What is PowerScope  - Page 1
Forum section: electronics / beginners

author: yashrk
author_rank: Frequent Contributor
timestamp: April 11, 2014, 09:16:35 am
content: One of mine friend scored some test equipment called "881a PowerScope by McVan Instrument" , I want to know weather its an oscilloscope or something else. If it is something else then for what it is used ?

author: johnwa
author_rank: Frequent Contributor
timestamp: April 11, 2014, 09:47:26 am
content: Hi,These are oscilloscopes specifically designed for working on high voltage, high power/three phase systems. One model had four fully isolated and floating channels, and I think they are double insulated as well. I don't think the bandwidth is much to write home about, but it would be OK for low frequency work at least.

author: yashrk
author_rank: Frequent Contributor
timestamp: April 11, 2014, 10:01:35 am
content: So I can use it like a normal oscilloscope right ? can you suggest me some probes for it ?

author: johnwa
author_rank: Frequent Contributor
timestamp: April 11, 2014, 10:14:18 am
content: Yes, you should be able to. I am not entirely sure about that model, but I think the one I remember just used banana plug sockets. You can make up some leads out of coax cable, with banana plugs at one end, and crocodile clips or whatever at the other end. This should be OK, say, for below 1MHz. You might want to check the input impedance, as it is possible it may be something non-standard.

author: GK
author_rank: Super Contributor
timestamp: April 11, 2014, 11:16:24 am
content: The 881a was originally made down here by BWD Electronics, which was apparently bought out by McVan. BWD history:http://en.wikipedia.org/wiki/User:Mosfet_RJF/BWD_ElectronicsLots of pics of it here:http://www.iowa-industrial.com/Tristate-Area-/Metalworking-and-Production-/Numberically-Controlled-Equipmnent-/Bwd-881A-powerscope-ii-tested.cfmFrom memory the only thing special about this scope was the vertical channel inputs, which were differential and designed/insulated to be safely connected to the mains. An Electricians scope

author: miguelvp
author_rank: Super Contributor
timestamp: April 11, 2014, 06:00:41 pm
content: Wow, 200V to 20 mV per division!1 second to less than 1us time division.not sure what the min time is -5 is that half 1us? and then a -2, so It might do 4MHz BW?

author: yashrk
author_rank: Frequent Contributor
timestamp: April 11, 2014, 06:17:29 pm
content: @miguelvp I didn't got what you want to sayIs it good or bad ?

author: miguelvp
author_rank: Super Contributor
timestamp: April 11, 2014, 08:36:07 pm
content: Actually made a typo, I meant from 200V to 20 uV per division!and it means that I'm impressed, never seen a scope that can do 200V per division directly. I mean we can get high voltage probes sure, but this can handle it inside it.As for good or bad, you can't use this for fast signals over 4MHz, but for electricity, power supply stuff and analog audio it should be just fine.For electronics you can use it as well, I2C for example is 400KHz so it will work with that too, so it will with RS-232 and many other things in electronics.So what I meant was surprised by the specs, as in bad or good, it has its place. Someone that works on old pinball machines would love to have a scope like that I bet.

author: yashrk
author_rank: Frequent Contributor
timestamp: April 12, 2014, 11:29:09 am
content: @miguelvp thanx

author: yashrk
author_rank: Frequent Contributor
timestamp: April 12, 2014, 05:52:25 pm
content: This scope is a pain in the a##, friends do you know where I could get manual for this oscilloscope (Bwd 881A powerscope ii).Please I need it to understand all its functions.

author: miguelvp
author_rank: Super Contributor
timestamp: April 12, 2014, 06:55:45 pm
content: Only hit I get for the datasheet (not the manual) is:http://www.prime-electronics.com.au/datasheets/data/BWD/881A%20Powerscope.pdfBut they have removed it, there was another site that also had it and removed later on as well.Only manuals from that manufacturer that I can find is:http://bama.edebris.com/manuals/bwdBut nothing to do with the PowerScope, those are they previous regular scopes.QuoteOne thing that can help is to post a picture of the full front/back and sides (if any connectors are on the sides) and people could tell you what is what.

