Low Cost / Compatible Rigol PLA2216 Logic Probe for DHO900 (and Hacked DHO800) - Page 1
Forum section: electronics / testgear

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 08, 2023, 06:59:47 pm
content: 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-teardownhttps://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/#msg2419002many 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..

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 24, 2024, 12:06:07 am
content: 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.

author: AceyTech
author_rank: Regular Contributor
timestamp: February 24, 2024, 05:15:29 am
content: Quote from: Mechatrommer on February 24, 2024, 12:06:07 amWell 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)

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 24, 2024, 05:20:33 am
content: Quote from: AceyTech on February 24, 2024, 05:15:29 ami 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.

author: antiquant
author_rank: Contributor
timestamp: February 24, 2024, 08:21:16 am
content: 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!

author: gabiz_ro
author_rank: Regular Contributor
timestamp: February 24, 2024, 09:57:05 am
content: Looks like is missing.Only photo I could find.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 24, 2024, 02:00:46 pm
content: Quote from: antiquant on February 24, 2024, 08:21:16 amgreat! looking forward to see the original probe in action on DHO800 hacked.Quote from: antiquant on February 24, 2024, 08:21:16 amfor 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 posthttps://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/#msg5352692anchor related post #2:https://www.eevblog.com/forum/testgear/hacking-the-rigol-dho800900-scope/msg5355353/#msg5355353

author: S2084
author_rank: Regular Contributor
timestamp: February 24, 2024, 03:18:24 pm
content: How nice it is to see a person who actually does something, and doesn’t just talk.... You’re great.....

author: LEER333
author_rank: Contributor
timestamp: March 22, 2024, 01:43:26 am
content: Hi！My DHO814 does not have -2.5V, and the measured voltage is -4.48V. Does it affect the normal operation of the circuit?

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 22, 2024, 05:16:11 am
content: Quote from: LEER333 on March 22, 2024, 01:43:26 amyes 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.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 25, 2024, 04:03:56 pm
content: 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...

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 28, 2024, 07:47:01 pm
content: i think some people got mental crack when selling stuffs. how could just a flying lead costs much more than an oscilloscopehttps://www.ebay.com.my/itm/374661266605https://www.ebay.com.my/itm/386270648907https://www.ebay.com.my/itm/265359849711this one much reasonable..https://www.ebay.com.my/itm/175950092028is it like thick gold in there?https://www.techtravels.org/2021/02/hp-agilent-5382a-tear-down-with-photos/

author: Aleksandr
author_rank: Regular Contributor
timestamp: April 30, 2024, 10:45:01 am
content: I was planning to assemble a logic analyzer for DHO924, I ordered LMH7322 microcircuits, but I had questions about the circuit and resistor values! 1. What is the value of the resistors in the 497 Ohm circuit? Are these available for sale? Or is there something else there? And such a question regarding the denominations 7.98k, 90.8k, which ones should be best set there??? 2. Is the CONF output connected somewhere for the DHO924?

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 30, 2024, 12:29:09 pm
content: Quote from: Aleksandr on April 30, 2024, 10:45:01 am497 means 497Ohm, 7.98k means 7.98kOhm, 90.8k means 90.8kOhm, you can find closest value in lcsc.com. CONF not applicable in DHO800/900...

author: fuzzoli
author_rank: Regular Contributor
timestamp: October 21, 2024, 06:45:31 pm
content: HI Mechatrommer. Is there a project page for the schematic, pcb, gerbers, etc. and the Rev 2 board? Thanks!

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 22, 2024, 09:57:33 am
content: schematics already up there... the exercise will be to make the pcb, its not that hard... just copy paste 16 times...

author: kangalooj
author_rank: Newbie
timestamp: December 28, 2024, 04:14:44 pm
content: Hi @Mechatrommer, did you ever consider TLV3802 ?It would be cheaper, and much less pins to deal with and smaller footprint and a perfect layout would be possible!My only concern is the output of this chip is LVDS instead of RSPECL!Any thoughts?

author: GhostInTheDatacenter
author_rank: Newbie
timestamp: September 01, 2025, 08:29:24 pm
content: Has anyone tried this design lately? Could you sub the LMH7324 for the LMH7332?TIA!

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 06, 2025, 07:51:02 am
content: Quote from: kangalooj on December 28, 2024, 04:14:44 pmnice alternative for half the price. but extra work and components to level shift LVDS to RSPECL. my idea was to make 1:1 as original at fraction of price. LMH7322 is expensive, but original rigol unit is more expensive still... cheers.