RPL1116 (MSO1000Z) and PLA2216 (MSO5000) Active Logic Probe teardown

[whowe]

I also have made a copy of your Rev2.
I planned to use JLC, but the verification girl insisted it's a "5-board" one and the price was almost 100 USD. I failed to correct her that it was "2 designs only" board. Finally I had to change to another vendor who does not understand impedance part.
Anyway, the board is being shipped to me now. And I also purchased 2 LMH7324 directly from TI (FedEx from Texas) which is expensive but should be genuine.

Hoping for the best result.

Got them. Although the PCB manufacturing is really not good.

[ebclr]

Do you have any spare set of boards to sell/share

[whowe]

I would like to share them, but I'm in China. Oversea shipping is costy.
And what's worse, is that I might have made a mess. It's not working, yet.
Could be bad PCB manuafacturing, could be bad soldering, or maybe partially wired USB cable. I don't know yet.
Will update later, mmm, when I figure out what's wrong there.

[luma]

  the various silkscreen jokes on that PCB are great!

[whowe]

Check this problem.
Without connecting any satellite adapters. Some channels are high, some are low. Especially the D6, it has a 32MHz (not accurate) pulse. Don't know where it picks up from.
As a reference, a put a 10MHz sine ware on Analog Channel 1. See the screenshot.

[thmjpr]

Check this problem.
Without connecting any satellite adapters. Some channels are high, some are low. Especially the D6, it has a 32MHz (not accurate) pulse. Don't know where it picks up from.
As a reference, a put a 10MHz sine ware on Analog Channel 1. See the screenshot.

This is normal. Once you plug in a working adapter all channels on that adapter should drop low (if its high cable is backwards). I was considering terminating the diff pairs, specifically D6 to try to get rid of this trace "noise" but I got down to 10kR and it was still there so I stopped. Also it would take a ton of resistors.

The issue is some internal noise in the oscilloscope and the fact that they seem to have not pulled/terminated the signal inputs in any way. Which is probably an OK decision if you want to save some cents.

Turn off any channels you are not using to avoid the distraction.

[whowe]

Check this problem.
Without connecting any satellite adapters. Some channels are high, some are low. Especially the D6, it has a 32MHz (not accurate) pulse. Don't know where it picks up from.
As a reference, a put a 10MHz sine ware on Analog Channel 1. See the screenshot.

This is normal. Once you plug in a working adapter all channels on that adapter should drop low (if its high cable is backwards). I was considering terminating the diff pairs, specifically D6 to try to get rid of this trace "noise" but I got down to 10kR and it was still there so I stopped. Also it would take a ton of resistors.

The issue is some internal noise in the oscilloscope and the fact that they seem to have not pulled/terminated the signal inputs in any way. Which is probably an OK decision if you want to save some cents.

Turn off any channels you are not using to avoid the distraction.

Thank you.
When probe 1 (D0-D3) is connected, D0 has opposite polarity than D1-D3. Same thing happens with probe 3 (D8-D11), D11 is opposite to D8-D10. (Maybe the pin definition is incorrect?)
And as probe 2 and probe 4, it's a mess, too much noise, I even can't tell the polarity. Maybe the voltage reference pin is floating because of bad soldering.

The good thing is that I've finally found a USB type-c cable that works.

My bad, I forgot to solder F1-F3 and R5/R6, I thought they're only for the optional MCU. lol

Everything works as expected now!

My next step would be 3D-printing a proper case/handle for the main board.



Again, thank you thmjpr and all other friends who devoted time and knowledge in this thread/project.

[whowe]

A small tip for choosing USB type-c cable: buy those 3.1 Gen2 ones (with or without e-Markers does not matter).
Those cheap ones claimed as "JEM" or "Google" 3.1gen2 cables are known working.
Mine in the attached photo is called Google cable, 0.5M length.