author: yashrk
author_rank: Frequent Contributor
timestamp: April 13, 2014, 10:15:58 am
content: Sure will share its photos also

author: RJFreeman
author_rank: Regular Contributor
timestamp: October 29, 2014, 01:44:06 am
content: Sorry for the late arrival but I have played with and own a BWD 881, although to be honest it is a year or two since I fired it up.off teh top of my head it can be driven as a normal oscilloscope, only with differential inputs on two modified BNC type connectors.to use regular CRO probes I purchased male BNC to female BNC adaptors off Ebay and used a hacksaw to cut off the bayonet latching ring on the male connector - these will then push onto/into the socket on the Powerscope.As I say it has been a while, but if you have any questions I could probably dust off the powerscope on the weekend to re-familiarise myself with it. Especially since my TDS210 is currently waiting a new BNC connector (don't ask) so I need to pull another scope out anyway.....OTOH it has been several months since the OP, so maybe no one is concerned any more anyway

author: siddhant9850
author_rank: Contributor
timestamp: November 05, 2014, 04:33:30 pm
content: finally got it working............yeah

author: RJFreeman
author_rank: Regular Contributor
timestamp: November 06, 2014, 02:40:24 am
content: Nice to see Siddhant.if you wish to use regular CRO probes (although they won't be rated for 3KV etc) then Ebay item number 201094482511 can be modified by cutting off the bayonet shroud/catch on the male connector.Of course while this would mean you can use the Powerscope as a regular CRO (although with differential inputs) it would not have the safety features of the correct probes for the powerscope....eBay item number: 181353324297 is a probe for a power-scope but at $60 + shipping (not sure where you are) you would have to have decided you need it, but if you keep an eye on Ebay the probes do turn up from time to time.Out of vague curiosity what was wrong with it?

author: IconicPCB
author_rank: Super Contributor
timestamp: November 06, 2014, 04:26:11 am
content: I worked at BWD when the concept of the powerscope was developed.The scope initally had four high voltage lower bandwidth capability but it also has ( had) from memory either a 30 MHz or a 40MHz single channel of conventional capability.The project was driven by John Beasley ( the B in BWD).Along with the power electronics capability it had a digital PHASE METER.BWD was bought out by a bunch of accountants who then did what accountants do and in the it was purchased by the production manager anda few other management personel.The name McVan comes from their respective names ( a McPherson and something else which now eludes me ).In the end McVan traded i n BWD, Syncotron and Austenna memorabilia. McVan is still (?) alive in Melbourne

author: yashrk
author_rank: Frequent Contributor
timestamp: November 06, 2014, 04:48:41 am
content: It was around 30-40 USD, it needed some fix which cost us 2-3 dollars.YashRK

author: yashrk
author_rank: Frequent Contributor
timestamp: November 06, 2014, 04:54:15 am
content: @iconicPCB McVan is still there actually I contacted them for repair manual but all they got was it's official user guide.

author: RJFreeman
author_rank: Regular Contributor
timestamp: November 06, 2014, 05:10:10 am
content: I will have to have a scrounge through my Service manual/Data filing cabinet I think I do have a few scraps of schematic for the 881 Powerscope somewhere, pretty sure I had some schematics when I fixed mine (turned out a 12V regulator was faulty) but I would have to move a Burroughs L6000 first....the earlier Powerscope (was it the 880? - I did say 880 on Wikipedia, but then I also see that I mention an 882, which I don't think exists so not sure I can believe myself....) did have limited bandwidth on the higher voltage channels IRC but the 881A or Powerscope mkII goes to either 20Mhz or 30Mhz on the main channels depending on the range you select.BTW for anyone interested I did start writing up a Wikipedia page on BWD - feel free to add or correct:http://en.wikipedia.org/wiki/User:Mosfet_RJF/BWD_Electronics

author: RJFreeman
author_rank: Regular Contributor
timestamp: November 07, 2014, 12:49:57 am
content: OK I have scanned the bits that I have, I fear they are incomplete and are copies of copies (and probably copies of copies of copies), but they are the best I have unfortunately.The schematics look like they have been shrunk from A3 to A4 and then blown up to A3 again at some point in the past but hopefully you can mostly make out what is going on....The largest file size this forum can handle is 1M and these are 2M each, Ebaman seems to be suffering a dummy spit at the moment (or is being stuffed by a firewall here at work) and likewise while BAMA says it is open for uploads I cannot get an FTP connection working so for the time being I have dumped these on Dropbox for the moment until I get home and try uploading from there.....https://www.dropbox.com/s/2v0d3rdbdhotysa/BWD%20881%20part%201.pdf?dl=0https://www.dropbox.com/s/8cs3eanyw5qierh/BWD%20881%20part%202%20schematics.pdf?dl=0

