Siglent Oscilloscope SDS2104X repair help - Page 1
Forum section: electronics / repair

author: Gaktyt
author_rank: Regular Contributor
timestamp: November 24, 2019, 05:19:37 pm
content: Hi.I unfortunately blew one channel on my scope with a bit of overvoltage, and now the trace doesn't appear at all. So where do I start?Does anyone have any experience with Siglent scope repair? Does anyone have any schematic? Does anyone know if the front-end is repairable or is it all just one big custom chip?Siglent quoted me €700 for the "repair" (which turns out is just a main-board replacement), and I have about €100 in shipping cost - which lands me just shy of €200 for a completely new scope including shipping. Unfortunately I can't afford the repair nor a new scope at the moment, so I really need to figure out a way of repairing it.Your help is much appreciated.Gaktyt

author: tautech
author_rank: Super Contributor
timestamp: November 24, 2019, 05:43:58 pm
content: Welcome to the forum.Dave's teardown shows the front end clearly so if you have other working channels it shouldn't be too hard to follow the signal path until you find the fault.https://www.eevblog.com/2016/03/31/eevblog-864-siglent-sds2000x-series-oscilloscope-teardown/

author: Gaktyt
author_rank: Regular Contributor
timestamp: November 25, 2019, 09:45:34 am
content: Great, thank you for the link.Yes I have three working channels left :-) , so let me have a try.

author: tautech
author_rank: Super Contributor
timestamp: November 25, 2019, 09:59:38 am
content: You might also find this video Dave did on the front end of the later 4c X-E Siglent scope.https://www.eevblog.com/2019/07/10/eevblog-1228-do-digital-scopes-have-real-verniers/It may not give you much more than a better understanding the function of some of the IC's in the front end signal path.I'm sure if you write up your findings and methods used it can also help others too that blow a channel.Good luck with your fix.

author: Gaktyt
author_rank: Regular Contributor
timestamp: November 25, 2019, 02:26:43 pm
content: Thank you. Great idea, I will try to write something up.Would this be a sensible approach? I crack the scope open, power it up, put a signal on ch 4 (the blown one) and e.g. ch 2, then follow the signal on both channels with my spare scope, and when ch 4 does not match ch 2 I would have found the first defect component?

author: tautech
author_rank: Super Contributor
timestamp: November 25, 2019, 06:28:56 pm
content: Quote from: Gaktyt on November 25, 2019, 02:26:43 pmEssentially yes, until you get to the differential pairs where they won't be ground referenced so some thought and care need be used for where to place the probe reference lead and how to do this. You may need to use a differential probe if you have one.Hopefully you will find the issue before then and just connect the probe reference to one of the BNC shells.The probe compensation square wave output should be fine to use for the test signal.But before we get ahead of ourselves. the scope must come apart and yet parts need still be connected on the bench so it can be powered ON and be safe to work on. For extended ON time you need to provide cooling for some of the parts so you will need a bench fan.Depending how it all lays out on the bench and if you can see the display you might need a mirror too.There's every likelihood you can use one of the channels of the SDS2kX to trace the signal if you can see the display. A short custom link between the probe compensation output to the ch4 input could be handy to reduce the clutter on your bench.And pictures, everyone loves pictures !Take an analytical approach and work out where you need to probe, make drawings, study datasheets and mark test points with a fine Sharpie.Where you in 50 Ohm or 1M input mode when it was damaged ?

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 06, 2020, 07:02:55 pm
content: Hi tautechSorry for late reply, you know - holidays, other issues and general procrastination delayed me. But anyway, I cracked it open and there is not much to add to Dave's teardown, it's basically the same piece of equipment with some minor hardware revisions. Also I did not find any hand soldered diodes like in the teardown.Quote from: tautech on November 25, 2019, 06:28:56 pmI was in the 50 Ohm mode when it happened. I noted today that ch4 (the blown one) in 1M mode will only go up to 10V/DIV when turning the knob, whereas the other three channels go up to 100V/DIV. Also ch4 trace is not displayed at all on the screen.I have attached a picture of ch2/ch4 I was not able to identify the AUD 6683 chip. The KAQY214S is a ss-relay.I connected ch2 and ch4 to the reference signal. On ch4 most notably the signal is missing on AD8370 pin 16, AUD6683 pin 6 and the transistor I marked with a circle. But it is impossible for me to actually "follow" the signal, it's a 4 layer pcb and my hands are shaking from old age. I asked Siglent for a schematic, but oh noooo - it's a big secret.I don't know what to do but just replace the LMH6552 and AD8370. I can't identify the AUD 6683 and the four transistors in between, not even from the marking codes.

