Elastomer strips for Tektronix LA probes

[CBrandin]

I recently had zebra elastomer strips made for my P6860 logic analyzer probes. I've benefited greatly from members of this forum, so in the interest of giving back I'm offering to mail a bunch of them (both the long and short ones) to anybody who wants some.

These are a little different than the originals in that they use carbon as the conductor instead of wires - but they appear to work perfectly.  I don't know how many times they can be removed and reattached, but I haven't managed to wear any of them out so far.

Specifics are:

pitch - .05mm
length - 7mm (short) and 11mm (long)
core width - 0.5mm
conductor material - carbon
color - black
width - 1mm
height - 1.5mm
non-conductive material (insulation and sides) - silicone rubber

I have hundreds of them so any reasonable request will be accommodated - I'll even pay postage, as long as it's US domestic rate postage, or close to it.

Chris

[tautech]

Welcome to the forum.

That's a real nice gesture. 

Not that I want or need any but some pics will help.

[CBrandin]

There's not much to see, they are just tiny black rectangles. They fit into the elastomer holders, both the thin and the thick versions. You can see a diagram at this web site (these are the YS type):

http://www.angeliy.com/cp/html/?64.html

[nctnico]

Very interesting! The hoarder in me is definitely awakened but I have to think about it.

[TerraHertz]

Wooo! Thank you!
I have 5 Tek P6860 probes, that I got cheaply because 2 of them are missing most of the elastomer strips. And one of the heads is missing the elastomer strip holder. I can't image how people do this.

I hadn't yet dared inquire re the price of replacements from Tek, mainly because I'm certain I couldn't afford them.
The probes were still a good deal because one of them had a Mictor connector attached, and the seller didn't know what it was.

When you say the carbon ones work, did you test the upper frequency limit? I'd expect it wouldn't be as good as the metal filled ones. But no big deal, as long as one is aware of it.

Did you get them cut to the two different lengths, or long strips to cut as needed?
In any case, can I have enough to make say 10 probe sets?


I'm in Australia, but use a US reshipper address you can post to:
 Guy Dunphy
 3503 Jack Northrop Ave
 Ste J8637
 Hawthorne, CA 90250
 USA

Pic is of the probes and strips, for people who wondered.

Edit:
Annnd, since I have the probes out, and I've been meaning to disassemble one since it has a problem with the cable insulation being cut too short at the head...  Two more pics added.

In the disassembly shot, you can see the two detents on the inner body, that lock the outer case. To release, slide a plastic shim like in the pic, in from the rear. Shim at least 0.5mm thick. Pull the outer cover off towards the front, while pulling on the mounting screw heads, not the cable.

Looks like this one was badly manufactured, with the insulation stripped off too far. Does not appear to be a result of cable strain.

2nd edit, to add another pic of how to disassemble the P6860 probe head. Note I've depressed the label into the two hidden detent openings to show where they are. Also that the labels on each side are different shapes. The detents are on the 'concave-top' label side.

Btw, if you only have one probe, don't forget to mark which way the two cables go into the mounting before taking it apart. There's no markings on the two substrates to show which is which. Fortunately for me I have more than one probe, so could work it out, having not realized I should mark them first.

[nctnico]

AFAIK the strips cost several tens of dollars from Tektronix so it isn't a ridiculous amount.

[lukier]

I too recently bought 4 P6860 probes, fortunately most of them had elastomer strips, but I found on eBay 18 elastomer holder assemblies + 2 mictor adapters for decent price so when it comes to elastomers I'm OK.

However, none of the probes had nut bar holders. I suppose people use press fit / soldered in-pcb nuts and throw away the nut bars. I would prefer nut bars. Does anyone know a source for these or Tek price? If it is ridiculous I might think about 3D printing something with hot pressed nuts embedded in the ABS, maybe it'll work.

[TerraHertz]

AFAIK the strips cost several tens of dollars from Tektronix so it isn't a ridiculous amount.

I didn't say the price would be ridiculous, I said I wouldn't be able to afford it. I'm exceptionally poor, due to exceptionally unusual circumstances.

That said, "several tens of dollars" for presumably one probe set of 4 tiny strips that probably cost a tenth of a cent each, _is_ ridiculous.

[CBrandin]

TeraHertz,

I'll get them in the mail today.

I can't think of any reason these won't support full bandwidth.  The resistance is less than 1/2 OHM and capacitance is negligible.  These are commonly used for display interfaces that run in the tens of GHz. These are pre-cut to the two lengths, so you won't have to do anything to use them. The only thing about carbon conductors is that you may not be able to reuse them as often as the originals, so I'll send you extras.

