Teardown, Repair & Analysis of a R&S FSEK 20Hz - 40GHz Spectrum Analyzer - Page 1
Forum section: electronics / repair

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 26, 2019, 01:52:32 pm
content: You can watch it here: [51 Minutes]youtu.be/oi4ipg9qHR4

author: coromonadalix
author_rank: Super Contributor
timestamp: August 26, 2019, 02:16:29 pm
content: I would correct your first thread title ---> 40GHz SpectrumAnalR&S ??

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 26, 2019, 02:47:44 pm
content: Quote from: coromonadalix on August 26, 2019, 02:16:29 pmDamn it! This is because of character limit on this forum. I didn't notice it when I pasted it.

author: thinkfat
author_rank: Unknown
timestamp: August 26, 2019, 02:51:14 pm
content: YES!! :-)I was already waiting for my monthly fix of RF repair footage :-) That will do nicely :-)

author: YetAnotherTechie
author_rank: Regular Contributor
timestamp: August 26, 2019, 04:35:28 pm
content: I have a similar unit, but with much worse screen and filter, and i have seen the condition in others too. The polarizer film in front of the lcd degrades, wrinkles and oozes a liquid, but the glass is not broken, it's the film. i believe this attacks also the mesh in the shield. This polarizer fault happens a lot on widescreen tv's, so there's a market for replacement polarizer film on ebay. I'm surprised you didn't have the issue in yours, maybe you didn't notice? I also bought mesh, optically clear glue, and acrylic, to rebuild the filter screen because i couldn't source one for less than 200eur. Were did you get yours, and how much it cost?Thanks for all the videos, you're great teacher!

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 28, 2019, 05:22:54 pm
content: Quote from: YetAnotherTechie on August 26, 2019, 04:35:28 pmYou are welcome.

author: DaJMasta
author_rank: Super Contributor
timestamp: August 28, 2019, 08:05:01 pm
content: A really nice repair! Of course it's good to see the equipment and analysis of it (and I was just wondering why they'd use a YIG filter in a microwave counter only a few weeks ago), but you sort of lucked out in a way with the faults. Component level, in depth and needing analysis and low-level knowledge, but no impossible to obtain parts - I think it makes for a good repair video.

author: eb4eqa
author_rank: Regular Contributor
timestamp: August 28, 2019, 09:32:19 pm
content: Hi,Can you tell us where you got the mesh and the glue? Or at least who makes them?Thank you,Roberto EB4EQAWww.rbarrios.com

author: Hugoneus
author_rank: Frequent Contributor
timestamp: August 29, 2019, 08:55:11 pm
content: Quote from: eb4eqa on August 28, 2019, 09:32:19 pmThere was no glue involved. I got a replacement screen from eBay.

author: eb4eqa
author_rank: Regular Contributor
timestamp: August 29, 2019, 09:44:18 pm
content: Yes, I'm sorry Shariar, I know... My question was for YetAnotherTechie, just forgot quoting...Please keep doing what you do, there is great value.Roberto EB4EQAwww..rbarrios.com

author: CrazyTiger
author_rank: Regular Contributor
timestamp: August 31, 2019, 09:55:25 am
content: Here is a fun trick for the FSEx series, measure the DANL by terminating the input of the spectrum analyzer with a good 50 Ohm load, than measure again after cleaning the IF filter board, you will easily notice close to 6 dB lower noise level after the cleaning.

author: YetAnotherTechie
author_rank: Regular Contributor
timestamp: September 03, 2019, 03:23:33 pm
content: Quote from: eb4eqa on August 28, 2019, 09:32:19 pmI got it from "The Mesh Company (Warrington) Ltd"in the UK#100 Mesh - 0.22mm Aperture -- 0.03mm Wire Diameter - -Copper 99.99% - Woven Wire -Open Area 78%Far better prices and quality than anything on the *bay.The glue is from the *bay, TP-2500 "LOCA" opticaly clear glue, UV curing, used for fixing cell phones.2x 1.5mm A4 Clear Perspex Acrylic Plastic Plexiglass 210mm x 297mm SheetI haven't finished or build the repair screen. I haven't had time yet.There are a couple of unknowns, first, to me the mesh inside the good parts of the original shield looked oxidized , i.e, the wires looked nearly black. I guessed this was made on purpose to make the image look better, so i investigated some techniques to oxidize the mesh.However on Hugoneus video the mesh looks not oxidized, maybe even golden?My second concern was that i believe the mesh will be filled with air bubbles once i pour the glue, and therefore it would need vacuum degassing after pouring, but i lost access to a vacuum pump system.Third note is, the mesh has to be in a rotated plane compared to the screen, is not parallel to either side, otherwise you get moire patterns. For LCD displays either 17°, 35° or 45°, i don't remember now which.https://hollandshielding.com/Mesh-foil-for-window-shieldinghas more info, great product, defence budget prices.For the attachment, i planned to cut one sheet of the acrylic a bit smaller, bend the mesh upward, coat the side with graphite conductive spray, and then copper plate.A lot of work, but unlike Hugoneus i couldn't come up with the magic words to find a source for parts...When i do the fix, I'll post pictures here

author: hafrse
author_rank: Regular Contributor
timestamp: February 09, 2020, 08:54:34 pm
content: Quote from: CrazyTiger on August 31, 2019, 09:55:25 amwhat kind of cleaning ? dust inside the IFS board or spraying connector pins?Thanks

author: CrazyTiger
author_rank: Regular Contributor
timestamp: February 12, 2020, 01:42:03 pm
content: Quote from: hafrse on February 09, 2020, 08:54:34 pmThis IF filter board is very sensitive to dust, in fact, the side of the board has holes that draws dust to the board in time. Usually, I vacuum clean the board(both the covers open) then proceed to clean the board with IPA. I would suggest taking a before and after of the DANL normalized to 1Hz so we can compare the result.A lower DANL is important when you want to measure a very low-level signal in ranges of -120dBm and lower.

author: hafrse
author_rank: Regular Contributor
timestamp: February 12, 2020, 08:20:04 pm
content: Quote from: CrazyTiger on February 12, 2020, 01:42:03 pm