3458A care and maintenance - fan filter media - requesting assistance - Page 1
Forum section: electronics / testgear

author: neverendingstudent
author_rank: Regular Contributor
timestamp: August 24, 2025, 10:01:24 am
content: Hi all. I recently joined the 3458A club and am wondering about fan filter media and internal temps. When I got the meter the carbon foam dust filter over the rear fan was disintegrating, so I removed it and looked around for something suitable as a basic dust filter with the absolute minimum airflow impact. What I came up with was a stretched-out bit of medical gauze - very thin and porous, but still providing surface area to catch dust. Blowing on my skin through it compared to without I could feel that there was very little impedance to airflow.I'm uncomfortable leaving it that way long term though. Looking it up, the nominal expected internal temperature for the 3458A is supposed to be 38C, but when I swap from the 'short' menu to the 'full' menu and select the TEMP? command I got 40.5C, then after I had a soldering / repair session with my office door closed and my soldering iron, desoldering gun, and large fume extractor all running my bench ambient temp showed at 24C (usually it's between 22 and 23C) - a couple hours after I was done and had opened everything back up I checked TEMP? again and got 40.9C. I don't think I'm comfortable with that.Ok, prelude done.First I tried ordering the thinnest carbon filter foam I could find. Didn't even try installing it - the foam is high-density and blatantly obvious it is nowhere near as porous as the original media I removed. Clear resistance to airflow when I blow on it (can't even call it blowing through it).I looked up the part in a service note here:https://docs.ampnuts.ru/eevblog.docs/HP_Agilent_Keysight/3458A/service/3458A-16.pdfQuote from that service note:"3458A MultimeterSerial Numbers: 0000A00000 / 9999A99999UA00000000 / US99999999The original 3458A fan filter (3150-0300) is no longer available. Thereplacement fan filter uses three unique parts.Parts Required:P/N Description Qty.03458-04703 plate/spacer 13160-4115 fan filter (foam) 13160-0483 fan grillle 1Situation:When replacing the original “one piece” 3458A fan filter (3150-0300) the above three parts will berequired. If the 3458A already has the “three piece” fan filter use the above list to identify any partsthat need to be replaced."I then looked up the foam part number and found it for sale through Keysight... for $53. That is a blatant ripoff, I am damn sure that foam material can be had for less than that. My question is, where do I get it or what filter material is an acceptable substitute?Keysight store link:https://www.agilent.com/store/en_US/Prod-3160-4235/3160-4235Thanks everyone!

author: Grandchuck
author_rank: Super Contributor
timestamp: August 24, 2025, 01:08:22 pm
content: I am using one like this:https://www.ebay.com/itm/376322705456?_skw=60x60mm+Fan+Filter&itmmeta

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 24, 2025, 04:28:17 pm
content: Keysight pricing for support or parts or calibration is..."special." Eh, their products too.

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: August 25, 2025, 01:11:17 am
content: any not very thick and not very dense foam will dojust take one that is not falling into small particles after very short time cause you will have a lot of residues cleaning other than that aboslutely any taken from computer case or something will doI seen few times that they replaced all that into some kind of very dense cloth alike filter composed from very thin material but in such case you need to have habit to clean in often and remember about that cause they are so good in filtering but become clogged very fast usually

author: neverendingstudent
author_rank: Regular Contributor
timestamp: August 25, 2025, 01:19:10 am
content: Quote from: Grandchuck on August 24, 2025, 01:08:22 pmThank you kindly! Out of curiosity, what do you get when you use the 'TEMP?' command? (after that 4hr warmup time that is)

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: August 25, 2025, 01:34:02 am
content: Quote from: neverendingstudent on August 25, 2025, 01:19:10 amyou may find this usefulhttps://opendcm.blogspot.com/2021/05/agilent-3458a-in-lab.html