OWON SDS7102 - Waveform display Problem - Page 1
Forum section: electronics / testgear

author: candrian
author_rank: Regular Contributor
timestamp: December 03, 2012, 10:13:13 pm
content: Hello,I own an OWON SDS7102 Oscilloscope. Today i had an issue with the waveform display.To make sure that it isn't any configuration fault i restored factory default settings and i connected channel's 1 probe to the oscilloscope's internal waveform generator. When i have volts/div at 1 Volt/div or less and probe at 1X the waveform is appeared as supposed to. When i change the Volts/Div to more than 1 Volt the inside relay click is heard and the waveform is disappeared.Has anybody any idea what is going wrong?Here is a video demonstration

author: AndrejaKo
author_rank: Frequent Contributor
timestamp: December 04, 2012, 12:58:34 am
content: Well I can't see anything on that video because it's so blurry. Do you have a better camera available or at least a very bright light so the screen of the scope doesn't affect the video recording?Since this is related to the relay switching, I'd say that it could be signal path damage. Does this happen on the channel number two as well? Is the probe set in software to 1X? From little I can see on the screen, I'd say that in software, the probe is still set to 10X. If that's the case, you're probably overloading the input. Remember, when the probe is set to 10X in software and you're using 1X probe, maximum voltage that can be displayed is just 1 V when you're in 1 V/div mode! Basically everything is divided by 10. You have one range which is from 2 mV/div to 100 mV/div (maximum input voltage ±1 V), one which is from 200 mV/div to 1V/div (maximum input voltage ±10 V) and one which is from 2 V/div to 10 V/div (maximum input voltage ±100V). The waveform generator voltage is +5 V, which is above the input level of the lowest range. Also when you have voltage measurement turned on, you'll see a question mark after voltage value if you have exceeded the input voltage for the range.So here's what you can try: First turn up the voltage range up until you get into 20 V range. You should hear a click. Right now, the image should be back. If that's the case, set the probe in channel 1 software to 1X and you'll see that the shown voltage dropped to 2V and everything should look fine.What did you do with the scope when this problem happened for the first time? Tell us exact voltage ranges and probe settings. To me this looks like the voltage range on the scope burned, but I could be wrong.Unfortunately, I don't have any smart ideas how to fix this.

author: aghp
author_rank: Regular Contributor
timestamp: December 04, 2012, 05:31:43 am
content: Quote from: AndrejaKo on December 04, 2012, 12:58:34 amIf oscilloscope is fault in normal use without any misuse. (burned input)Take contact to your seller. Oscilloscope have 3 year warranty.If your seller can not help you then contact to Owon for arrange warranty repair.But first it need know if there is real fail.Your video do not show anything real. For what is this "video"?First do factory default.1. Run selfcal as described in manual: How it go?(do not connect anything to oscilloscope inputs and do not even touch them or do not go near inputs with anything as long as selfcal is working. (inputs are sensitive and selfcal signals go through inputs inside scope)2. Do not connect anything. Adjust both traces example to near vertical centerline.Turn both voltage adjustnments all steps and look both traces are visible near centerline.If there is some voltage setting CH1 or CH2 where trace disappears totally there is propable fail. Also in every step touch with finger to input (example some short wire in hand) and look if you see "something". If some step(s) just "dead" and others react. Suspected fail.Of courrse best is if you have real trusted signal generator and can do full test with it, do it with it.

author: candrian
author_rank: Regular Contributor
timestamp: December 04, 2012, 02:48:22 pm
content: Thank you for you replies.When i came across this issue i was trying to measure the voltage across a Mosfets which implements a voltage booster (typically max voltage 70V DC). I measured the voltage with a multimeter and i saw that it was no more than 15Volts. So i think that it isn't possible for the oscillator to have burned. Note. I don't remember the oscilloscopes configuration (Volt/Div etc.)The latest things i tried:1. Update firmware to the latest version 2.8.12. Restore default settings3. Do self calibration (after the firmware update this function is executed a lot faster)But with no result.Here is a video i captured when i tried the above. Isn't supposed to display two DC lines after the self calibration and default settings, indicating that there is no signal input? The two indicating DC lines for no signal input it looks like that appear at the bottom of the display with no change when i try to move their position upper adjusting the Vertical Position button.

