Agilent 34410A Noisy fan - Page 1
Forum section: electronics / testgear

author: jstarr
author_rank: Regular Contributor
timestamp: July 12, 2014, 02:38:32 pm
content: I just bought this from Ebay and it works beautifully but the fan is noisy and the speed (by its sound) appear somewhat irregular. Oddly, if I put one of my fingers partly over the intake (about 1/4 of the intake) the fan speed and sound becomes quiet and regular. Any suggestions or should this be my first Tear Down !!john

author: engineer_in_shorts
author_rank: Regular Contributor
timestamp: July 12, 2014, 10:29:22 pm
content: Bearings?

author: LA7SJA
author_rank: Regular Contributor
timestamp: July 26, 2014, 07:00:52 am
content: The 34410-68502 (replaced bye 34410-68503) Assembly-Fan should be replaced.http://www.home.agilent.com/myagilent/faces/partDetail.jspx?partNumber=34410-68503&imageStatus=YESJFG

author: HighVoltage
author_rank: Super Contributor
timestamp: July 26, 2014, 08:46:02 am
content: I have installed low noise Papst fans in almost all my instruments that made too much noise.Papst makes them with internal thermistors on a little cable and you can place this sensor on the most heated part of theinstrument (heatsink) and the airflow will increase when needed. I have been doing this for years and never had any heatproblems with any Agilent instruments

author: engineer_in_shorts
author_rank: Regular Contributor
timestamp: July 26, 2014, 09:23:34 am
content: Quote from: HighVoltage on July 26, 2014, 08:46:02 amHi,I am interested in these. Do you have some part numbers or links to these products?

author: HighVoltage
author_rank: Super Contributor
timestamp: July 27, 2014, 12:21:03 pm
content: Quote from: engineer_in_shorts on July 26, 2014, 09:23:34 amSure.I just bought a broken Agilent E3640A PSU and it has a noisy fan too.When I replace it, I will take some pictures and write down the part numbers of the fan I will be using.

author: engineer_in_shorts
author_rank: Regular Contributor
timestamp: July 27, 2014, 01:37:00 pm
content: i think i have found it, page 14 on this PDF:http://www.ebmpapst.us/media/content/products/downloads/DC_fans_specials_2011.pdf

author: rob77
author_rank: Super Contributor
timestamp: July 27, 2014, 03:02:49 pm
content: the best way is to replace the fan, but while your replacement arrives , you can "fix" the old one.remove the fan from the equipment, disassemble the fan to the level needed to uncover the bearing (cheaper fans got only a sticker protecting the bearing) and add few drops of silicone oil to the bearing. it will become quite after this for few weeks/months - depends on the run-time.

author: SeanB
author_rank: Super Contributor
timestamp: July 27, 2014, 03:06:51 pm
content: Not silicone oil, but a drop of plain car engine oil works well. 0W15 synthetic oil works the best.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 27, 2014, 03:14:52 pm
content: Quote from: SeanB on July 27, 2014, 03:06:51 pmInteresting, that you tested this.I also have used high quality silicone oil for this kind of work but I never tried automotive synthetic oil.The fan noise not only comes from the bearings but also from the airflow and geometry and of course the speed.Getting a speed regulated fan makes all the difference in the world.I had the same on a LeCroy oscilloscope.That fan was so noisy, it was kind of torture, sitting next to it.LeCroy advised against the changing of the fan and I did it anyways and it worked out perfectly.Now the LeCory scope is as quiet as my new Agilent scope.

author: HighVoltage
author_rank: Super Contributor
timestamp: July 27, 2014, 03:26:48 pm
content: Quote from: engineer_in_shorts on July 27, 2014, 01:37:00 pmI just looked through my boxes and found the right one for the Agilent E3640A PSUIt is the PAPST Type 612MIThis one is 25,3 mm thick and 60 x 60 mm outside dimensionsSee enclosed pictures. Right next to the cable is the Thermistor for this fan.I have installed this PAPST type fan in several Agilent PSU and never had a problem with them.

author: rob77
author_rank: Super Contributor
timestamp: July 27, 2014, 03:29:57 pm
content: just one note regarding the oil... i'm sure the engine oil (virtually any lubricant) will work. but i'm using silicone oil because of it's properties:1. non corrosive2. clean , transparent and odorless3. it's a fairly good lubricant4. it's not conductive

author: SeanB
author_rank: Super Contributor
timestamp: July 27, 2014, 04:05:26 pm
content: I have done a fair number of fans where you could not replace them easily ( cost, availability and lead times) and the drop of oil worked for a long period, often months or years. Silicone oil is not the best lubricant in a bearing, as it tends to polymerise with time and with temperature, turning into an abrasive. As well the breakdown product is silicon dioxide, AKA sand. Mixed with carbon based oil and you get as a breakdown product silicon carbide, or grinding paste.The engine oil is light enough to lubricate, but thick enough that it will stay put in the bearing, providing a nice hydrodynamic film to reduce the friction between the sleeve and the shaft. It likely is also the original oil as well. Oilite bushes are typically prepared during manufacture after sintering by dumping them hot into hot oil which both cools them and impregnates them with oil. A lot these days seem to be made from leaded steel powder pressed into a bush then sintered, must be cheaper than bronze or brass powder.

