Author of the article.
https://www.eevblog.com/forum/testgear/review-of-owon-sds7102/?action=dlattach;attach=56620
Snubbers Using Standard Recovery Diodes.
Cheap and slow is not bad.
Designing R2CD Snubbers Using Standard Recovery Diodes
http://www.intusoft.com/lit/Designing%20R2CD%20Snubbers%20Using%20Standard%20Recovery%20Diodes.pdf
Author of the article.
https://www.eevblog.com/forum/testgear/review-of-owon-sds7102/?action=dlattach;attach=56620
Snubbers Using Standard Recovery Diodes.
Cheap and slow is not bad.
Designing R2CD Snubbers Using Standard Recovery Diodes
http://www.intusoft.com/lit/Designing%20R2CD%20Snubbers%20Using%20Standard%20Recovery%20Diodes.pdf
Just TomC has concentrated to psu board, I am thinking to focus to the adapter board.
I don't have the time to make a schematic for all this board but I'll search some dc-dc convertors, difference btw Ver 3.0 and 3.2 and so on.
At the first I am looking the AOZ1094AI dc-dc convertor that produce the 5.5V.
What Owon makes at the the two versions? Look at the attachment photo (left is 3.2, right is 3.0 version).
At the version 3.2 corrects the badly cutting of gnd that previous was made (point 1). Removed the smd capacitor C36 (point 2), adding a second inductor 5.6uH with some smd decoupling capacitors (point 3). The changes was few and very easy to make but is that according to AOZ1094 datasheet?
The next schematic is from datasheet of convertor, a general proposal for 3.3V output. For 5V output the factory suggests L1=5.6uH, Rc=31.6KOhms, Cc=1nF.
For what reason the Owon uses two 5.6uH inductors? For what reason has made mods by hand on version 3.0 with adding a 10uH inductor? Of course was the eliminate the noise but what are they compute.... ?
If you looking more carefully at the schematics, missing some components!
Where the C5=1000pF capacitor that joined the AGND and Enable?
Where is the parallel to diode Rs and Cs components?
At the output the factory suggest two 22uF electrolytic capacitor or some combination : "For lower output ripple voltage across the entire operating temperature range, X5R or X7R dielectric type of ceramic, or other low ESR tantalum or aluminum electrolytic capacitors are recommended to be used as output capacitors."
Have all these in my mind I'll make a check again and I am going to follow the datasheet...
Please, if someone looks the values of smd resistor R18, R19, R20 and R21 on Version 3.2
What kind capacitors are they because you have bridged all of them with the first two parallel pins.
Hi to everyone. My new results. - From the network 18-22 Vpp, battery 12-18 Vpp. Reduced noise from the screen. Added capacitors on the conclusions of the LCD screen ( 0.08 nF which are used in many LCD screens). After this enhancement, there are some distortions on the monitor output.
All power DC-DC original. Added filter and transfer to another place.
This is ver 3.3
Here is a link to the uncompressed version of the Version 3.2 Adapter and New PSU photos. This link has an expiration date of November 2013. Until then the photos will be available for viewing or download.
http://sdrv.ms/1cOVr1M
This is ver 3.3Flash2light,
The component side looks identical to version 3.2. Is there an SMD capacitor underneath C34? That's the only thing Owon had me add to my 3.2 adapter board when I purchased a new PSU board.
I'm also curios about the GND noise level on your scope, on page 92 post 1373 you can see the GND noise level on my scope after I replaced the PSU board and modified the adapter board with an SMD capacitor under C34. It would be very nice if you posted some captures of the GND noise level on your scope for comparison.
This shows the noise.
original condition. Not modified.
Ver. sds7102 1319 331
where is the ferrite? I have a ferrite flat cable.
I have not tried its effect.
Carrington, thanks for the link with information about capacitor type.
Can you tell us how much was the cost of the two boards and how you paid them?
Of course we'll waiting what versions you'll get up and some photos of course.
What are you said my friend? 45$ only?
I have bought the Owon for the Aidetek USA (but is was coming directly from China to my country). I think must to be a contact with them about this. Many many thanks for this information.
Have you tracking information for the arrived day?
The big difference is at TFT Backlight LED power supply. There is an other IC (really can someone find what is S126k) probably a TPS61161A (I don't see clearly) with different power supply.