Metrix OX 2000 digital oscilloscope - Page 1
Forum section: electronics / repair

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 16, 2018, 09:13:36 am
content: I recently bought a couple of these DSO's plus spares, they are 4 channel full digital oscilloscopes with 150MHz bandwidth and 200MS/s (?) sample rate.Thy have GPIB and RS232 connectivity, internal monitor is a green CRT, there is also a VGA output with non-configurable color for the traces.I have:1 repaired skynet PSU.2 green VGA monitors, only one tested so far.3 frontend boards, 2 are working with cal. errors, one is beyond repair due to something serious happening on the PSU.3 CPU/Acq. mainboards, only one tested and appears to be working normally so far.3 Front panel boards, only one tested so far.The first aim is to get one fully working scope out of all this before trying to throw a second one together, not an easy task as there is no service information out there.The F.E. boards are both failing the self test "randomly" mostly for bad offset on most channels but also for bad gain at times on some channels.I'm suspecting the relays could be the cause for the gain fails although all the N.C. contacts measured a decent resistance so far.Each channel has:Two RA12W-K, three A12W-K and one Hamlin (Littlefuse) HE3651A6490 reed relay.One AD711KR fast OP-AMPOne TL084CTwo SL3227One SL2364COne MC14053BOne ULN2003A (relay drive).There is some time sharing as CH1+CH2 are sent to one ADC (AD9002AJ), CH3+CH4 are sent to another ADC on the acquisition board, there are only 2 ADC's.I haven't identified where the switching happens yet, the last chunk on F.E. before the coax to the Acq. section is mainly discrete.Any clues on what to look for and how this could all tie together are welcome!Scans of the F.E. board here:https://photos.app.goo.gl/lsmE1pMSz0d0s6Sx2https://photos.app.goo.gl/vJFXiwfXi71yETf73

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 18, 2018, 02:02:20 am
content: BUMPStill playing around with these, it really looks like the person who sold them threw all the worst parts of a dozen identical scopes together, then threw the scopes on fleabay so I could have hours of fun for a moderate price.Getting in touche with Chauvin-Arnoux or Manumesure has not helped in any way so far.All the same I seem to be getting somewhere, although the one I've been working on so far was failing self-test randomly on all channels, it is starting to look like it was mainly out of calibration. The last cal. dating back to 2011.After many hours of trying to follow tracks around the F.E. board, I have a very slight better understanding of the machine.I have also dumped the two 27C4001 EPROMS, grouped them as a single 16bit image and found in the text strings that there was a hidden FULL 45" CALIBRATION (!) other than the FAST 5" CALIBRATION in the user menu. (Think SPC on the Tek scopes.)The point of leaving the 5" Cal. accessible to the user is that these bi*ches drift a helluvalot! Of DSO's of the same era I still find the LeCroy 9300's did best with their automatic re-cals freezing the UI for a few seconds.Also desoldered, dumped, socketed the M28C64C EEPROM holding the cal. data before finding the way to access the full cal. menu and fooling around with it.

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 30, 2018, 09:24:29 am
content: The only documentation I've found on this DSO is the attached commercial overview.It mentions a 200MS/s rate on CH1, and 100MS/s on the remaining three channels.I can understand how the acquisition system could be combined to reach 200MS/s when only one channel is used (two AD9002 ADC's are used in here) but no matter the setup the single shot acquisition remains the same.The brochure also states FFT in the math functions, nowhere in the scope's menu or even searching the ROM dump can I find FFT. Maybe this required another ROM version...I almost have two working scopes, all I'm missing now is a second PSU of course they are the main failure cause and pretty much unobtainium.Outputs on the original PSU are rated at:-16V / 0.7A-5.2V / 5A+5V / 3.5A+14.5V / 3.5AThey all have OCP and possibly OVP.I have not yet measured actual current on each rail.I'm either thinking of using a cheap MeanWell 24V PSU (that I already have) followed by independent buck regulation for each rail or re-wiring (re-winding) an ATX PSU to suit the job.Given I have plenty of repair experience (including SMPS) but little design experience, which option would be more reasonable?(Unless anyone has a suitable PSU for sale of course...?)

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 30, 2018, 11:45:47 pm
content: Here are the real life current requirements for whoever needs to know:-16V / 0.8A-5.2V / 4.6A+5V / 1.3A+14.5V / 3.12ATotalling around 90W, that's without PCMCIA card inserted and without using any ports.

