OWON VDS1022 CD Eye pattern - Page 1
Forum section: electronics / repair

author: abhi1981
author_rank: Regular Contributor
timestamp: November 26, 2022, 09:03:28 am
content: Hello,Just got an OWON VDS 1022 from Amazon for around $87 (INR 7125). This is my first oscilloscope.An analog scope would have been better but couldn't find one. The ones available were either expensive or badly abused.Connected it to my Yamaha CDC 635 for an eye pattern and the result is shown in the below image. It sometimes starts skipping CDs.I think the refresh rate at infinite persistence is quite slow. What do you think??I have also attached a link to the video showing the eye pattern at different persistence settings.https://youtu.be/DVgZDktMNmkI have connected the probes via jumper leads, as the test points were under the tray and impossible to reach. Otherwise, the board will have to be taken out.

author: Manolo Mos
author_rank: Contributor
timestamp: November 26, 2022, 05:49:36 pm
content: Hi. The oscilloscope looks to perform well. The first image is correct to see the RF signal. The RF signal looks to be noisy, maybe it needs to correct Focus Offset adjust. But I insist, oscilloscope looks to be OK, RF is noisy, laser pickup is giving a noisy signal. And yes, sometimes is not easy to get RF signall with a probe. Attenuation by 10 is recommendable too for to see RF signal in CD laser pickups.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: November 26, 2022, 06:57:03 pm
content: An analogue scope would not have given you that amount of detail.Good choice.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 26, 2022, 07:52:36 pm
content: Quote from: abhi1981 on November 26, 2022, 09:03:28 amOWON HDS242 is very fast update rate. $100+ (add only few dollars), 40MHz, 250MSa/s, portable and no need PC, DMM mode..

author: Gyro
author_rank: Super Contributor
timestamp: November 26, 2022, 10:02:27 pm
content: Quote from: Mechatrommer on November 26, 2022, 07:52:36 pmWow, a whole 3.5" 320x240 display, awesome!

author: Audiorepair
author_rank: Frequent Contributor
timestamp: November 26, 2022, 10:15:23 pm
content: Despite the noise, its not hard even for a human to tell the difference between a "1" or a "0" from this data.

author: abhi1981
author_rank: Regular Contributor
timestamp: November 27, 2022, 09:15:51 am
content: Thanks everyone for your valuable comments.Maybe the noise is caused by the jumper wires. I'll try using a shielded wire.The CD tray is also very sluggish. Changing the belt didn't help. Greasing the gears and rails also didn't help.The motor controller IC TA7291P also becomes quite hot.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 27, 2022, 09:45:39 am
content: Quote from: Gyro on November 26, 2022, 10:02:27 pmfor a long time i was eyeing portable scopemeter things like hantek 2000 serieshttps://www.eevblog.com/forum/testgear/hantek-2c422c722d422d72/?topicscreenand others tablet and china cheap scopes, but their GUI look very basic, some has one channel only and slow update rate is the common one etc. when i saw Hantek HDS 200 serieshttps://www.eevblog.com/forum/testgear/owon-hds-200-handheld-oscilloscope-w-builtin-dmmawg/msg3451228/#msg3451228i thought this is it, the update rate is one big step ahead, so i punched the button and get 500MSa/s HDS2102S for a bit more than $200 (since i think its time to get one such portable scopemeter unit), and then later came 1GSa/s HDS2202S for a bit more. this scopemeter reminds me of my DS1052E except with basic edge triggering method (which is standard among all portable scopemeter i've seen anyway)... imho people should search in eevblog first before risking buying relics or the wrong item in the market, unless they have very specific reason. but i think eevblog has expanded with many threads everyday that even seasoned members can miss lots of recent news, ymmv.

author: thinkfat
author_rank: Unknown
timestamp: November 27, 2022, 01:44:51 pm
content: What you have on the screen is not an eye diagram. For that you need to trigger on the regenerated sample clock.What you're seeing there is just a data signal. It's hard to say anything about its quality like this.

author: abhi1981
author_rank: Regular Contributor
timestamp: December 05, 2022, 08:31:37 am
content: Returned the scope as it was hanging up and the lagging was quite annoying.Back to square oneNow, I'll have to look out for an analog scope.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 05, 2022, 08:40:58 am
content: Quote from: abhi1981 on December 05, 2022, 08:31:37 amgood luck!