Re: Owon PDS 5022S

On Thu, 15 Aug 2024 20:34:51 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Wed, 14 Aug 2024 14:26:48 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
>

A few years ago, my Owon PDS 5022S oscilloscope failed with a strange
looking display.  See photo at:
<https://photos.app.goo.gl/rYGeaGygSMXHtMCb8>
From what is visible on the display, everything seems to be working
except for the strange display.  Whatever is wrong is probably in
either the color LCD display or the circuitry that drives the display.
Does anyone have a clue what might have failed?  Mostly, I'm trying to
save time fixing it.  (I haven't torn it apart yet).
>
User manual (no schematic or block diagram):
<https://www.saelig.com/downloads/pds5022s.pdf>
Specs:
<https://www.batronix.com/shop/oscilloscopes/digital-oscilloscope-pds5022s.html>

>
Video of a Digimess DS25 DSO, which is similar to my Owon PDS5022s:
<https://www.youtube.com/watch?v=yfjh0KDEaTY>
The plastic case, front panel, and oscilloscope section are identical.
However, the LCD panel, power supply and backlighting inverter are
very different. 
>
More videos:
This PDS5022S video is 14 year old with upgraded firmware:
<https://www.youtube.com/watch?v=JQtvW1wpl6w>
>
More of the same:
<https://www.youtube.com/shorts/6OCnuXpM2mY>   (same problem as mine)
<https://www.youtube.com/watch?v=M0galCMhm7U>
<https://www.youtube.com/watch?v=nydo6xsLY7g>
<https://www.youtube.com/watch?v=hzZpE9yrMKA>
<https://www.youtube.com/watch?v=UInlOkFDf24>  (shows defective LCD)
<https://www.youtube.com/watch?v=X1OTPt7_1Z8>
<https://www.youtube.com/watch?v=1sUGiwaEjq8>  (shows defective LCD)
<https://www.youtube.com/watch?v=xHaapgrXxYI>
<https://www.youtube.com/watch?v=escwIX0vY64>  (looks similar to mine)
<https://www.youtube.com/watch?v=EQXzP6sazaA>
<https://www.youtube.com/watch?v=MNzaAPetnVw>
<https://www.youtube.com/watch?v=K3mITKGuAW4>
<https://www.youtube.com/watch?v=bjRQP8mDCV0>
>
Some photos of the internals:
<https://photos.app.goo.gl/ZgCRUB4SChDYRrRy6>
When I removed the cover, I was immediately hit with the distinctive
smell of burned resistor.  I tried to find the source with my nose,
but failed.  When I "fire" it up again, I'll do some more fault
"sniffing".
>
Visual inspection didn't find anything that looked like a problem.  I
tested all the electrolytics with an ESR tester.  I did another visual
inspection with a microscope:
<https://www.learnbydestroying.com/jeffl/pics/microscopes/Olympus%20SZ30/SZ30-01.jpg>
No problems found. 
>
I think it's the LCD panel.  There are replacement LCD's on Ali
Express and eBay for about $140.  However, the scope is selling on
eBay for about the same price.
<https://www.ebay.com/sch/i.html?_nkw=owon+pds5022s>
This one has the same problem as mine:
<https://www.ebay.com/itm/285811299516>
>
If the DSO doesn't magically fix itself in the next few days, it's
going to the local recycler.

They're doing no-one any favors by making service info and replacement
parts unavailable.

Even so, stocking lcd displays for ten year gone product is
probably asking a bit much. Imagine if they did?

There's nothing particularly special about their circuitry, that
needs protection. It's all in the firmware. What needs protection
is the end user.

RL