Low Cost / Compatible Rigol PLA2216 Logic Probe for DHO900 (and Hacked DHO800)

[Mechatrommer]

Rigol DHO900 supports PLA2216 logic probe. but when i check pin's voltages on power rails and references, i got quite different values compared to other people's finding. but i'm doing this on hacked dho804 to dho924S FW. i've put opa2350 opamp as replacement of missing opamps labelled b,c (originally TP1282 opamp i suspect but now its unobtanium) and placed MPM3630 on footprint labelled a, now i got 4V rail and some references. the differences are power rails i measured are ±4V and +2.5V where other members measured ±2.5V and 4V combination (please refer to LA_header_rig.PNG and LA_header_rig (dho800).jpg) the other difference is reference/trigger voltage i measured is not 1/10X of actual trigger as others measured. i measured for trigger setting of 15V in DSO GUI, Vref output to the probe is -1.2V and for trigger -15V, Vref output is -2.7V or somewhere there, its quite weird, if this is confirmed with other DHO900, then i have to make different offset circuit in my diy probe. but if my offset is not correct, maybe its due to opa2350 that i used... if people can cross check, i will be glad. cheers.

reference:
https://www.eevblog.com/forum/testgear/low-cost-logic-analyzer-probe-for-rigol-mso5000-easyeda-project/
https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown
https://www.eevblog.com/forum/testgear/ms05000-budget-logic-analyzer-probe-set-design/

LA_header_rig.PNG attached i got from:
https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/msg2419002/#msg2419002

many NCs in LA_header_rig (dho800).jpg mean"not checked" or "not verified" yet. 8pcs LMH7322 is on their way from Mouser, i'm not going the cheapest route, i'm going the "fully compatible but cheaper" route, for (a bit expensive) learning adventure... fwiw...

UPDATE: i add extra attachment on updated findings dho800 vs dho900 pcb fwiw..

[Mechatrommer]

i finished my "barebone minimum functioning" of "full functionalities cloned" PLA2216 LA Probe for my DHO800.. it can be calibrated from dso, read 16 channels, ±40V input range and adjustable threshold (trigger level), without the need to install the missing 2x DDR3L RAM on DHO800, success!!! thanks to all contributing, attached are pictures and references i used from the linked threads/posts in OP. next step will be to design 3d printed enclosure for it. cheers.

[AceyTech]

i finished my "barebone minimum functioning" of "full functionalities cloned" PLA2216 LA Probe for my DHO800.. it can be calibrated from dso, read 16 channels, ±40V input range and adjustable threshold (trigger level), without the need to install the missing 2x DDR3L RAM on DHO800, success!!! thanks to all contributing, attached are pictures and references i used from the linked threads/posts in OP. next step will be to design 3d printed enclosure for it. cheers.

Well that is fantastic news, my friend!  Good job getting that operational.  I had a larger post worked up before you located the soldering error.  I was going to offer "a second set of eyes" as to your setup and testing apparatus, etc.., because I was very concerned about resurrecting the "need for the missing DDRam" conversation.

One thing I was going to ask, and is still relevant: Does your probe work on a regular mixed sig DHO unit?(I.e., not a hacked 800 model)

[Mechatrommer]

One thing I was going to ask, and is still relevant: Does your probe work on a regular mixed sig DHO unit?(I.e., not a hacked 800 model)

i dont know, i dont own DHO900.. but looking from the similarity of pins interface among DHOs/MSOs, i cant think any reason why it cant be used on other MSOs/DHO900 that support the interface as well. cheers.

[antiquant]

That's wonderful news!
You just nailed it!

I have PLA2216 and DHO804. So I want to try the LA probe with hacked DHO.

Mechatrommer, tell us, please, did you add an unpopulated (missed) bulky surface mounted diode above that two op amp ICs? And why are the TP1282 dual op amps ICs unobtainable?

Is that diode present on DHO900' PCB? Does anyone have a clear pictures (or scans) of DHO900 series PCB (DHO914(S), DHO924(S))?

Thanks for your work!

[gabiz_ro]

Looks like is missing.
Only photo I could find.

[Mechatrommer]

I have PLA2216 and DHO804. So I want to try the LA probe with hacked DHO.

great! looking forward to see the original probe in action on DHO800 hacked.

Mechatrommer, tell us, please, did you add an unpopulated (missed) bulky surface mounted diode above that two op amp ICs? And why are the TP1282 dual op amps ICs unobtainable?

for LA to operate on DHO800, in HW level you'll need to install:
1) 2x TP1282 designated b and c in OP picture (i replaced them the with 2x OPA2350)
2) 1x MPM3630 (intended for 4V rail to the LA probe)

and you need to go through this process (now i'm publishing it here)


TP1282 is not available anywhere the time i checked for it, but since i have OPA2350 in stock (and available anywhere and aliexpress), looking at spec is not too far off, so i tried it and afaik is a success! i guess other dual opamps with similar vssop footprint can be tried ymmv. MPM3630 is available in aliexpress. it is used as 4V rail to LA probe. installing it is quite tricky, so i'm providing plan B to supply that rail from external 5V powerbank trough USBC connector, if anyone are not willling to install MPM3630 internally, see attached circuit (advises welcomed). you can also see where the USBC connector in above attachments.



the difference between dho800 and dho900 pcb (missing components) are highlighted in post https://www.eevblog.com/forum/testgear/hacking-the-rigol-dho800900-scope/msg5339129/#msg5339129 (let me update the attachment in OP) mainly which i think affect functionality/feature of the scope... few (4x) TP1282 opamps are missing and 1x MPM3630 and few IDC connectors. and also the 2x DDR3L RAM, i think other missing components on dho800 also missing on DHO900... fwiw ymmv..

edit:
anchor related post #1: https://www.eevblog.com/forum/testgear/hacking-the-rigol-dho800900-scope/msg5352692/#msg5352692
anchor related post #2: https://www.eevblog.com/forum/testgear/hacking-the-rigol-dho800900-scope/msg5355353/#msg5355353

[S2084]

How nice it is to see a person who actually does something, and doesn’t just talk.... You’re great.....

[LEER333]

Hi！My DHO814 does not have -2.5V, and the measured voltage is -4.48V. Does it affect the normal operation of the circuit?

[Mechatrommer]

Hi！My DHO814 does not have -2.5V, and the measured voltage is -4.48V. Does it affect the normal operation of the circuit?

yes i guess its normal, i think it will determine -ve input range to -40V. if you can see in connector diagram above and schematics (VEE), its different from another scope. power rails are 4V, -4V and 2.5V.. if probe not properly calibrated, Vref1 and Vref2 will also floored to -2 or -4V or something. fwiw.

[Mechatrommer]

since someone asked in PM... just an update... i'm currently waiting my pcb rev 2 (not much different from rev1 visually) due to some careless mistake made in rev1. and i try to make a 3d printed enclosure for it, see attached images, just for food of thought in case someone want to do the same...

[Mechatrommer]

i think some people got mental crack when selling stuffs. how could just a flying lead costs much more than an oscilloscope
https://www.ebay.com.my/itm/374661266605
https://www.ebay.com.my/itm/386270648907
https://www.ebay.com.my/itm/265359849711

this one much reasonable..
https://www.ebay.com.my/itm/175950092028

is it like thick gold in there?
https://www.techtravels.org/2021/02/hp-agilent-5382a-tear-down-with-photos/