author: RJFreeman
author_rank: Regular Contributor
timestamp: November 07, 2014, 04:33:28 am
content: ... and now Ebaman is back I have uploaded them there also :http://www.ebaman.com/index.php/remository/ELECTRONICS/Test-Equipment/BWD/

author: IconicPCB
author_rank: Super Contributor
timestamp: November 08, 2014, 02:05:20 am
content: I have manuals for BWD509B and BWD830 scope.My 830 was built form scrap pieces, junk bin etc.Hand adjusted for 42MHz bandwidth. A tad above the spec.

author: RJFreeman
author_rank: Regular Contributor
timestamp: November 08, 2014, 02:22:17 am
content: Quote from: IconicPCB on November 08, 2014, 02:05:20 amAh yes, the at one time seemingly ubiquitous 509, I think I might have one somewhere along with a couple of spare CRTes. If it is the one I am thinking of it had hybrid Solid state and valve circuitry.The 830 I am less familiar with, but I have (or did I give it away?) a 539 somewhere and a 521 packed away, but my favourite is the BWD 845, although maybe it just appeals to the Luddite within, to have/use an Analogue storage 'scope....

author: IconicPCB
author_rank: Super Contributor
timestamp: November 08, 2014, 03:55:36 am
content: The 845....I seem to recall there was a contract from RAN to supply some scopes.. Beasley was very busy working up a new scope design for the contract..I think it was an 84x something.The prototypes were made and sent to GAF ( Government Aircraft factory,a place which lives on in memory )to be non destructively, it was hoped, tested on the vibrating platform.The scope survived and was delivered to RAN. It ofcourse could not compete with the Tektronix of the day but it was Australian made.One of engineers at BWD was ex GAF.

author: RJFreeman
author_rank: Regular Contributor
timestamp: November 08, 2014, 06:26:00 am
content: Quote from: IconicPCB on November 08, 2014, 03:55:36 amYes the Tektronix 466 was 100Mhz but the beauty of the BWD 845 even today is no odd ball custom IC's inside, and mostly all bog-standard parts (although the CRT would be un-obtainium today) for a trade off of only going to 30Mhz.But sure you can see why BWD may have struggled to compete without the ability to tap the same level of resources/custom IC fab that Tektronix had available and then when cheaper kit from SE Asia started flooding in....

author: RJFreeman
author_rank: Regular Contributor
timestamp: November 08, 2014, 06:32:31 am
content: But then I guess that was why John (who sounded like he was no fool) would have started looking at Niche products like the Powerscope.

author: AllTheGearNoIdea
author_rank: Unknown
timestamp: September 05, 2017, 09:14:22 pm
content: I was clearing out my stores at work when I found my old powerscope II. Perhaps some TEA sufferers will enjoy a quick look. The fun starts about 18 minutes in. Part two will show the scope in more detail.https://youtu.be/wWGGbHnRqo0Regards Chris

author: Cliff Matthews
author_rank: Unknown
timestamp: September 09, 2017, 01:34:10 pm
content: This is an Australian "Power Scope" in action.FWIW, if this nice instrument were mine I would restore the color on the bezel :-)https://youtu.be/QJXpzKi9t98?t=22s

author: AllTheGearNoIdea
author_rank: Unknown
timestamp: September 09, 2017, 08:32:35 pm
content: Thanks CliffI bet someone on here can probably design a better mains cross detector LOL !I think the bezel is a tribute to those that think a brown bathroom suites is stylish Still the turquoise knobs are a nice touch.Regards Chris

author: Electro Detective
author_rank: Super Contributor
timestamp: September 10, 2017, 12:04:18 am
content: Guys, great info and videoand FWIWwatch out for input 5, the trigger input on the far right.IIRC it is not isolated because the BNC connector case is tied to earth ground on the scope i.e. not differentialEDIT:ALL the input BNC connector cases are tied to earth/ground in the same manner, the differential/isolation magic happens because of the P90 probe wiring which makes no outer ring connectionSo watch out for that if you plan to use different cables, probes and adapters etcSame deal with the rear connectors, I plan to somehow jerry rig cable one day to feed a 4 channel single ended input DSOwithout instigating pre-NYE fireworksThe scope leads came in two types, P90 (1x) and P91 (10x)They sorta look the same, watch out for that otherwise if you mix them the differential measurements may not look like what you expectDoes anyone still repair/service these Powerscopes in Australia?