author: tautech
author_rank: Super Contributor
timestamp: January 06, 2020, 07:21:19 pm
content: The resistors are what I would check first and that's a bit of work to understand the coding/markings as they appear to be in A11 format.Have a look here:http://kiloohm.info/eia96-resistor/10X

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 06, 2020, 07:39:12 pm
content: Thanks, but why the resistors? (asking out of ignorance)When it happened I was measuring the output of a current transformer which yields only a few micro amps, the voltage however was a few hundred volts. I would have thought semiconductors would be the prime suspects? And I would need to de-solder the resistors to check them, unless there is a another novel way of doing it that I'm not aware of.

author: tautech
author_rank: Super Contributor
timestamp: January 06, 2020, 07:47:05 pm
content: Ah, OK then you are on the right path.In 50 Ohm input mode find the signal path and study the datasheets for each of the semiconductors in that path for their max input voltages and that may offer clues to the most fragile parts.I've never had a 2000X apart for repairs but for sure there will be someone here that has.Keep bumping this thread with your fault finding steps and discoveries until hopefully someone jumps in to help.

author: DaJMasta
author_rank: Super Contributor
timestamp: January 06, 2020, 11:39:45 pm
content: If there's actually no trace for the channel displayed at all (not just clipped to one rail or something), I'd actually start with checking the ADC. If you see a channel trace and it is just unresponsive, then it's likely something in the front end (which is much more typical of overvoltage damage). Now there's a chance that if one of the chips in the frontend doesn't respond to commands it just disables the trace - in which case looking at them would be a reasonable choice - but if you're really not seeing anything, it may be a digital domain issue, which would mean pretty extensive damage. If it were just blown passives/dumb programmable gain amps/relays/etc., I would still expect to see some kind of trace displayed, it just wouldn't show any signal, or it would show an entirely wrong signal.

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 07, 2020, 11:18:47 am
content: Hi DaJMasta!Quote from: DaJMasta on January 06, 2020, 11:39:45 pmThere is NO trace whatsoever, nada, nista, niente, ничто, nichts. And the only way I can think of to check the ADC would be to swap the inputs of ch3 and ch4 (which goes to the same ADC), but it's a BGA component on a minimum 4 layer pcb, so chances for success are slim.Quote from: DaJMasta on January 06, 2020, 11:39:45 pmI guess that is the chance I'm hoping for. The most tangible and workable fact so far is:On INLO (low input of diff amp, pin 16) on the AD8370 there is no square wave signal, only something that resembles a floating pin. Which obviously means there is no square wave on the output of the AD8370.Quote from: DaJMasta on January 06, 2020, 11:39:45 pmOr it could be the worst of worst case scenarios, both digital & analog problems.

author: DaJMasta
author_rank: Super Contributor
timestamp: January 07, 2020, 03:52:15 pm
content: Yes.... if an overpower event happened and you managed to cook your ADC, the whole input section would likely be charcoal...Hoping for the PGA or something in the path just not returning usable info to the monitoring systems!

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 08, 2020, 02:47:01 pm
content: After some more measurement I decided to try replace the following three components, but I need some help to translate the smd marking codes into part numbers so that I can order them.K52G- SOT-23 I believe it's a transistor of some sort NPN/FETAUE 6683- SOIC-8 I believe it's a op-ampT4- I believe it's a diodeCan you please assist?

author: goaty
author_rank: Regular Contributor
timestamp: January 08, 2020, 03:04:13 pm
content: K52G could be BAV199T4 could be 1N4148

author: thinkfat
author_rank: Unknown
timestamp: January 08, 2020, 03:19:02 pm
content: AUE (6683) might be a TI OPA727 in VSSOP-8 package.

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 08, 2020, 06:15:53 pm
content: Hi goatyQuote from: goaty on January 08, 2020, 03:04:13 pmThank you for your suggestions, the BAV199 was also suggested to me from others, so I will order that. And the T4 yes I was also thinking some small signal diode like the 1n4148.

author: Gaktyt
author_rank: Regular Contributor
timestamp: January 08, 2020, 06:18:46 pm
content: Hi thinkfatQuote from: thinkfat on January 08, 2020, 03:19:02 pmYes I think so too, but still a bit suspicious because the TI datasheet says smd marking is only "AUE" no mentioning of "6682".