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 04, 2018, 10:25:49 pm
content: Still updating for the sake of documenting the instrument a little.The SkyNet AKE-9110 SMPS runs at 60kHz, the primary side PWM is a SK-6080, a custom design from Unitrode for SkyNet. (About the same era there were also similar PWM custom designed by Fuji-Electric with the same SK-xxxx part numbering)Auxiliary supply for housekeeping is +7.1V from a separate transformer.Main supplies come as -17.3V, -5.4V, +5.7V, +15,41V before LDO linear regulation using MOSFET's.Positive supplies share a common ground right from the main transformer, negative windings are independent allowing to use N-MOS pass transistors on the "high" sides of the negative rails before the regulated high side joins the common ground.Power rails do not appear to have any predefined startup sequencing.Line trigger output is built around a Sharp PC900V opto.

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 06, 2018, 05:27:21 pm
content: People, I'm feeling lonely here!https://youtu.be/OdqC9nBVFFQOh well I found this video remotely appropriate...Here goes a bit of reverse engineering: The line trigger section and the -16V regulation. The PSU has 4 similar regulator daughter boards, the only changes are resistor values to adapt the voltage range. The negative rails have ZD1 in place the positive ones have it shorted out.I hope I got my schematic right as this is intended to becomethereference topic on this oscilloscope.

author: cheeseit
author_rank: Regular Contributor
timestamp: June 06, 2018, 06:19:39 pm
content: I don't have anything to add but you're not alone so please continue updating as I enjoy reading repair stories like this

author: Vince
author_rank: Super Contributor
timestamp: June 06, 2018, 09:36:40 pm
content: Hi Paul !Looks like you have just got yourself yet another challenge !A full blown Metrix DSO without a service manual, as "always" with Metrix stuff... you like a challenge don't you ?!I must say I am overwhelmed... you have two scopes and so many spares, I am not even sure I understand what it is exactly that you are trying to fix at the moment ? ... What board, what fault ? Do you have a fully working scope and using it as test bed to fix all your spare boards one by one, each at a time ?!Anyway, it's late and I most likely should not be reading your topic, seeing as half my neurons are already in deep sleep mode... doesn't help.I see pictures of the FE board... I also see lots of pesky electrolytic caps !I assume you have already recapped that board, and searched real good for any signs of corrosion around all these caps ? Solder joints that look a little bit more dull than the average joint on that board ? I am sure you did... sorry for thatBut on my TDS 544A remember, when it failed again after a year or so, with all sorts of weird and wonderful error messages... it was all fixed just by reflowing a handful of slightly dull looking solder joints on a few passives ! So it really doesn't take much at all to upset these complex boards...Anyway, just saying that since you don't have any schematics, it's even more vital not to overlook the basics... especially as it might be all it takes to fix that board... simple things first !Anyway, I wish you the best of luck, will be following your progress, I want to see the gory details of your fight, and ultimately how you will win ! Because you WILL win ! You always do. Might take a " Minitel " (1) to fix it, but you will fix it, I am sure of that !(1) Private joke, sorry !As for me, I prefer simple things. Look what I just bought last week, a Tektronix 2215, fixed it last night for literally 10 cents, the price of a Zener diode !https://www.eevblog.com/forum/repair/tektronix-2215-scope-repair/msg1591156/#msg1591156Keep us posted Paul, don't give up on it , we are all watching your progress !

