Author Topic: Rigol DS1052E fan - removed! (Read 23941 times)

hacklordsniper · « **on:** February 17, 2011, 06:55:03 pm »

Hello,

im reading this forum many, but i don't post. Anyway i just tested our dear oscilloscope 24 h without fan! Working fine, LM317T goes up to 72 C which is somewhere almost safe. I will surely install a 10 dBA 1500 RPM fan, just to have at least some airflow. The unit is HW 58, produced on 10.02.2011.

Zero999 · « **Reply #1 on:** February 17, 2011, 07:11:51 pm »

Did you measure the ambient temperature?

Suppose it's in a cool 15^oC room, of course you'll be fine but what about a hot summer's day 35^oC, the LM317 might shut down.

hacklordsniper · « **Reply #2 on:** February 17, 2011, 07:26:39 pm »

Ups... i did not measure ambient temperature. In my room is 22 C now. I will measure it...

I think with silent fan, everything will be ok.

Scrts · « **Reply #3 on:** February 17, 2011, 07:49:27 pm »

Quote from: hacklordsniper on February 17, 2011, 07:26:39 pm

Ups... i did not measure ambient temperature. In my room is 22 C now. I will measure it...

I think with silent fan, everything will be ok.

Remember that if the outside of the chip is 72, the crystal itself temperature could be about 110-120.

sonicj · « **Reply #4 on:** February 17, 2011, 07:59:38 pm »

doh! i meant to post these like months ago. better late than never i suppose...

i have dB measurements around here somewhere, lol! anywho, i can here a mouse fart when its first powered up. after about 45 minutes the fan is singin pretty good, but nowhere near as loud as stock!
-sj

sonicj · « **Reply #5 on:** February 18, 2011, 02:49:56 am »

heres a link to the fan i used: vantec tf6025 via newegg
the quiet fan screws came from jab-tec: quiet fan mounts via jab-tec the red mounts felt stiffer than silicon. the black nexus mounts are definitely silicon.

the fan is temperature controlled so it starts out slow and speeds up as needed.
specs:
dual ball bearing
19-33.5 dBA
1900-4200 RPM
9.9-24.2 CFM

prior to ordering the vantec fan, i tried a few different resistors in series with the stock fan. i think i settled on 20? 2watt as a good value for airflow vs noise. it was nowhere near as quiet as the vantec, but much better than stock! i personally think the stock fan is a cheap POS and overkill for the application. anywho, 5 months on the vantec mod and no noticeable ill effects.

ohh yea, one more option is to use a 60mm to 80mm fan adapter. there are a lot more quiet 80mm fans on the market than 60mm. may want to check clearance if you go this route. jab-tec has a good selection and excellent pricing on this sorta stuff. i highly recommend!
-sj

hacklordsniper · « **Reply #6 on:** February 18, 2011, 03:07:29 am »

Quote from: Scrts on February 17, 2011, 07:49:27 pm

Remember that if the outside of the chip is 72, the crystal itself temperature could be about 110-120.

Its a good reminder. However today i will search stores to find a silent fan and to a test again. Im surely not going to put the stock fan back inside, since its really too loud. I have measured that there exists some kind of fan control, since the voltage varies from 9.5 V to 12 V depending on the temperature of the device (i still did not find out where the temperature is measured).

The only major problem is the 7805, squeezed between then PSU connector and fan connector without any heatsink, and its seriously overheating. Im planning to unsolder it, and insert a new one with a heat sink.

Simon · « **Reply #7 on:** February 18, 2011, 07:34:20 am »

one could slow down slightly the current stock fan, it is fairly defening and dave measured it at 60dB when he compared it to the new agilent

alm · « **Reply #8 on:** February 18, 2011, 12:41:14 pm »

Fans are relatively expensive, so it's unlikely to be superfluous. I would be careful with reducing airflow (which is necessary if you want less noise) without doing a careful analysis. Some components (eg. capacitors) may be more sensitive than others, they can be heated by other components. Maybe they need to limit the temperatures of some devices to meet spec (everything has a tempco). If the fan speeds up, that's a sign that their target temperature was actually exceeded.

the_raptor · « **Reply #9 on:** February 18, 2011, 01:27:25 pm »

Hasn't someone posted a mod to install a larger (therefore quieter for the same airflow) fan in the DS1052?

alm · « **Reply #10 on:** February 18, 2011, 02:40:47 pm »

Quote from: the_raptor on February 18, 2011, 01:27:25 pm

Hasn't someone posted a mod to install a larger (therefore quieter for the same airflow) fan in the DS1052?