author: tautech
author_rank: Super Contributor
timestamp: September 10, 2017, 12:47:59 am
content: Quote from: Electro Detective on September 10, 2017, 12:04:18 amThe best selection of BWD manuals that I've seen is from Kevin Chant:http://www.kevinchant.com/bwd.htmlBut there's no powerscope ones there.AFAIK McBride in Melbourne IIRC or is it Adelaide still has some bits and pieces for BWD.

author: Circlotron
author_rank: Super Contributor
timestamp: September 10, 2017, 04:07:10 am
content: Here's me, back in late 1985 (edit -> late 1986) scratching my face and staring at the brand new PowerScope we just got. I was the design engineer and we used to make SCR based soft starters for 3-phase induction motors up to IIRC 1000A per phase. Fun times!

author: AllTheGearNoIdea
author_rank: Unknown
timestamp: September 10, 2017, 06:54:10 am
content: Wow really nice to get some context around using the 881. It's definitely not as smooth a user experience as using equipment from the big boys TEK etc. The push switches are particularly annoying and I'm guessing they could not afford the cost of developing custom switches at the time. I'm not too convinced by the styling with the mix of cream turquoise and brown not exactly a super hero colour scheme. What were they thinking ?I have one of the 10:1 probes they come in a blue pouch all the others are contained in red pouches. The 10:1 only has a single connector lead but has the ground clip so I assume this is not differential and was perhaps designed for channel 5.I don't really like the idea of fused probes either, not that you should be using the scope as a dead tester. The probes are painful to disassemble as you see in part 1.I love the picture above the expression on your face says it all. It reminds me of listening to Jazz. It like music but shit.I wonder how it's performance compares to the new EEV differential adapter ?

author: AllTheGearNoIdea
author_rank: Unknown
timestamp: September 10, 2017, 07:04:35 am
content: Just wondered with all the face scratching if you got your grey beard now given the picture was taken in 85. Great picture thanks for sharingChris

author: tautech
author_rank: Super Contributor
timestamp: September 10, 2017, 07:54:32 am
content: Quote from: AllTheGearNoIdea on September 10, 2017, 06:54:10 amI've only had one BWD scope and all the images I've seen of them indeed they used a different colour scheme to anything else on the market, intentional ? Of course IMHO.QuotePowersopes were quite unique and in some way still are just like Circlotron pointed out with his specialised (for then) usage decades ago.I think a buddy still has one stashed away.....I'll give him a yell to see if he still has it and knowing him he might have the manuals too.

author: Electro Detective
author_rank: Super Contributor
timestamp: September 10, 2017, 10:15:50 am
content: Quote from: tautech on September 10, 2017, 07:54:32 amA different colour scheme and layout etc is a surefire way to be competitive, and NOT get sued for 'inspired' stylingQuote from: tautech on September 10, 2017, 07:54:32 am15 minutes of fame awaits the gent here and any info is appreciatedThese scopes aren't going to fade away easily, well mine isn't,it's the only piece of gear I can confidently 'probe' a suspect or fluctuating circuit containg voltage grunt, and not praytoo loud

author: AllTheGearNoIdea
author_rank: Unknown
timestamp: September 10, 2017, 12:15:50 pm
content: Yes I could do with a manual also. Many thanks Chris

author: Electro Detective
author_rank: Super Contributor
timestamp: September 11, 2017, 06:30:28 am
content: I checked the fuses in my four P90 probes (1x) to ensure they are 100ma fast blow 3AG glass types,and sorted one which wasn't performing consistently, and had the issue pictured,semi-hidden, hard to spot cracked solder jointsRemoved the fuse first, in case I cooked it, then a solder refresh just enough to do the cracked sides only, and good as new.Multimeter reads about 33 to 37 Ohms for any of the 4 probes, which is the 100ma fuse impedance (and a quick way to check rather than disassemble)The P91 probes (10x) are next, best left for another day asap,...perhaps a more fiddly job you need 4 hands (and two brains?) to assemble