author: rob77
author_rank: Super Contributor
timestamp: July 27, 2014, 05:03:06 pm
content: agree with all you wrote... but think of the plastic sleeves and the engine oilsilicone oil is used for lubrication of small parts (low temperature, low stress) surrounded by plastics for a good reasonthe engine oil is designed to lubricate metal parts in a high temperature environment, it might easily contain additives which are aggressive to the "low quality" plastic used in electronics.and last but not least - who has some engine oil handy in his lab ? if someone is doing machining along with electronics, then he might have some cutting oil or even engine oil handy.. but otherwise...

author: SeanB
author_rank: Super Contributor
timestamp: July 27, 2014, 05:24:43 pm
content: Engine oil is quite common as a lubricant, used for bushes on open switches in older equipment. There you just need a drop, so I use a 5ml syringe to keep it around. I also keep some synthetic grease around for the same reason. It makes a very nice reconstitutor for dried up thermal paste if you just are taking a part off and putting it back.

author: David Hess
author_rank: Super Contributor
timestamp: July 28, 2014, 03:17:36 am
content: I try to avoid silicon oil because it tends to creep.For fans bearing my current favorite oil is heavy gear oil like you would use in a transmission or differential. Over the past couple years, the worn fan bearings I have used it on have more than doubled their operating life without incident and are still going.QuoteI keep a couple of small clearly labeled plastic dispensing bottles with needle tips for things like contact cleaner and lubricant (MG Chemicals 801B), gear oil, light machine oil (LPS 2 or similar), flux (Kester 1544), Copper Nu, etc.

author: SeanB
author_rank: Super Contributor
timestamp: July 28, 2014, 04:50:23 am
content: Lubricants I keep at work are vacuum pump oil, 3 different refrigerant oils, 2 different compressor oils, 2 different gearbox oils and then greases, one synthetic food grade and 2 different greases. A small amount of moly grease as well along with tacky wheel bearing grease for odd uses. They are pretty useful, though I do tend to buy them in 20l drums.

author: Odd
author_rank: Regular Contributor
timestamp: April 16, 2023, 05:16:47 am
content: Fan in a multimeter? ( 34410A ) - that's a first ... what's the crazy reason for such requirement?also: can anyone suggest a suitable, silent, replacement specifications?

author: HighVoltage
author_rank: Super Contributor
timestamp: April 16, 2023, 10:12:34 am
content: Just install aPapstSUNONfan of the same size and add a 100 Ohm series resistor in the supply cable to slow the fan down a little. I have done this on every 34410A that I have / had.

author: Odd
author_rank: Regular Contributor
timestamp: April 16, 2023, 06:23:23 pm
content: can you please tell me the papst fan model you have used for 34410A ? (I'd like to avoid disassembly just to figure out the dimensions and voltage & wattage/current)

author: RolandK
author_rank: Regular Contributor
timestamp: April 16, 2023, 08:20:34 pm
content: The 34410A / 34411A seem to have 30 / 10 mm fans.The 34465A / 34470a seem to have 40 / 10 mm fans. Both just measured on the backside.The E3449a seems to have 80 / ? mm fans.In thehttps://www.ebmpapst.com/content/dam/ebm-papst/media/catalogs/products/Catalog_Compactfans_US_en.pdfis only a 40 / 10 mm fan, no 30 /10. So no luck with this.

author: HighVoltage
author_rank: Super Contributor
timestamp: April 17, 2023, 10:17:47 am
content: Quote from: Odd on April 16, 2023, 06:23:23 pmIt has been too long since I did this mod.I just looked at my notes, this was not a Papst fan.I used Papst fans for other Agilent gear.The fan you need for the 34410A and 34411A is a 12V 35x35x10mm.The model that I installed was a:Sunon MF35101V1-1000U-A99 Axial fan 12 V DC 12.24 m³/h (L x W x H) 35 x 35 x 10 mm

author: RolandK
author_rank: Regular Contributor
timestamp: April 23, 2023, 07:34:09 pm
content: In my 34411a with serial number starting MY48 is a 1204KL-04W-B40 12V DC 0.1A from NMB-MAT (Minebea-Matsushita) which is 30x30x10mm.Did they change the size, e.g. in later versions? Or did you modify the fan-mounting with a drill and dremel?

author: HighVoltage
author_rank: Super Contributor
timestamp: April 23, 2023, 09:19:42 pm
content: Nothing was changed, definitely not with a dremel.I am traveling right now. When I am back, I will open one instrument and take some pictures.

author: RolandK
author_rank: Regular Contributor
timestamp: April 25, 2023, 01:51:45 pm
content: You had the same fan, here are your pictures:https://www.eevblog.com/forum/repair/agilent-34410a-repair-attempt-of-2-dead-meters/msg820491/#msg820491i ordered now sunon HA30101V3-1000U-A99

author: Odd
author_rank: Regular Contributor
timestamp: May 14, 2023, 12:50:05 pm
content: After ordering and receiving a 35x35x10 Sunon, I discovered that mine too had the NMB-MAT 12v 0.1A fan (30x30x10mm).The fan supply is not properly regulated and was something like 13.2v with the fan connected.I added a 330ohm resistor in series, which made it work nice and quiet at about 6 volts or so.

author: HighVoltage
author_rank: Super Contributor
timestamp: May 14, 2023, 02:07:48 pm
content: Nice that you confirmed the 35x35x10 mmI just opened one of my 34410A and looked at the fan that I had installed many years ago with a 100 Ohm series resistor.Here are some pictures

author: Odd
author_rank: Regular Contributor
timestamp: May 14, 2023, 03:57:20 pm
content: !! no no no !!I did order, and received the 35x35x10 fan - but mine was a 30x30x10 ! (as somebody posted earlier.)Yours has a duct that reduces the 35x35 screw distance to the size of 30x30.