Here's the link for these cables, visit and scroll down you can see detailed pictures (even teardown) of them.
https://item.taobao.com/item.htm?spm=a230r.1.14.16.41cc4735N9EF3q&id=574580414281&ns=1&abbucket=3#detail

[thmjpr]

A small tip for choosing USB type-c cable: buy those 3.1 Gen2 ones (with or without e-Markers does not matter).
Those cheap ones claimed as "JEM" or "Google" 3.1gen2 cables are known working.
Mine in the attached photo is called Google cable, 0.5M length.
(Attachment Link)

Here's the link for these cables, visit and scroll down you can see detailed pictures (even teardown) of them.
https://item.taobao.com/item.htm?spm=a230r.1.14.16.41cc4735N9EF3q&id=574580414281&ns=1&abbucket=3#detail

Thanks, those look like decent cables, incredible for $3-4. Also interesting about the emark chip, it appears to just connect to CC1/CC2, so the only possible issue it would cause would be there, not a big deal.

I've uploaded solidworks files here for a beta case: https://grabcad.com/library/beta-la-case-parts-1 (I think login is needed, can use bugmenot.com). Nothing really holds it together, my plan was to glue it once the board was fully modified.


edit: I may still have D11 flipped on Rev 2, not sure, user WhoAmI has measured it as being OK, thank you.

[hedehede81]

guys, is there an estimate how much it costs right now to make this cable?(counting time as hobby time) is there any possibility we can see a production of these(Kickstarter etc)? or waiting for Rigol cable to go on sale makes more sense?

[joeyjoejoe]

LM7324 is going to be your biggest BOM cost, and then the 4-layer boards themselves (22USD shipped).

I think it's challenging to have someone on Tindie/kickstarter produce this. The demographic is people who are rather experienced/technical, so there's not much value in selling these since most likely the people buying it could make it themselves as well if they wanted to save money. (If they didn't want to save money they'd buy the Rigol unit).

[hedehede81]

For my Fluke 289 there was also a proprietary IR serial cable, which after sometime appeared on Taobao as a bootleg. Maybe this can also make its way some day. As you said, finding LM7324 at a reasonable price point is the bottleneck here, Digikey wants to sell 1000 units to you where as for Mouser international shipping is very expensive. I never ordered anything from TI directly, however I doubt they are cheaper for only 4 chips. If there was an alternative board with LM7322 things can be easier since it is available on Ebay. There is an alternative PCB on gitlab for LM7322 but as an unfinished experiment I think?

[Noy]

Any news here?
Bugs with the wrong signal (high/low) fixed?

In a few weeks i will build a pod but with the "Classic" design. 1 Pod , 2.54mm IPC cable, 1.27mm socket for using my coax cables from the Ds Logic +. And i want to know If there are still some issues with the schematic? The LMs are expensive so hopefully only one shot.

[TopLoser]

Just to try and save people time and effort (and maybe money!)... I have a number of boxed, unopened, Rigol MSO1000Z Upgrade Kits (RPL1116, connecting cable and set of grabbers) for sale.

£95 plus shipping (free UK, £10 anywhere else).

[thmjpr]

Any news here?
Bugs with the wrong signal (high/low) fixed?

In a few weeks i will build a pod but with the "Classic" design. 1 Pod , 2.54mm IPC cable, 1.27mm socket for using my coax cables from the Ds Logic +. And i want to know If there are still some issues with the schematic? The LMs are expensive so hopefully only one shot.

If you are using the Kicad design you will have to fix the swapped +/- of some of the differential signals.

Micro-coax probes is a good idea, although the dslogic has embedded resistance in the connector. So you could consider what effect that has on the signal levels and signal integrity.

[Noy]

Yes i want to use the Kicad Design.
Which differential signals have to be swapped? Is there a list with the wrong ones?

I know about the embedded resistance. I bought a second set of cables and will replace them  with zero ohm resistors.

[memeruiz]

Great thread!

Awesome contributions from dren.dk and later from thmjpr and whowe, thanks guys!

I have seen the gitlab repo from dren.dk, but not the one with the USB-C modifications. Is it somewhere? Would be nice. Maybe I can make some contributions to that version.

Thank you!

[thmjpr]

Yes i want to use the Kicad Design.
Which differential signals have to be swapped? Is there a list with the wrong ones?

I know about the embedded resistance. I bought a second set of cables and will replace them  with zero ohm resistors.

You'd have to compare the connector pinout to what is shown in Rev 2 schematic. I was told the pinout is correct by users above, but I have not personally tried that board.

Great thread!