author: Electro Detective
author_rank: Super Contributor
timestamp: September 11, 2017, 06:41:30 am
content: Quote from: AllTheGearNoIdea on September 10, 2017, 06:54:10 amI have one of those too, if you unscrew the snapping jaws thingie, the ground clip plastic ring assembly just slides up and out. Give it a slight twist to wake it upThe specs are/should be the same as a regular P91 (10x) without the death croc attached, but please verify for yourselfQuote from: AllTheGearNoIdea on September 10, 2017, 06:54:10 amIt gets easier...after the 8th one

author: tautech
author_rank: Super Contributor
timestamp: September 11, 2017, 08:15:42 am
content: Quote from: Electro Detective on September 10, 2017, 10:15:50 amYep, he actually has three, yes three !880 x 1881 Powerscope 2 x 2Only has the 881 Manual available for scanning.Never scanned a manual before so would need some guidance on the best path to take.I have an inbuilt scanner on a printer that works OK....not networked but can save the scans locally and send them on.What's the best method to accumulate them....into Word and then Save as a PDF ? ?Intended targets to upload manual to are Kevin Chant (mentioned above) and EBAMAN.I can get the manual most any day but ATM I have a job I'm working on for Siglent that must take precedence.

author: Electro Detective
author_rank: Super Contributor
timestamp: September 11, 2017, 08:44:02 am
content: Scan to PDF might be the easiest one step process and WYSIWYG ?Where does one upload to for free, without joining some 'free' tr0jan installing download site ?Quote from: tautech on September 11, 2017, 08:15:42 amMy freshly calibrated FrukeEnvy Meteris reading "OL"Quote from: tautech on September 11, 2017, 08:15:42 amThere's no hurry or obligation, whenever it works for you

author: Moshly
author_rank: Regular Contributor
timestamp: September 11, 2017, 09:30:16 am
content: Previous thread on bwd manuals ->https://www.eevblog.com/forum/testgear/bwd-product-catalogues-(vintage)/This seller on ebay has power scopes listed occasionally >http://stores.ebay.com.au/test-equipment-auctionsBut they never sell because they ask $600 AUD

author: Circlotron
author_rank: Super Contributor
timestamp: September 11, 2017, 09:56:54 pm
content: Quote from: Moshly on September 11, 2017, 09:30:16 amBrand new in 1986 they cost $4200

author: RJFreeman
author_rank: Regular Contributor
timestamp: September 11, 2017, 11:36:56 pm
content: QuoteI either upload to the Boat Anchor Manual Archive:http://bama.edebris.com/manuals/or Ebaman:http://ebaman.com/(which has the dodgy copies of the 881 that I uploaded - please feel free to replace these with better/clearer versions).My approach (which was limited by the lack of flexibility of my scanner - which presumed all the pages were the same size) was to scan the A4 pages as one file, and the schematics (which were usually A3 pages) as the 'schematics' file.You generally do have to sign up to these sites, and to be fair it would be ill advised to set up such a site, and then make it open-slather so anyone could upload whatever they wanted.Having said that I can vouch for both BAMA and Ebaman. My understanding is that BAMA was set up for older manuals (although I have uploaded one or two BWD manuals) while Ebaman is for any manuals, including those for more contemporary equipment.

author: tautech
author_rank: Super Contributor
timestamp: September 12, 2017, 12:31:07 am
content: Quote from: RJFreeman on September 11, 2017, 11:36:56 pmThanks for some scanning insights.My thoughts were to have copies at both sides of the world, hence EBAMAN and Kev's site.I have an A/c at EBAMAN so that's the logical choice for me then I can just email it to Kev and he'll take it from there. (if it's not too big) The other option is to put it in a hidden page on my website and once Kev's got it delete it.I'll check the 881 manual you've uploaded and make some plan from there.

author: tautech
author_rank: Super Contributor
timestamp: September 12, 2017, 12:56:27 am
content: Quote from: RJFreeman on September 11, 2017, 11:36:56 pmThanks again, you may have saved me a big job as those manuals look plenty good enough for those wanting to repair an 881. The two 1.6 Mb files are fine, schematics well clear enough and quite legible.However they are only the schematics (Pt 2) and 881 specs, manual changes, adjustment and alignment portions (Pt 1), do we need more ?ED, I'll email them to you if you don't want to setup an EBAMAN A/c. PM me.

