Owon PDS 5022S

Eeuuwww. Pure guess .... One of the voltages on the display tube itself has gone off. Right orff. Could be that a cap has broken down. But in a very worst case, a weld inside the display tube has opened up.

Don't be afraid to open it up, just be carefull.

Could be something simple. I had a TDS210 that was shipped with a reversed and burst electrolytic. Worked fine for a while before requiring a simple fix. Display showed first symptoms.

The bloom around the LCD display looks physical, to me.

As a battery-powered device, it'll have it's uses.

I have a few Owon SDS8202s that are eating their batteries regularly. I've introduced balancing, internally, but the charging circuit possibly overvolts the battery chemistry. Simple is good, but ignoring the float upper limit is just stupid.

RL

Ummm... it's not a CRT. It's a color LCD 640x480 panel.

I haven't torn the DSO apart yet. The display is not packaged to make disassembly or inspection easy. I've seen literally hundreds of computer LCD panels but never one that looks like the photo.

It's not a CRT.

Thanks for trying.

I'm fearless and moderately careful. My problem is that I'm in the process of purging all the old junk from my house. When I retired and closed the office, I had to drag everything from the office to the house. The house has been a mess since Sept 2020. I have quite a bit of equipment that I know can be fixed if I had the time and bench space. For this DSO, the problem is both lack of time and lack of bench space. I can't just tear it apart and leave it. The reason I asked for clues is to save time monopolizing the workbench and troubleshooting the problem. In this case, I've seen literally hundreds of failed LCD computers displays, but none have ever looked like the photograph.

The DSO is old enough that a bad electrolytic is a likely problem. I couldn't find any information that would help establish the age. So, I measure a few voltages. If that fails, I find where my ESR tester is hiding and check every electrolytic.

There's no evidence of a crack in the display.

It has an AC charger and power supply built in. The battery pack is proprietary. I plan to use the AC PS for testing and to build a suitable battery pack when it's fixed.

Incidentally, I used it for about a year before it suddenly quit. It's only 20MHz bandwidth, but that was good enough for audio.

That's a much later 200MHz DSO:

Thanks for trying. I'll try to remember to post something when it's fixed, sold as-is or recycled.

Yeah. The sunlight shone just after I clicked "send" Serves me right for " living in the past" -)

Video of a Digimess DS25 DSO, which is similar to my Owon PDS5022s:

More videos: This PDS5022S video is 14 year old with upgraded firmware:

More of the same:

Some photos of the internals:

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:

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.

If the DSO doesn't magically fix itself in the next few days, it's going to the local recycler.

The pattern of 'bloom' looks like poisoning from an adhesive layer.

I crack mine open, replace the cells and add a balance w/test points, then re-seal. I haven't 'adjusted' the EOC charge voltage yet. Probably before the refurbed battery sets (always bought 2 with each scope) are fried. Or a battery disconnect switch.

I use the mains 'off' switch when not in use and plugged in. Never leave it quiescent and plugged in - that green light is a fool's reassurance.

SDS was successor of PDS.

Battery management in the SDS is so rudimentary and ignorant of internal ( ~third party) battery characteristics, that it can't always manage to under-voltage reliably. One of mine corrupted it's own firmware recycling on/off on a low battery in the first few months and went back under warranty.

Software battery gauge is a joke.

Not all LiIon chemistries have the same EOC voltage - I think the chemistry was changed after they shot the design engineer. (Ship it!)

RL

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

I give up. I poked around for about 3 hours and determined that everything seemed to be working except the LCD panel. Since a replacement panel was not easily available and a used planel was likely to have the same problem, I decided to recycle the DSO. I will probably offer it as burnt offerings to the proper diety on the barbeque or just pass it to the local recycler. Or, I might use it for target practice.

My thanks to those who tried to help me fix it.

• User FidoNet address: 1:396/45 Hello All.

l> l>

l> 1.jpg>

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

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

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

Regrettably, the lack of service data prevades the system. I do professional audio repair work... Been doing it for 56 years now. In the past, many if not most manufacturers provided full-blown schematics/service manuals.That number has dwindled down a LOT. Some of the so-called schematics re just partial with blocks that show nothing, just lines connected to them. Useless. Same goes for a few industrial units I work on. A complete non sequitur. You pay thousands for a unit -- you expect it to be repairable. <frown>

Then there are the units that may be servicable, but one finds many of the components slathered with silicone rubber se alant... Again, unservicable. Frustrating, not only to me but to the client.

Best regards, Marc Lewis, CET Service Manager QTI Service Centre Huntsville, AL USA