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2020, 06:44:19 pm
content: Quote from: Gaktyt on January 08, 2020, 06:18:46 pm6682 will be a production/date code.Datasheets normally show what it means.

author: DaJMasta
author_rank: Super Contributor
timestamp: January 09, 2020, 01:20:09 am
content: Quote from: Gaktyt on January 08, 2020, 06:18:46 pmThere is some chance that the other marking is on the bottom side - if you end up pulling it to replace it, it's worth a check.

author: marq12345
author_rank: Newbie
timestamp: January 04, 2024, 06:03:44 pm
content: Sorry to revive an old thread, but I recently damaged channel 2 on my 1104X-E and a google search brought me to this thread while I was trying to identify components. The trace for this channel was off-screen no matter what I did with gain, vertical offset, or AC coupling. The front-end also has a SOT-23 package marked K52G, which was shorted. Turns out it is actually the input JFET to the discrete amplifier, 2SK508G, but I couldn't easily find it from Digikey etc... so I ordered it from LCSC (Which I think the is parent company of JLCPCB):https://www.lcsc.com/product-detail/Bipolar-Transistors-BJT_UTC-Unisonic-Tech-2SK508G-K52-AE3-R_C258268.htmlAfter replacing it, the scope seems to work normally again, so this JFET is at least a good enough match. Also, while it was still broken, I attempted a self-cal (which didn't help), and after replacing the JFET, I had to self-cal again for the trace to appear back where it should. Surprisingly, in my case, the two protection steering diodes to 5V and 0V at the input of the JFET are still ok. Hopefully this helps someone in the future.

author: FringIdeas
author_rank: Newbie
timestamp: September 24, 2024, 08:58:16 am
content: @marq12345, and everyone else with the pics, links, etc, thank you!I had the same scope, 1104X-E, with the same problem, the trace would not stay on the screen. I found nothing while internet searching the first few times. Then accidentally found this thread. I went and ordered a few 2SK508G-K52-AE3-R from the link. Took about a month to get to me, but I got them. I opened the scope and the K52G did seem to check out bad. So I replaced it with the new part, fired up the scope, did a self calibration, and I got my trace back!! So happy.. so happy..Thank you for sharing the information!

author: Deso
author_rank: Contributor
timestamp: November 29, 2024, 10:40:29 pm
content: Quote from: FringIdeas on September 24, 2024, 08:58:16 amVery interesting. Can you share more details?I have such a problem with my sds1104x-e, but I have no idea how this happens to me (I'm not a novice and this is the first scope in my hands that broke).One day I was measuring some things and a few days later I came back to update to the latest firmware - V6.1.37R17. After the update I get the very same problem - no waveform on the screen at all. All channels act like that. I have been in communication with the seller and Siglent support, although it is under warranty, it seems that this issue will not be covered. Siglent support provided me with a recovery firmware that downgraded the firmware and I started seeing something on the screen. They don't seem completely dead, as they can measure the calibration signal with erroneous measurements on the screen, but they can't detect lower signals. I use only 2 channels almost all the time, but last time I ended up using only channel 1. I can't explain how all 4 channels stop working at once.If anyone has any idea what could be causing or fixing this, it would be helpful to me. Thanks!

author: tautech
author_rank: Super Contributor
timestamp: November 30, 2024, 12:16:20 am
content: Quote from: Deso on November 29, 2024, 10:40:29 pmFrom what previous version ?In the install instruction they recommend immediate running of the Self Cal after the FW update.Did you do this at any time ?Even after running the recovery package ?Make contact via PM with your email address and we'll work through getting you all fixed up.

author: Deso
author_rank: Contributor
timestamp: November 30, 2024, 08:14:54 am
content: Quote from: tautech on November 30, 2024, 12:16:20 amThank you Tautech.It was with SW 6.1.37R10 and I upgraded to 6.1.37R17. Of course, I performed a calibration and after not seeing any waveforms, I started "default", "security erase" and all that kind of stuff. I reverted back to SW 6.1.37R10 and followed the same steps, but there were no waveforms at all. Finally, I flashed the recovery firmware and performed a calibration. It started showing waves that were wrong.Quote from: tautech on November 30, 2024, 12:16:20 amDone.

author: tautech
author_rank: Super Contributor
timestamp: November 30, 2024, 08:31:53 am
content: Quote from: Deso on November 30, 2024, 08:14:54 amVia PM:Run recovery package.Then install OS update.....which installs like a recovery package....at boot.https://int.siglent.com/upload_file/zip/firmware/Oscilloscope/SDS1xx4X-E_EN.zipThen install latest firmware:https://int.siglent.com/upload_file/zip/firmware/Oscilloscope/SDS1xx4X-E_V6.1.37R17_EN.zipReport the outcome.Edit:Run Self Cal.

author: Deso
author_rank: Contributor
timestamp: November 30, 2024, 09:43:23 am
content: Done. There are no changes regarding the reported issue. It still doesn't measure correctly.

author: tautech
author_rank: Super Contributor
timestamp: November 30, 2024, 10:08:27 am
content: Quote from: Deso on November 30, 2024, 09:43:23 amYup, based on the pics you set me, time to claim warranty.

author: Deso
author_rank: Contributor
timestamp: November 30, 2024, 10:20:22 am
content: Thank you for looking into the issue Tautech.I'm trying. Once I have news I will update the topic.