author: Electro Detective
author_rank: Super Contributor
timestamp: September 12, 2017, 01:13:30 am
content: I just realised I had those "dodgy copies of the 881 files"not sure if there's any missing parts, but looking forward to any puzzle completion work guys, this aussie classic workhorse needs preservingI reckon there's a few still kicking aboutforgotten warriors exiled to locked cabinets and storage bunkers, since the DSO and Differential Probe invasion took hold...FWIW once posted I have a mate who 'might'(enter beer and jug smiley)OCR the files at his work, and crossed fingers include Index Table/Chapter and Search/Find capability that you see on most PDFs.Assuming no legal issues to think about,is there anyone that must be consulted first for an 'official ok' ?Quote from: Circlotron on September 11, 2017, 09:56:54 pm$600 isn't too bad for what it is...if there isn't another $3600 to spend on renovations and calibrations once it arrives ((x100 ))

author: Circlotron
author_rank: Super Contributor
timestamp: September 12, 2017, 01:26:34 am
content: And that's 1986 dollars BTW.

author: IconicPCB
author_rank: Super Contributor
timestamp: September 12, 2017, 01:53:07 am
content: BWD gear was never designed with custom or non standard components.The zerocrossover and phase instrument were based on standard CMOS PLL and counters.The vertical amplifiers were typically designed around LM733 and descrete transistors...Vertical attenuators...descrete metal film resistors.In fact i seem to recall vertical gain was not an issue in case of powerscope...

author: Electro Detective
author_rank: Super Contributor
timestamp: September 12, 2017, 02:27:42 am
content: Quote from: Circlotron on September 12, 2017, 01:26:34 am$11,000 today, give or take a slab of beer ?Quote from: IconicPCB on September 12, 2017, 01:53:07 amGood recall, at the 200v per division position armed with a pair of the 10x probes,you can get some serious prodding work done, without too much 'isolation' head scratchingThat said, it still pays to verify everything is working first every time, before snapping away with those stock Big Momma probesand cobbled up DIY adaptersto boldly go where no probe has gone before...

author: RJFreeman
author_rank: Regular Contributor
timestamp: September 12, 2017, 05:28:36 am
content: QuoteFeel free to ask if you want me to grab a measurement from one, I have two 881es, (but no 880)I had one, and got the second one as a 'spares machine' then thought I would have a look at what was wrong with it.....Although my second 881 is missing the back panel.QuoteI wouldn't think so, It's not like BWD exist any more, As a general rule if something is out of print it is fine to copy it and I would be surprised if McVan had printed or sold any in the last decade or so.

author: Electro Detective
author_rank: Super Contributor
timestamp: September 13, 2017, 09:10:04 am
content: Got motivated/curious/suspicious and pulled apart four P91 probes (10x) to see if any issues and no problem, they look well made and sturdy ('robust'?)besides straightening up and re-aligning (bending back and reshaping) a pair of abused alligator snappers from previous ownerand some contact spray lube on the pull apart connectors to get rid of any black scum and tarnish, they will probably provide another 30 years of serviceA heads up to other owners that the P91 (10x) probes do not not have any inline fuses like the P90 (1x) probes have,so don't get too daring thinking a brainf@rt or freaky spike at 10x will only cost you a 100ma glass fuse or two..that isn't there-------------------Also noted that the P90 (1x) probe tips have no connection with their outer plug metal sleeve, therefore fully isolated from any earth/ground points on the powerscopewhereas the P91 (10x) probes read 4.50 megohms from probe tip to plug tip,and 5.50 megohms from plug tip to metal sleeve on the plug, which connects to powerscope earth/ground.

author: Electro Detective
author_rank: Super Contributor
timestamp: September 17, 2017, 02:01:30 am
content: A heads up to 881-11 owners that ALL the input and output BNC connector cases on the Powerscope are tied to earth/ground in the same manner.Two Fluke multimeters can't be wrong.The differential/isolation/no BANGS! magic happens because of the P90 (1x) probe wiring, which makes no outer ring connection at the plugSo watch out for that (if you didn't already know) especially if you plan to use different cables, probes, DIY dividers and adapters etc directly into the scope inputs(best to have the fused P90 probes as the interface in case the DIY situation goes south)i.e. do not assume 'safe', as with any test gear and DUT setupOTOH the P91 (10x) probes do have a relationship with the earth ground ring/sleeve as described in earlier comment, so take that into account alsoHope it's not too confusing... better said than not I reckon

author: tautech
author_rank: Super Contributor
timestamp: September 19, 2017, 08:08:17 pm
content: Grabbed that Powersope manual for my mate last night, it's a later one from McVan and for 881A....is that what you guys have ?One another matter......what are those insulated BNC style push in connectors on the Powerscope probe leads called ?Are they some industry standard or proprietary to BWD ?Bodges that can be used instead ?Sources ?

