Repair : Rohde&Schwarz SMT03 5kHz-3GHz siggen - Page 1
Forum section: electronics / repair

author: TiN
author_rank: Super Contributor
timestamp: May 23, 2014, 12:17:18 pm
content: Got this one around 8 month ago, fixed it and used it, but last week it got same fault as last time, so teardown a little again to temporaryfixup.Anyone into some solid-made german engineering SG?Guesses what was faulty are welcome.Time to repair: 10 minutes.

author: VK5RC
author_rank: Unknown
timestamp: May 23, 2014, 12:21:28 pm
content: Fuse?

author: kizzap
author_rank: Unknown
timestamp: May 23, 2014, 12:39:21 pm
content: Obviously you had to change out the hamster.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: May 23, 2014, 01:43:37 pm
content: Your wife thinks you spend too much time with this unit and she saw what you fixed last time?

author: PedroDaGr8
author_rank: Super Contributor
timestamp: May 23, 2014, 01:50:57 pm
content: Had to change the dilithium crystals

author: mcinque
author_rank: Unknown
timestamp: May 23, 2014, 03:16:52 pm
content: Electrolytics in the psu?

author: Vgkid
author_rank: Super Contributor
timestamp: May 23, 2014, 04:07:10 pm
content: As much this forum has hate for tantalums caps, a tantalum cap.

author: TiN
author_rank: Super Contributor
timestamp: May 23, 2014, 04:19:02 pm
content: QuoteBingo, we have a winner.PedroDaGr8 wins a prize - bunch of hi-res photos!I did not disassemble much, as I feel not comfortable messing with high-frequency stuff which I don't understandSo at this moment, just a repair photo set, not a teardown.And since now I can use my repaired camera to make timelapses, made one for R&S SMT03 battery fix as well.4K UHD resolution for detail---Ok, here are those pesky high-resolution slow-loading photos again...Front panel have nice soft-feel buttons and enormous size display (as for generator). Front display glass is metallized to shield internals as well!And no, it's not touch.Unit is pretty heavy and bulky, but shortBack have some coax connectors, RS232, GPIB and two medium noise fans.Let's turn it on to see what's wrong..Aha, looks like it have sick battery, just like old 7000-series TDSes from Tektronix...Self diags agree to that..Let's crack it open and try to fix..Nice robust chassis, modular construction. Well made, very clean and tidy design. There are empty slots for options. My unit is just basic configuration,so have lots of emptynessBottom side shows us backplane interconnect with few bodged wires ( not me , promise ).Output unit is 3GHz marked. All modules shielded from both sides and have coaxes running in and out.Main output is routed via rigid coax with SMA ports.Output attenuator. It clicks a lot when changing output in big stepsMore coax stuff..And main output, totally separate from front panel body/assembly.It's type N 50 ohm female type.But our suspect is not in high-frequency area/boards. Where is usually battery located? In digital processor area, near SRAM. And where is processor board?It's not here, it's on front panel module. So I will not touch any of that high frequency boards and go right after front panel..Uncrew 4 corners and here we have, solid metal shielded block with front panel, screen and digital board. Really easy to service.Take a look at attention to details. Even 2.54mm headers have special plastic locks to secure connection!Or rubber pads on ribbon cables entry holes on shield to prevent cutting cable by metal edge. Never see such things before!Remove back shield:AhaaaDelithium crystal detected, blue thingy bottom right near CPUWhich is Intel i960. Not a common guest in test equipment, I'd say.Some more chips with funny names, like comgate, orbit...And some ADI stuffOk, let's check battery voltage...0.93V, no good!Desolder batt of the board.Have nice cutout and standoffs for easy servicing. Jumper nearby connects positive terminal to board. Well thought!Battery itself (this photo is actually of original battery which I replaced when just got a unit):Solder new battery in and voltage check:Now assemble everything back and check.Unit boots fine, run self-diags:OK!OK!Battery passed and OK now.All errors and calibration was restored by unprotecting PROT1 LEVEL via entry of password "123456" and running VCO,FM calibration steps. All this is performed by internal operation,no need external calibrators or connections.And some information about unit:No errors in this system:So back in business

author: Towger
author_rank: Super Contributor
timestamp: May 23, 2014, 05:05:12 pm
content: Reading from the start it appears this is the second time the battery failed. The last time only 8 months ago??

author: TiN
author_rank: Super Contributor
timestamp: May 23, 2014, 06:08:31 pm
content: Yes, but previous battery was not new, I salvaged it from huawei FPGA networking board, which was likely already 5 or 8 years old.Sent from my One using Tapatalk

author: casinada
author_rank: Frequent Contributor
timestamp: May 23, 2014, 06:16:14 pm
content: Thank you for the teardown, now I know what I have to do to replace the battery on my SME02. It has been dead for a while but too lazy to order a new one. Just waiting to have a bigger parts list to order from Mouser.

author: Kjelt
author_rank: Super Contributor
timestamp: May 23, 2014, 09:40:06 pm
content: Ok otherwise you could have measured the current that the battery had to source.Anyway I have an old R&S 2.3GHz generator somewhere but i have no clue what to do with it. Where do you use it for? radio, tv, video?

author: TiN
author_rank: Super Contributor
timestamp: May 24, 2014, 10:03:40 am
content: I use it as a clock source for testing digital systems. It's a source for buffer chipset / differential clock generators, so I can test them on various clocks in range of few hundred megs.

author: wn1fju
author_rank: Frequent Contributor
timestamp: May 24, 2014, 12:52:51 pm
content: A funny (or not) story about the same R&S sig gen I have at work. When the battery died, I told our purchasing department to call up the R&S service center in Maryland (nearby) and order me a new battery. We were given a quote of $21, which, of course, is ridiculous seeing as I could pop over to Radio Shack and get one for less than $10. But since it was the company's money, not mine, I told the purchasing person to go ahead. She came back a few minutes later and told me that R&S had a minimum parts order of $100 - that would actually be the battery price. I got on the phone with R&S to argue and they simply would not budge. So I wrote a letter to the President of R&S in Germany and told him that I was the principal decision maker for all my company's test equipment purchases, and I would look elsewhere to Agilent, Tektronix, etc. the next time, as they don't charge $100 for a $10 battery. Needless to say, a brand new (free) battery and an apology letter (claiming they were changing their minimum order policy) arrived in the mail shortly thereafter.

author: bingo600
author_rank: Super Contributor
timestamp: May 24, 2014, 06:19:03 pm
content: @OPNice teardown & fix.But for me , i don't want any R&S equipment for my personal use.There are no schematics on the net , and their tech. department is totally silent , when writing to them as a "private"Wel i have a Rohde - Schwarz HARMONIC FILTERS ATS-OWThat i have been seeking info on the GPIB commands for since December.Never got any responce from R&S , neither Denmark , nor Germany.The box works fine with the front buttons though, but i'd like to be able to control it via GPIBI also got a R&S Power Meter NRDV 857.8008.02 - Dual Power meter , but that's only because the price was "grab it now" ....I already have a HP E4418B-EPM , that i had to perform the same operation on:https://www.eevblog.com/forum/testgear/hp-e4418b-epm-powermeter-battery-change/msg420607/#msg420607I'll go for Agilent anytime , as they are "releasing schematics etc" , when an instrument goes out of service.I think R&S make nice instruments , but they're my first choice due to their lack of support./BingoWho has an Agilent E4432B instead.