author: shakalnokturn
author_rank: Super Contributor
timestamp: June 07, 2018, 11:34:08 pm
content: Thanks for the encouragements!I do realise my first post was not that clear...I first bought one full DSO in good cosmetic state but not working. Seller specified that two transistors were missing on the PSU.When the scope arrived I replaced the missing transistors and tried to power-up, it was dead. Did a little testing around for shorts on the PSU itself and on the Acq./CPU board where the PSU connects. Nothing obvious.Looking closely at the brown Nichicons on the PSU there were dull grey solders around, the PSU has many hot spots and the smaller electrolytics were very compact models often squeezed into those hot spots.Replacing most of them brought the PSU back to life, and the scope powered up displaying the boot splash screen with a distorted picture (monitor problems to see to later...), the traces were not on screen though, shortly after the scope restarted and appeared stuck in a boot loop, I started investigation on the CPU reset (TL7705AC), but before long there was no display at all and the PSU was hiccuping.Checked for shorts at the PS connector again, nothing too obvious, found the rail that looked lowest and gave it a push with the lab supply. Display came back up, no traces though...So then I went for a first peek at the frontend board on the down-underside (not far off Australia) of the scope, uncovering there was a nice spluttered burn mark on the aluminium shielding.That turned out to have previously been a 0ohm SMD on one of the 5V rails, on the underside (getting way down south!) of the frontend PCB same scene, another fused 0ohm resistor.This one was on the ground though (not something I'd recommend in any design...) I'll never know what the original problem was, but possibly thanks to blowing this ground link, among other-things the AD767 and the P87C52 were gone making any repair hopeless.I had a quick look for another parts scope and the same seller was selling another in poorer cosmetic condition, missing PSU, fan, but with spare parts: An extra frontend, front panel and Acq./CPU board.I'm guessing that these two scopes plus spares were the worst parts the seller had left after rebuilding a few scopes swapping boards around.However, a week later I had more junk to play with and with a "new" F.E. board a scope now showing 4 traces, although 2 are often so far offset that they can't be seen.From one 5" calibration followed by self test in the menu to the next, the results are not the same.Things are looking like either automatic calibration failure or self test failure.From there I checked as many supply voltages and ripples as I could find, basically at all electrolytic capacitors on Acq./CPU and F.E. boards, nothing really worrying, I did hesitate a little at 60mV spikes on a 8V supply, the caps were OK though.Resoldered the whole worst channel, tested and swapped some relays, things did get a little better, still far from good.I had dumped the EPROMS right at the start but being high and low data separately for a 16bit SCC68070, they needed to be grouped as a 16bit image before looking for any meaningful text strings. Anyway, a Full 45" calibration did show-up in the dump, so I then desoldered and saved the EEPROM containing the calibration data just in case...After that I found the way into the cal menus, did a pinch of manual calibration (AD767 reference and frequency compensation on one channel) and let the 45" calibration see to the rest. It does the job by itself, although 45" takes forever....After that all self tests passed time after time on a warm scope, a cold scope will fail offset on all channels, but I'm guessing that is why the 5" cal was left accessible to the user, to compensate the drift when needed.(Right, being used to LeCroy this sounds awfully awkward, so I feel I must quote another manufacturer for clarification: SPC is the acronym for Signal Path Compensation. SPC's. Running Signal Path Compensation corrects for DC inaccuracies caused by temperature variations and/or long-term drift. The benefit of running SPC is that is optimizes the oscilloscope's capability to make accurate measurements based on the ambient temperature.)So from there I considered I had working scopes, as they were happy with their self-tests and conforming to my own checks.Note that at the best, DC balance is poor on these OX2000 scopes.All the monitor took was a good spraying and reajustment.In the end I don't think I actually repaired much other than the PSU, but considering there is not even a user manual to be found on the WWW, it was a handful to actually look for a way to get at the calibration rather than go round in circles looking for a fault that wasn't there without schematics. (I did a few hours of circling all the same!)I do like the challenges Vincent(Sorry long post...)So now all I need is a PSU for the second scope, the easy way out would be using one of the spare TDS400 PSU's I have around, I/V requirements for each rail are similar enough, they also have the line trigger circuitry, all the same I'd like to see where I get with a modified ATX supply.That will be later though, for now I have a leaky TDS620 I want to get out of the way before it corrodes through to OZ land, I just hope it won't turn out to need a sacrificial Minitel too.

author: Vince
author_rank: Super Contributor
timestamp: June 08, 2018, 06:21:25 pm
content: Wow... loved the story !Yes, long, but hardly boring, was captivating...In your first message, I was left with the impression that you basically were facing a huge pile of hopeless junk boards, desperately trying to get anything good out of it...... so in your last message, I was literally taking notes in Notepad, to keep track of what boards you have, their symptoms, what work was carried out.... then in the last few lines, that huge pile of junk suddenly turned into a couple of working scopes, and that you don't need any help any more !See, I told you you would win ! I just did not anticipate you would win THIS fast !You are my hero !I hope one day, I will be 5% as talented and successful as you consistently are !Boy, you are giving me the motivation to get back to my TDS 310 ! I blew the hell out of the primary side of the SMPS... will try to rebuilt it (again, no documentation on it, as you know, third party etc etc..). Then if I can find a spare membrane keyboard for the bezel, scope would be fixed...Do update this topic when you get round to transplanting that TDS400 SMPS, wanna see that !Good luck with the TDS 620... I hope for you that it's not as far gone as "our" TDS 544A !And if you ever get your hands on a cheap TDS380 (400MHz 2GS/s), think of me, I want to add one to my ever growing "collection" of (mostly) Tek scopesRight now, a guy on LBC is selling a few of them, working, pristine, for 250 Euros.. for once it's somewhat reasonable I find.. but I don't have that kind of pocket money right now, sadly... in a year maybe.