author: RJFreeman
author_rank: Regular Contributor
timestamp: September 20, 2017, 12:09:52 am
content: QuoteNo, the one I had was a BWD version, from memory there was part of the schematic missing, and the resolution is not that flash (albeit mostly readable).what we have is at:http://www.ebaman.com/index.php/remository/ELECTRONICS/Test-Equipment/BWD/if you want to have a look and decide if you think it is worth going to the effort of rescanning the manual you have.QuoteI have only ever seen them on Powerscopes, so have always thought they were proprietary BWD.Quoteyou can buy BNC to BNC adaptors off eBay* strangely enough (I think they are used to save wear and tear on test equipment).I purchased several of these, stuck them in a vice, and used a hacksaw to cut through the Bayonet shroud and broke it away.that may not make much sense, so I cut as per the attached picture....current listings:eBay item number: 253095219822eBay item number: 140651286327The search I used was : male to female BNC adaptor -RCA -F -UHF -SMA -Banana

author: Electro Detective
author_rank: Super Contributor
timestamp: September 20, 2017, 12:47:23 am
content: Quote from: tautech on September 19, 2017, 08:08:17 pmThe one I have here is an '881 Powerscope 11',the 881A Powerscope 11 may be a later model,afaict they appear identical in form and function in photosThat said, the 881A has a much less brown coloured vibe on the front panel, perhaps the 'A' may indicate 'Aesthetic' model ?RJFreeman beat me to it, a male BNC plug without the locking bayonet outside ringIf you want to use your own leads, probes and custom thingies/DIYs etc to fill up the scope for some multi-channel differential fun,you would need to have a dozen BNC male to female adapters (about $3 each), dremel off the locking bayonet outside ring,and you're in business without having to hack up your current arsenalFWIW I bypassed the dremel and hacksaw business, squashed the locking bayonet 'slightly' in a small vice,rotated a few times and repeated,the ring eventually fatigues and breaks off/shatters cleanly with no damage or marks to the part requiredPatience, good hearing listening for the break sounds, and 'vice intuition' are required to get it right, otherwise you may trash the adapter.Please note the outer ring on the bodge adapters will still be making contact with earth/ground on the scope even though the locking bayonet outside ring has been removed.The BWD P90 (1x) probe leads are truly/physically isolated with no connection to the plug barrel at all, and have a 100ma fast blow 3AG glass fuse (30 to 37 ohms) in case of a differential probing snafuSince we're inBodge Territory...if you cut or file off the two small rear metal posts on RJFreemans adapter example above, you can use the same adapters to plug BWD probes into other other gear,a bodge twofer

author: tautech
author_rank: Super Contributor
timestamp: September 20, 2017, 01:00:07 am
content: Quote from: RJFreeman on September 20, 2017, 12:09:52 amYep, I've got those you uploaded to Ebaman, my thoughts were to add only the Operation section to complement what you've done already.This manual's front cover is marked McVan Instruments and has a cut out to see BWD881A PowerscopetmOperation & Owner manual inside on the first page.Then a page or two later in the Table of contents at the foot of the page: Copyright 1990 McVan Instruments Ver1/Mar90So 28 years later is it safe to copy it and put it online ?QuoteYes, they seem as hard as rocking horse shite to find.QuoteWhat I did notice last night when looking at the BWD probe connector is how fine and pointed the centre pin of these connectors are and as I've seen the standard for the BNC centre pin is not consistent over the industry, so I'd be thinking very carefully about using any old BNC adaptor for fear of damaging those in the unit.Unfounded fears ?My buddy is pretty anal about this sort of stuff after decades with test gear and sometimes unexplained damage to BNC's and intermittent connects.He's got a few probes without ends and failing coax at the plug that he'd replace in a flash if the push in BNC's were available.