Awesome contributions from dren.dk and later from thmjpr and whowe, thanks guys!

I have seen the gitlab repo from dren.dk, but not the one with the USB-C modifications. Is it somewhere? Would be nice. Maybe I can make some contributions to that version.

Thank you!

thank you, https://gitlab.com/thmjpr/stm32f03_la_monitor

If you need any specific info/files let me know via PM.

[Rerouter]

If it was my version, looking way back at my last upload, I did have pins flipped, and looks like I never uploaded after fixing it, so here they are minus the last few connections I got stuck on.

If the other, If you can point me to what is wrong, I should be able to correct them,

[Gandalf_Sr]

I've been looking at this thread with interest; I'm close to ordering an MSO5074 but I'm not keen on paying an extra $360 for the PLA2216 cable (36% of the cost of the scope).  I looked on Digikey and there are other LVDS comparators available although many seem nearly as expensive as the TI part suggested.  The difference in price between the MSO5074 without/with the PLA2216 is $360 and you can buy the probe on its own for $400 so I may well just buy without for now.

So I'm considering a poor man's logic probe that would be good for up to 100 MHz ish, I realize low propagation delay may be a necessity for digital timing alongside the analog signals but some logic families such as TI's AUC go down to 1.5 nS propagation delay although I think that the MSO5000 needs +/- LVDS signals.

Then I looked on TIs website and came up with the DS90LV047A 4-channel LVDS driver IC which are $2.62 each so about $11 to get 16 channels, and have a 1.7 nS propagation delay, that's more like it!

Anyone think this could work?  Tell me I'm insane but, if this is a reasonable idea, let's get the circuit designed! I will create the schematic do the PCB layout in Diptrace.

[MarkL]

...
So I'm considering a poor man's logic probe that would be good for up to 100 MHz ish, I realize low propagation delay may be a necessity for digital timing alongside the analog signals but some logic families such as TI's AUC go down to 1.5 nS propagation delay although I think that the MSO5000 needs +/- LVDS signals.
...

Just a comment on the propagation delay...

If you're concerned about matching the analog channel delay to a home-brew digital probe delay, the Rigol 5000 has a channel delay adjustment.  It's not clear from the user manual if you can adjust the digital channels, but you can certainly move the analog channels relative to the digital.  And although it doesn't say, I'm a sure a few nanoseconds would be within its range.

Most scopes have this, even old analog scopes.  Also known as channel-to-channel skew adjustment.

[Gandalf_Sr]

OK, here is the simplest form I can imagine for my design idea:

1 There could be 4 x DS90LV047A converting single-ended 3.3V CMOS logic levels into LVDS differential signals.  Cost about $11
2. A single 74AUC16244 acting as a 16 bit buffer and voltage level translator following the advice in the TI little logic guide starting on page 19.

The AUC device at 2 above could be multiple devices e.g. 4 x 4bit buffer.

The different voltage levels being sensed could be handled by different Vcc values used for the AUC buffer.  How did the original design do this and was there some sort of setting in the MSO5000 to define what was being sensed?

If the DS90LV047A devices convert single ended into LVDS signals then I think it makes more sense to have them on the smaller PCBs close to the point of sensing and then send LVDS signals over the ribbon cable to the board that plugs into the MSO5000.

What about the input protection circuitry?

Comments please.

[Gandalf_Sr]

OK, to self-comment.  I've been looking for comparators that would be a front end for the DS90LV047A but they are either too slow or too expensive so the LMH7324 seems like a good option and, at 700 pS propagation delay, it's the fastest that TI has listed.  However, the minimum Vcc is supposed to be 5V, was that catered for in the designs you guys have implemented?

[TopLoser]

There's only a maximum of 4V supply available on the scope connector.

Start reading the thread from the beginning, it's got answers to lots of your questions.

[Gandalf_Sr]

There's only a maximum of 4V supply available on the scope connector.

Start reading the thread from the beginning, it's got answers to lots of your questions.

I've read the whole thread a couple of times.  I saw the comment that the comparator only had 4V and needed 5.  Someone responded that there was a -2.1V available on the scope connector which could be added to the +4V, so in the designs, does the comparator run on 4V or more?

Maybe it runs OK at 4V?