author: alitronix
author_rank: Contributor
timestamp: November 25, 2024, 09:48:55 pm
content: Hello,I know it's been a long time since the last post. :'(But maybe if we warm up the topic, someone else might have gotten their hands on one of these scops and come up with another story...Now, what was the end of your story? Do you still have one of these?Quick question: Have you found any manuals for the OX2000, even just the user manual? I believe it uses a PCMCI 1 memory card (the first generation, totally flat one) with a capacity of up to 1MB, right? I’ve noticed they’re quite expensive now...I have one too, and the documentation for it is... nonexistent. I haven’t been able to find anything useful on the web. Why? Metrix is (or was) a quite good brand for professional work, right?I did manage to repair the PSU once and performed a full recap , nothing else done with it. Of course, it works well as a second scope, though there’s a bit of noise. I’m thinking about changing the fan for a quieter one, but for now, it's fine as it is—like a helicopter!I really love these scopes—they're very easy to use and perform well for their specs.If I remember correctly, the CRT monitor can be replaced with an TFT monitor since it has a color VGA output, so it's easy to do. Similar to how the upgrade to a TFT monitor can be done on Tek scopes, correct me if I'm wrong. Of course, there isn't an official upgrade kit for this, but with a bit of imagination, the right size TFT screen, and some 3D printing, the job can be done.I'll open it one day to check this and also to change the fan.

author: shakalnokturn
author_rank: Super Contributor
timestamp: November 26, 2024, 12:10:23 am
content: So you're the second or third and possibly last owner of one of theseIt was the end of the story, I sold the repaired scope and moved on to something else.I have a second one around still not got down to finding a PSU.Still no documentation at hand either.Metrix have made some decent equipment, I've never been impressed by their oscilloscopes though, not until the Scopix series.The OX2000 must have been very expensive, maybe not so attractive compared to what Tektronix and HP had to offer, I doubt they sold many...The PCMCIA card slot is very likely to require linear SRAM exclusively, they're the ones with a backup battery that were used on some musical equipment and on the later Amiga computers as RAM expansions (there are a couple of DIY projects for that).Yes, they're too expensive, no clue about the maximum supported capacity.The colour LCD modification should be easy enough.

author: alitronix
author_rank: Contributor
timestamp: November 26, 2024, 09:00:51 pm
content: I’m the last Mohican... I will never give up! I’ll take a Metrix oscilloscope with me to my tomb...)Better... later, I’ll set up a Metrix museum...Okay, aside from the jokes, I’m not a blind Metrix fan, but I find their oscilloscopes very easy to use, they work well, and why not, they look nice too. And with all the features they had for the era when the OX2000 was launched, wasn’t it one of the top scopes? I believe so. I remember in the 90s and 2000s, when I was younger, I dreamed of owning one of these scopes.Off-topic: I own/owned, just like you and others, oscilloscopes from different brands, like Tektronix, Lecroy, Agilent, HP, and others, including some lesser-known brands. I’ve owned almost every model well-known among hobbyists, like the Tek 2222 and older ones , 340, 430, TDS series, HP 54600, Hameg, and more. If you check eBay regularly, you can find everything for a small price... it just takes patience. Over the years, like you and others, I’ve changed scopes a lot, but still, I find the Metrix scope (made in France) to be much more reliable than Hameg, for example... though maybe that’s just personal preference.Honestly, I understand why people are loyal to certain brands... everyone has their preference.For example, right now I have Metrix OX2000, OX803B (just for component testing), OX8062 (for differential input), and OX863B (luckily, I have space and room for equipment, not just for hobby). They’re cheap because no one wants them...What I don’t understand is why so many people are fixated on Tektronix, HP, or Fluke. Many people (who call themselves EE engineers) don’t even know how to use their tools, but they have the most complicated—and sometimes in bad condition—scopes, just because they’re branded.And I have news: I wrote to Chauvin Arnoux Italy (I’m based in Italy) again after a year or so when I tried first time when they didn’t respond to me. Now, they kindly responded and even sent me a ZIP file with some documentation in English (what is GOLD, now) that they recovered from old files they had. It includes some Word files (non-editable and printable) with a good part of the OX2000 manual. While digging a little, I found some interesting notes...Now, I’m working to put everything together and create a PDF file. They told me this is all they recovered and that no further documentation is available (at least not here in Italy).I found that these scopes were made by BOONTON, and the model was called DIGISCOPE 2000.If you’d like, I can send you the ZIP file, and you can make your own manual, or once I finish putting it all together, I can send it to you. It’s not a service manual, just a user manual. It’s not much, but still, going from nothing to having a manual in two days is a good start. Now, I’ll do my research on the DIGISCOPE 2000 or the Boonton scopes too.Man, the PCMCIA SRAM cards are around 100 euros... way too much to invest just for this scope. The internal memory is good enough to store waves and configurations. Since it’s not my main scope, I’m not really interested in saving the waves. If I need to, I’ll just do like in the old days and take a picture...I hope I’ve stirred up some feelings in you, and you’ll give the scope a try!)