Issue with 1 channel of a brand new DS1054Z - Page 1
Forum section: electronics / repair

author: awinslow
author_rank: Newbie
timestamp: December 06, 2017, 05:31:06 pm
content: Last week I finally broke down and bought my 1st scope to step up my electronics hobbyist game. I got a new Rigol DS1054Z from tequipment.net during their big $50 off and all the software options sale. I just recieved it and during initial messing around with it to learn to the controls I noticed something strange with channel 4, when I had it on a 5v DC source it was claiming the voltage was around 9.5v while the other 3 channels reported the correct value. This had me confused so i attached all 4 channels to the square wave test point in the front of the scope and looked at the wave form (screen shot is attached). Channels 1-3 were all bang on but channel 4 was very distorted and was showing as a higher voltage. I tried changing around the probes themselves but it made no difference. Next I figured I had somehow messed up some setting somewhere when I was messing around in the menus so I did a full factory reset of the scope and that didn't help. Finally I looked up the procedure to do an Auto Calibration which did not help. It gave no errors or anything just ran then said to restart the scope. The final strange thing I noticed is it seems to work fine for about 10 seconds after a cold boot where all 4 waveforms are identical from the test point but then channel 4's starts slowly moving up to the position shown about 20 seconds after boot and stays there.Is there something I am missing or something I can try to do other than what I have done to try fix it or is this just something I will have to get replaced?Thanks for any help!

author: StillTrying
author_rank: Super Contributor
timestamp: December 06, 2017, 06:08:03 pm
content: It looks like you haven't calibratedthe probesusing the 1kHz to me.

author: imidis
author_rank: Frequent Contributor
timestamp: December 06, 2017, 06:11:37 pm
content: I assume you followed the steps start up > storage defult > hook up probes in 10x (on the probe switch) and then hit auto and adjust with screw if any are off (connected to the compensation signal of course) pg34 of the manual

author: awinslow
author_rank: Newbie
timestamp: December 07, 2017, 12:26:22 am
content: Thanks for the suggestion. I just gave it a try and the procedure made the probes for channels 1-3 perfectly square but wasn't able to get even close to correcting channel 4. It did have an effect but it was minimal. Ive attached quickprint4 and quickprint5 to show both extremes that I was able to get by adjusting adjusting the probe compensation screw. quickprint6 shows my now compensated channel 3 with the still vastly out channel 4 being distorted and claiming the compensation signal is over 5v instead of the 3v it actually is. I looked through the user manual and didn't see any way to do a much more coarse compensation to try to get the channel close enough that the probe screw would be able to correct it. Anyone happen to have any other suggestions?

author: StillTrying
author_rank: Super Contributor
timestamp: December 07, 2017, 01:08:29 am
content: You could try another self-calibration when it's warmed up with all 4 probes off, but it's certainly looking like CH4 is faulty.

author: metrologist
author_rank: Super Contributor
timestamp: December 07, 2017, 01:28:48 am
content: Did you try other probes on that channel, to eliminate a defective probe?

author: imidis
author_rank: Frequent Contributor
timestamp: December 07, 2017, 01:39:26 am
content: I agree, I think channel 4 is faulty.

author: Samogon
author_rank: Frequent Contributor
timestamp: December 08, 2017, 04:22:07 am
content: Time to get RMA from Tequipment

author: bd139
author_rank: Super Contributor
timestamp: December 08, 2017, 07:30:03 am
content: Quote from: metrologist on December 07, 2017, 01:28:48 amThis.Could be bad compensation network in the probe.

author: drussell
author_rank: Super Contributor
timestamp: December 08, 2017, 01:55:13 pm
content: Quote from: metrologist on December 07, 2017, 01:28:48 amQuote from: bd139 on December 08, 2017, 07:30:03 amApparentlyawinslowalready tried that in the first place. See the original post:Quote from: awinslow on December 06, 2017, 05:31:06 pm

author: bd139
author_rank: Super Contributor
timestamp: December 08, 2017, 02:56:30 pm
content: Ok I didn't see that. I will don the "dumbass hat"

author: alsetalokin4017
author_rank: Super Contributor
timestamp: December 08, 2017, 03:02:41 pm
content: Quote from: imidis on December 07, 2017, 01:39:26 amYep, sounds like that to me too. Contact Tequipment right away, and be sure they agree to pay shipping both ways for your replacement scope.

author: Terry01
author_rank: Frequent Contributor
timestamp: December 08, 2017, 05:07:17 pm
content: To me that looks like Ch4 is doing Math between Ch 1,2 and or Ch 3 as a + between a square wave and a triangle wave form. I am not familiar with the Rigol scope though so don't know how to set it. Maybe someone more familiar can tell you where the setting is.Look in the Math Menu and see if you can see it. Somewhere it looks like Ch4 is + a square and triangle wave form together from 2 channels.Good luck.

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: December 08, 2017, 05:33:42 pm
content: Quote from: Terry01 on December 08, 2017, 05:07:17 pmNo, Math function is displayed as purple on the DS1000Z scopes.

author: awinslow
author_rank: Newbie
timestamp: December 08, 2017, 06:49:08 pm
content: I just ran the scope for about an hour to make sure it was warmed up fully then ran the auto calibration again, no change. As for the probes at this point I think I have tried every probe on every channel trying to debug this and all 4 probes work in channels 1-3 and all 4 show the distorted waveform in channel 4. For the math function suggestion that had been one of my 1st thoughts when i saw the issue, that maybe I had changed some software setting or mode without realizing it, so I had done a full factory reset on the scope to no avail. Ok, I will reach out to tequipment.net about getting the scope RMAed. Thank you for the suggestions everyone!