I believe you're correct, that's actually a way to improve noise without sacrificing airflow. Note that a fan adapter (to adapt a smaller hole to a larger fan) defeats most of this advantage, because it introduces extra impedance (less airflow) and turbulence (noise). The extra space between the metal case and the fan also decreases effective air flow.

One solution is to get another piece of equipment that produces even more noise. I've also been bothered by the fan noise from my scope and function generator, but as soon as I turn on my lab supply with fan, they don't bother me anymore

.

hacklordsniper · « **Reply #11 on:** February 18, 2011, 02:43:35 pm »

I have managed to install a small heatsink on 7905, i hope it will help too. All fans i could find in markets in these part of world were:

REVOLTEC AIRGUARD 60X60
19.99 dBA, 2500 RPM, 20.92 m3/h

Xilence Red Wing 80x80
15 dBA, 1500 RPM, 32.85 m3/h

Arctic F8 PRO 80x80
20.00 dBA, 2000 RPM, 47.6 m3/h

I think i will put some of the later two.

saturation · « **Reply #12 on:** February 18, 2011, 03:43:07 pm »

Yes, fully concur with alm's analysis, I'd be concerned about whether Rigol really engineered a certain cfm as necessary to maintain the integrity of its components. My cursory analysis based on the tear downs we've all seen, and as you noted in the LM7805, it maybe some parts may not be as well ventilated as it best could be. You've found the PSU chip, is there anything else that could heat up more than needed?

When I use the 1052E, its pretty much on all day, so it reaches its stable operating temperature relative to ambient. I also engage the screensaver, FWIW, does anyone know if its compact fluorescent or LED backlit?

Lastly, when push comes to shove, heat is worse than being cool [but within operating spec, not frozen!] as far as component longevity and stability is concerned, so I'd err on being cool and noisy than warm and quiet.

Quote from: alm on February 18, 2011, 12:41:14 pm

... I would be careful with reducing airflow (which is necessary if you want less noise) without doing a careful analysis.

Simon · « **Reply #13 on:** February 18, 2011, 03:59:43 pm »

Quote from: alm on February 18, 2011, 02:40:47 pm

Note that a fan adapter (to adapt a smaller hole to a larger fan) defeats most of this advantage, because it introduces extra impedance (less airflow) and turbulence (noise). The extra space between the metal case and the fan also decreases effective air flow.

not neccesarily, I work for a radiator company and the adapter is commonly known as a shroud or cowl and it's job is to channel the air, if your just slapping an 8cm fan in front of a 6cm hole you are wrecking havock with airflow as air will hit the "wall" and just flows randomly around as it tries to get out in competition with the air coming straight from the fan inline with the hole. A proper shrould will gently chanel all of the air in the right direction.

Similar shrounds were used to adapt 8cm holes on computer cases to the 6cm fan on CPU heatsinks.

hacklordsniper · « **Reply #14 on:** February 18, 2011, 05:55:03 pm »

Ok, s o did extract many of temperature testpoints, analyzed all with replacement fans and original fan, run the thing for hours... Revoltec AirGuard is perfect, the temperature deviations from original or replacement fan are 1-2 C in worst cases. Also installed a small heatsink on 7905 and it stopped the heating almost completely. Here is a few pictures, i will leave the rigol running next 24 hours...

Pictures... http://hacklordsniper.com/Arhiva_projekata/Projekt_(16).html

Next project, Rigol DG1022 and Weller WX2 teardown

alm · « **Reply #15 on:** February 18, 2011, 07:53:45 pm »

Quote from: Simon on February 18, 2011, 03:59:43 pm

Quote from: alm on February 18, 2011, 02:40:47 pm
Note that a fan adapter (to adapt a smaller hole to a larger fan) defeats most of this advantage, because it introduces extra impedance (less airflow) and turbulence (noise). The extra space between the metal case and the fan also decreases effective air flow.

not neccesarily, I work for a radiator company and the adapter is commonly known as a shroud or cowl and it's job is to channel the air, if your just slapping an 8cm fan in front of a 6cm hole you are wrecking havock with airflow as air will hit the "wall" and just flows randomly around as it tries to get out in competition with the air coming straight from the fan inline with the hole. A proper shrould will gently chanel all of the air in the right direction.

