’s, I’m reasonably sure another member has added a series resistor to the fan to slow it some and reduce fan noise.
This topic would benefit from other owners experience if they would care to share what they’ve done.
There’s also adding rubber mounts to reduce resonant coupled noise........also mentioned by Performa01.
In my experiencel rubber fan mounts are a (well worth!) quick fix to take care of the low hum which couples/resonates into the casing. Getting rid of a high pitch wine is likely to need a different fan. As a rule of thumb the thicker the fan the less RPM it needs to move a certain amount air while producing the same pressure differential.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline Roger Need

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Re: Siglent 1202X-E Fan Noise
« Reply #36 on: February 09, 2019, 06:37:44 am »
I contacted Amazon and they sent me a replacement unit.  This one was manufactured in November 2018 - the other one was produced in February 2018.  A side-by-side comparison was interesting.  The level of white fan noise is about the same but there is no high pitched whine in the replacement unit.  I don't know if the whine is coming from the switching power supply or the the fan.

According to the utility menu has been a change in the hardware and I will be making a new post about that.
 
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Offline Dundarave

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Re: Siglent 1202X-E Fan Noise
« Reply #37 on: March 10, 2019, 04:28:15 pm »
As mentioned to Roger via PM’s, I’m reasonably sure another member has added a series resistor to the fan to slow it some and reduce fan noise.
This topic would benefit from other owners experience if they would care to share what they’ve done.
There’s also adding rubber mounts to reduce resonant coupled noise........also mentioned by Performa01.
In my experience rubber fan mounts are a (well worth!) quick fix to take care of the low hum which couples/resonates into the casing. Getting rid of a high pitch wine is likely to need a different fan. As a rule of thumb the thicker the fan the less RPM it needs to move a certain amount air while producing the same pressure differential.

Per Tautech's suggestion re: other's experience and nctnico's observation re: rubber mounts, has anyone actually taken steps to either replace the fan with a quieter one and/or added a series resistor and/or added rubber mounts? If so, I'd love to get the specs and sources for a replacement fan, rubber mounts & the resistor used.

I've got an SDS1104X-E (late-2018) that I'm very happy with, but my work area is very quiet, and I find myself turning off the scope when it's not being immediately used, which can be inconvenient at times, so I'd like to try to do something about it.  I checked out the May 2018 thread on the topic (i.e. Siglent SDS1104X-E noisy fan replacement, OP Bob Sava) but it discussed the fan being mounted on the "right side" of the scope, whereas my scope has the fan on the left side, so I wasn't sure if it was the same 1104 version. (Edit: I just realized the OP was looking at the scope from the rear as he was working on it, lol.)  He had added two fans...  I'm hoping for a less complex solution, i.e a simple combo of fan swap/resistor splice/rubber mount.

Has anyone done any fan mods for an 1104X-E or similar that they could share the details & parts sources of?

Thanks - :-+
« Last Edit: March 10, 2019, 05:05:47 pm by Dundarave »
 

Offline tkamiya

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Re: Siglent 1202X-E Fan Noise
« Reply #38 on: March 11, 2019, 02:36:31 am »
I'm afraid OP will have to find his own "comfort zone".  No matter how quiet or loud it is to others or what decibel meter says, perception of loud/quiet is very individualized.

I have a certain condition that makes me extremely sensitive to sound.  Also, I have a "dip" in sensitivity on one ear.  To me, high pitch sound seem louder than lower pitch sound.  (think mosquito at night!)  In quiet place, even a little noise sound louder.  Funny, I have a noise cancelling headset.  It only cancels repetitive sound.  Using it is sometimes worse from perceptive point of view as very little non repetitive noise comes right through.  Sometimes 10 dollar ear muff from Home Depot works better.

Fans are cheap to replace.  I've been going through a few that irritates me.  That said, my Siglent is pretty quiet and barely audible.  Since the fan is on back side of it, you can also be creative and try to remove noise that bounces off of a wall behind it.  I am uploading a photo of part of my lab.  On it, you'll see black and blue foam I bought from Amazon cheap.  White bar across it is my lighting.  Those foams are  thin but effective in preventing sound bouncing.

Run higher voltage fan with lower voltage power is also possible.  Often times, slowing it down is a good solution.  Some computer type fans are amazingly quiet, yet enough air to be effective.
 


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