author: Electro Detective
author_rank: Super Contributor
timestamp: September 20, 2017, 01:11:45 am
content: I noticed the larger pin on some standard BNC adapters but it hasn't been an issue, they slide in easily,and no drama when using the BWD plugs afterwards, I just assume the scope sockets spring back on the retaining nylonWill play around asap and get back on that, maybe I got lucky.. I'm not a big fan of 'luck'unless it's Tattslottoplus post some pics of a slight CRT trace rotation adjustment issue I am having, and maybe get some suggestions or 'leave it be'Update:spoke to one of the local Jaycar gurus about this, and he's confident there are two sizes of BNC pins and sockets that he's aware of in their stock/systemI'm going to have to do it the hard wayand measure everything up to work out what suits what, to have everything fit properly.

author: woodchips
author_rank: Frequent Contributor
timestamp: September 20, 2017, 07:47:36 pm
content: Thanks to evryone posting this PowerScope info. I bought one in an auction years ago, worked, but with 400V input never actually used it, time to drag it out.I would point out that the Fluke 123 DSO also uses 1:1 BNC probes that work to 600V. One of the strange things with it, the bandwidth really needed better than 1.5m of coax stuck in front of it, but might be suitable replacements.

author: IconicPCB
author_rank: Super Contributor
timestamp: September 20, 2017, 10:13:38 pm
content: Electrodetective,Make sure you do not mix 75 ohm and 50 ohm BNC connectors, externaly they are identical, internally they are different and mating the two will damage one of them... depending on their respective genders...needles to say.

author: RJFreeman
author_rank: Regular Contributor
timestamp: September 21, 2017, 01:35:46 am
content: QuoteThat was my initial thought when I saw your post yesterday, but while I do know that the hole for terminating the cable in the back of the pin is smaller on a 75 ohm BNC than a 50 Ohm, I was not aware of any difference in the diameter of the pin itself.Doing further investigation I find that IEC 169-8 did specify that you should be able to plug 50 ohm BNC connectors into 75 ohm and vice versa without causing damage, while the MIL standard that covers BNC connectors (MIL-STD-348) specifies a centre pin between 1.32 and 1.37 mm diameter regardless of Impedance.However I also find references to BNC connectors having different diameter pins, depending on impedance, prior to IEC 169-8 in the 1970es and 1960es.Not to mention that the connector we are talking about is not technically a BNC as such, but rather seems to be a propriety connector based on the BNC, so therefore may, or may not necessarily conform to any BNC specification....Having said that, when I first got my 881 I did not have the right probes for it, so used a modified BNC to BNC adaptor as per my earlier post. Later on I managed to get a set of the original probes for it and have not had any issues subsequently using them with the 881, although it would also be fair to say that it is not my most used oscilloscope.

author: Electro Detective
author_rank: Super Contributor
timestamp: September 21, 2017, 10:15:15 pm
content: Gents, if the BNC standards, pin sizing, and'variable manufacturing OS standards'fiasco doesn't drive you totally nuts, imagine yesterdays adventure I had with 15 tarnished aged BNC sockets to contend with, on a banged up 881 service/restorationi.e. random intermittent connection blissregardless of whether adapters or proper BWD probes usedand this is after I got the Time Base back on track, Chop function working, rear outputs going, re-soldered cracked joints, tightened and pushed in some intermittent terminals and a general clean up.These old school multichannel scopes are a lot of intensive yakka, especially if abused, so with 10kv-ish potentials tread carefully if you're in thereIn the end I carefully directed some Servisol contact lube into the BNC-ish sockets and massaged them with a perfect fit round wound guitar string scrap, to get the 30 year old black tar out.Amazingly all but one works perfectly. That one that had an issue on the board as well > fixedIf you are going to make up adapters or fit new plugs on the BWD probes, you better take a working 'BWD Friendly' pin and socket example/sample with you to a parts store/s and spend some time matching up.Beware they might all look and labelled the same in the parts boxes at the store, but in most cases they are not. A mixture of new and old stock, different batches,Wun Hung Lo vs Tu Hung Lo factory originsetc...That said, if the scope sockets are tarnished and over expanded to begin with,stop at the chemist too, and ask for extra strong headache pillsFWIW I'll try and get some connector p0rn going asap.. when/if I find my elusive dusty macro/close up kit