author: candrian
author_rank: Regular Contributor
timestamp: December 04, 2012, 05:20:03 pm
content: It looks like an unadjustable offset has been added moving the waveform down so that you can't see it on the display. I have tried adjusting the vertical position to full top value with no result.With the following configuration: Probe X1, actual Probe switch to X1 as well as Volts/Div less than 200mV (the limit of first relay click) and the probe connected on the Probe Comp i can see a part of the waveform (i believe it's the top side of the waveform). If i move the Volts/Div to 200mV or more the waveform disappears and a straight line can be observed at the bottom of the display (like the normal DC line when no signal input but now it's at the bottom of the display and you can't move it with vertical position button).Instead of changing Volts/Div if the configuration is Probe X1, actual Probe switch X1 and Volts/Div is 100mV and i change Probe's switch from X1 to X10 the waveform also disappears (without any relay click) and a straight line at the bottom of the screen appears again.

author: candrian
author_rank: Regular Contributor
timestamp: December 06, 2012, 04:17:08 pm
content: Here is another video.Configuration:Cable Probe X1, Software Probe configured to X1, Volts/Div 500mV, Voltage supplied about 25Volt DC

author: aghp
author_rank: Regular Contributor
timestamp: December 06, 2012, 06:23:03 pm
content: It clearly looks like your oscilloscope have hardware failure on the mainboard.This forum do not repair it so it is waste of time if thinking here in many places what is this and whjat is propably wrong etc.Right road is now:Please contact your seller. if they can help you for arrage warranty repair then let them do it.If they can not, then go to:http://www.owon.com.hk/aboutus-en.asp?id=38Right side of this side you find "Sales" and "Technical support"Click Technical support and talk live with Owon or leave message if they are offline. (China time is +8h GMT)If you leave offline message, for saving time:Explain shortly and clear your problem.Tell your oscilloscope serial number, and version number what scope show. Who is seller and day of purchase and your location.Ask they arrange repair service as fast as possible.You can take picture using USB. (Owon support may ask some picture and follow what they ask... but if they just ask in this case just some image...then example..First default. Connect all out from all inputs. (inputs NEED be just empty, no probes or any other things connected to input BNC'sDo selfcal and during selfcal do not touch inputs.If selfcal generate some failure note then write it down and tell it.After selfcal, connect direct wire (or probes if probe is sure ok) from probe comp output to both channels input center pin.Push autosetup.Take picture to USB or directly to PC.It is they headace analyze what is problem. You need only answer if they make some special questions or ask you do some test for analyze and classify problem.Remember that they have lot of load in support and answers may have some delay becouse still there is situation that most ot too many resellers do nothing for after sales customer care - pity.If all help fails, you can also contact me (PM) if I can try arrange some help for you (just now I vcan not due to lack of time) but honestly I can not promise - my time for free extra work is very limited, specially now becouse I have just ago arrived back from China and here is now queued tasks waiting.

author: jonmarx
author_rank: Contributor
timestamp: July 21, 2013, 02:38:06 pm
content: Hi Candrian,Did you manage to contact Owon and get your oscilloscope repaired under warranty?I'm thinking of buying a SDS7102V so it would be interesting to know how good (or bad!) Owon's technical support is.Regards,Jon

author: lemon
author_rank: Frequent Contributor
timestamp: July 22, 2013, 09:06:32 am
content: I hope so to have an answer from Candrian member, but this thread is 7 months old.The Owon technical support is good until now with exception their politics about ground noise issue at some s/n.

author: candrian
author_rank: Regular Contributor
timestamp: August 04, 2013, 09:03:00 pm
content: Yes, i came in contact with Owon's support center and after they found out what is the reason of the problem they send me a replacement main board (with no charge - warranty ). I replaced the main board on my own, as an ECE and everything was working fine. (replacement instructions was sent via email).As they specified, after replacing the main-board on my own the scope's warranty wasn't affected.

author: leafi
author_rank: Regular Contributor
timestamp: August 05, 2013, 01:59:12 am
content: I have a sort of stupid question. You have the scope ground apparently hooked up to the gnd on the power supply but the negative lead of the power supply does not appear to be grounded. The output power supplies that have a seperate ground are normally isolated and need gnd to be hooked up to - to have their voltage referenced to ground rather than the negative lead. Can you verify this? Maybe it is something simple.