Similar shrounds were used to adapt 8cm holes on computer cases to the 6cm fan on CPU heatsinks.

Yes, just using a larger fan on a smaller hole is worse, but the advantage of a larger fan + adapter over a smaller fan is debatable, and sometimes (small fan at low speed) not worth it. I'm sure it depends on a lot of factors including impedance, static pressure and air speed: I'll leave a proper analysis to someone else.

Quote from: alm on February 18, 2011, 02:40:47 pm

The extra space between the metal case and the fan also decreases effective air flow.

This comment referred to the Rigol mod by the way, not the fan adapter.

Simon · « **Reply #16 on:** February 18, 2011, 08:06:51 pm »

well at work in air conditioning units we turn air 90 degrees if we feel like it, this is not done simply with a 90 deg bend but with a specially constructed bed that has "parallel" fins inside to channel the air in the desired direction, providing your not trying to force air at a sharp angle and you have the pressure behind it you can change the direction without too much loss. I would think a shroud with less than a 45 degree angle will do no harm, of course this means the fan has to receed into the case to make room for the shroud, then again you also have the pressure impedence of trying to get air from a 50 sq cm fan through a hole of 28 sq cm and if you consider the "guard" over the hole your probably looking at 14 sq cm so (and I'm guessing as i'm no expert) your loking at a pressure increase of 3 times. Yes the larger fan will shove more air but can it put enough pressure on or will the resistance just put you back to square one.

Idealy I'd cut the hole right out and short of leaving it at that put a wire fan guard on which will impede the flow much less, choose a better quality 6cm fan and put temp control on it.

The other thing you can do for noise it turn the fan around, I know that it is noisiest from the blowing end, so why not blow into the scope rather than out ?

hacklordsniper · « **Reply #17 on:** February 18, 2011, 08:21:43 pm »

Quote from: Simon on February 18, 2011, 08:06:51 pm

The other thing you can do for noise it turn the fan around, I know that it is noisiest from the blowing end, so why not blow into the scope rather than out ?

I actually tried blowing air in but the fan was louder that way. This way the scope is completely silent, the most silent of anything on my bench. And also there is a a problem with blowing inside the dust and all contamination from air. And on the other hand you are keeping the hot air inside, just distributing it over less hot components, not a good way in my opinion.

Simon · « **Reply #18 on:** February 18, 2011, 08:26:29 pm »

well I don't know the blowing versus sucking theory but I'd guess dust could get in anyhow (just look inside your pc) but as the inlet is bigger than the outlet I guess the air flow in is reduce so not sucking in so much dust. The case vibrating from the fan possibly makes up much of the noise, there are holes all over the scope case, who knows whatthe air flow paths really are, in or out

alm · « **Reply #19 on:** February 18, 2011, 09:38:52 pm »

Quote from: Simon on February 18, 2011, 08:06:51 pm

well at work in air conditioning units we turn air 90 degrees if we feel like it, this is not done simply with a 90 deg bend but with a specially constructed bed that has "parallel" fins inside to channel the air in the desired direction, providing your not trying to force air at a sharp angle and you have the pressure behind it you can change the direction without too much loss.

Note that the amount of static pressure these kind of fans can overcome is almost zero, and the air speed in an AC is probably also much higher. Put something with a relatively high impedance (eg. heat sink) in front of a high-speed fan and the air will slow down, put it in front of a low-speed fan and almost no air will get through. This is not just proportional to the air flow.

Quote from: Simon on February 18, 2011, 08:06:51 pm

Idealy I'd cut the hole right out and short of leaving it at that put a wire fan guard on which will impede the flow much less, choose a better quality 6cm fan and put temp control on it.

Agreed. This will decrease turbulence (less noise and more air flow). Since it's a scope, EMI might be an issue, though.

