What is PowerScope

[RJFreeman]

any info is appreciated 

Feel 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.

Assuming no legal issues to think about,
is there anyone that must be consulted first for an 'official ok' ? 

I 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.

[Electro Detective]

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 owner 
and 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 service   

A 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 powerscope

whereas 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.

[Electro Detective]

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 plug

So 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 setup


OTOH the P91 (10x) probes do have a relationship with the earth ground ring/sleeve as described in earlier comment, so take that into account also


Hope it's not too confusing... better said than not I reckon   

[tautech]

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 ?

[RJFreeman]

it's a later one from McVan and for 881A....is that what you guys have ?

No, 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.

Are they some industry standard or proprietary to BWD ?

I have only ever seen them on Powerscopes, so have always thought they were proprietary BWD.

Bodges that can be used instead ?

you 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:   253095219822
eBay item number:  140651286327

The search I used was :    male to female BNC adaptor -RCA -F -UHF -SMA -Banana

[Electro Detective]

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 ?

The 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 photos

That 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 ring

If 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 arsenal 

FWIW 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 required

Patience, 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 snafu   


Since we're in Bodge 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     

[tautech]

it's a later one from McVan and for 881A....is that what you guys have ?

No, 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.

Yep, 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 Powerscope^tm Operation & 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/Mar90

So 28 years later is it safe to copy it and put it online ? 

Are they some industry standard or proprietary to BWD ?

I have only ever seen them on Powerscopes, so have always thought they were proprietary BWD.

Yes, they seem as hard as rocking horse shite to find. 

Bodges that can be used instead ?

you 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:   253095219822
eBay item number:  140651286327

The search I used was :    male to female BNC adaptor -RCA -F -UHF -SMA -Banana

What 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. 

[Electro Detective]

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 nylon   

Will play around asap and get back on that, maybe I got lucky.. I'm not a big fan of 'luck' unless it's Tattslotto

plus 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/system

I'm going to have to do it the hard way    and measure everything up to work out what suits what, to have everything fit properly.

[woodchips]

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.

[IconicPCB]

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.

[RJFreeman]

he's confident there are two sizes of BNC pins and sockets

That 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.

[Electro Detective]

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/restoration

i.e. random intermittent connection bliss      regardless of whether adapters or proper BWD probes used 

and 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 there   

In 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 > fixed   


If 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 origins etc...

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 pills 


FWIW I'll try and get some connector p0rn going asap.. when/if I find my elusive dusty macro/close up kit