Good temp control is an excellent way to reduce noise if it doesn't produce the same amount of heat all the time, as long as you can find a good place to measure the temperature. If it's blowing outward, measuring the temperature of the outgoing air might be a decent way, although finding the correct temperature may take some fiddling.

Quote from: Simon on February 18, 2011, 08:26:29 pm

well I don't know the blowing versus sucking theory but I'd guess dust could get in anyhow (just look inside your pc)

Sucking allows you to put a dust filter in front of the fan, since the air is only entering at one point. Of course this will create extra impedance the fan has to work against.

Quote from: Simon on February 18, 2011, 08:26:29 pm

The case vibrating from the fan possibly makes up much of the noise, there are holes all over the scope case, who knows whatthe air flow paths really are, in or out

Damping vibration can be done without impeding airflow, depending on how well it was designed, this may be an area that can be improved. Air flow paths will be completely different if you turn the fan around. Blowing at something tends to be much more focused and directional compared to sucking, so blowing in will mean more cooling for whatever is right in front of the fan, and less for the rest of the scope. I would expect the air flow to be specifically engineered around the current fan orientation (if they paid any attention to this).

Simon · « **Reply #20 on:** February 18, 2011, 09:51:55 pm »

Quote from: alm on February 18, 2011, 09:38:52 pm

I would expect the air flow to be specifically engineered around the current fan orientation (if they paid any attention to this).

to be honest I doubt they did, they just slapped a fan in there, I think it does more far more air than neccesary but then the air vents are all over the place, idealy the inlet holes should be around the hottest component heatsink on the PSU

sonicj · « **Reply #21 on:** February 18, 2011, 10:57:18 pm »

Quote from: hacklordsniper on February 18, 2011, 05:55:03 pm

Ok, s o did extract many of temperature testpoints, analyzed all with replacement fans and original fan, run the thing for hours... Revoltec AirGuard is perfect, the temperature deviations from original or replacement fan are 1-2 C in worst cases. Also installed a small heatsink on 7905 and it stopped the heating almost completely. Here is a few pictures, i will leave the rigol running next 24 hours...

Pictures... http://hacklordsniper.com/Arhiva_projekata/Projekt_(16).html

Next project, Rigol DG1022 and Weller WX2 teardown

that looks very nice! i have a few to220 heatsinks in my bin. i'll add one to mine.

beautiful work space you have there! im jelous!
-sj

sonicj · « **Reply #22 on:** February 18, 2011, 11:28:01 pm »

Quote from: alm on February 18, 2011, 07:53:45 pm

Quote from: alm on February 18, 2011, 02:40:47 pm
The extra space between the metal case and the fan also decreases effective air flow.
This comment referred to the Rigol mod by the way, not the fan adapter.

i believe you are mistaken... the gap is actually a carefully engineered convection enhancing airflow resistance counterpoise™.

-sj

the_raptor · « **Reply #23 on:** February 19, 2011, 05:44:04 am »

Quote from: hacklordsniper on February 18, 2011, 08:21:43 pm

Quote from: Simon on February 18, 2011, 08:06:51 pm
The other thing you can do for noise it turn the fan around, I know that it is noisiest from the blowing end, so why not blow into the scope rather than out ?

I actually tried blowing air in but the fan was louder that way. This way the scope is completely silent, the most silent of anything on my bench. And also there is a a problem with blowing inside the dust and all contamination from air. And on the other hand you are keeping the hot air inside, just distributing it over less hot components, not a good way in my opinion.

What? If you raise the internal pressure by sucking air in then some internal air HAS to leave the enclosure to equalise the pressure. Also the hot internal air will rise compared to the cooler external air. This is why PC's etc commonly have one fan low down in the case sucking air in and other fans higher up blowing air out.

Also a fan sucking air in eliminates the problem of dust entering through "vent" holes due to the internal pressure of the unit being lower than that of the atmosphere (my PC gets dust coming in through the CD drive area).

Simon · « **Reply #24 on:** February 19, 2011, 08:28:08 am »

yea I went mad once on pc fans and every crack in the case became a dust collector, even now with a 12cm PSU fan and an 8 cm case fan the inlet grill acts as a dust filter, I take it to work now and then and give it a blast of compressed air


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Author Topic: Rigol DS1052E fan - removed! (Read 23941 times)

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