These cost me $0.005 each - pretty good price, wouldn't you say? That means I can send you 100 of them for the price of a stamp.

Chris

[CBrandin]

lukier,

Are you connecting to landing pads that already exist, or are you creating them yourself?  I built some test rigs where I made the mounting holes smaller (the width of the mounting screw instead of the width of the extruded part of the nut bar) and used 1/4" threaded nylon standoffs on the other side to hold the connector in - so far it has worked fine.  Simply creating a nut bar out of plastic won't work very well as the plastic used for 3D printing is too soft and won't prevent warping - the Tektronix nut bars are metal inside. I looked long and hard for nut bars without any luck. Frankly, I haven't found warping to be an issue unless the PC board is unusually thin.

Chris

[CBrandin]

By the way - here is the Tektronix patent on the probes: http://www.freepatentsonline.com/6781391.pdf

I think they are using this technology on several different probes - not just the P6860

Chris

[lukier]

Are you connecting to landing pads that already exist, or are you creating them yourself?  I built some test rigs where I made the mounting holes smaller (the width of the mounting screw instead of the width of the extruded part of the nut bar) and used 1/4" threaded nylon standoffs on the other side to hold the connector in - so far it has worked fine.  Simply creating a nut bar out of plastic won't work very well as the plastic used for 3D printing is too soft and won't prevent warping - the Tektronix nut bars are metal inside. I looked long and hard for nut bars without any luck. Frankly, I haven't found warping to be an issue unless the PC board is unusually thin.

My own landing pads, using the Eagle footprint found here in some other thread. I also want to make an adapter PCB from the landing pads to 0.1" pins for the Tektronix leadsets.

I like your idea with nylon standoffs, easy to buy and should be OK for normal PCBs. For the adapter PCB I'll probably go with press-in/soldered nuts to save some space and make it more permanent.

[CBrandin]

I built myself some boards to connect to the lead sets as well. They work fine, however bandwidth is considerably reduced. I also built myself some smaller boards that simply bring out the landing pads to pads along the edge that I can solder to.  The pads on the edge match up nicely as long as you put the ground pads along the top and bottom (allows for bigger signal pads).  Its a two sided board with all traces on top and a ground plane on the bottom. It's easy to make such a board where the trace lengths are all exactly the same (which is more difficult with the lead set interface board). This scheme has some advantages, although you end up soldering wires to what you want to connect to.  First, as I mentioned before, it's easier to make all the traces the same length.  Second, when soldering directly you don't have to use series resistors (as long as wires connecting to the target are short enough).  The Tektronix lead sets have a 150 OHM resistor in series with the leads, which reduces noise, but also reduces bandwidth considerably. If you layout several of these little boards the overall size still comes out to the minimum size for most board fabricators which brings down the price to the point where you don't have to reuse them (i.e they come out cheap enough so as to be expendable and you can just leave them connected to the target).

Chris

[CBrandin]

By the way - my wife Alice Brandin is mailing the strips - so don't throw the letter away because the return address is from her rather than me.

[nctnico]

As long as she didn't include a picture it will be OK. Just in case my wife opens the mail 

[CBrandin]

On another subject...  I recently acquired a Tektronix TLA714 for really cheap because the display had lines on it (a common failure, I would guess).  The display panel is a NEC "NL 8060AC26-11". It's very easy to install and costs about $90 from several Chinese sources.

Chris

[TerraHertz]

For improvised nut bars, what's wrong with just a piece of aluminium or brass, tapping the hole threads, then put a layer (or several) of kapton or ordinary electrical tape on the PCB side for insulation?
If you don't have the tapping tools, make it of brass and solder on the appropriate nuts. (Use sacrificial countersunk head stainless steel screws to center the nuts on the holes while soldering. S. Steel so no chance of soldering in the screw too. Same two screws can be used multiple times.)

My TLA 721 I got cheap because the seller didn't have the Windows startup password, so could not run the system tests. Turned out the password was the Enter key, ie no password. 

TeraHertz,

I'll get them in the mail today.

Thanks!

I can't think of any reason these won't support full bandwidth.  The resistance is less than 1/2 OHM and capacitance is negligible.  These are commonly used for display interfaces that run in the tens of GHz. These are pre-cut to the two lengths, so you won't have to do anything to use them. The only thing about carbon conductors is that you may not be able to reuse them as often as the originals, so I'll send you extras.

These cost me $0.005 each - pretty good price, wouldn't you say? That means I can send you 100 of them for the price of a stamp.

Excellent.
Which raises the question of why Tektronix couldn't be bothered to do this, to make these consumables for their probes available in bulk for very low cost.

It's also interesting to know you were able to do a custom bulk order of elastomer strips for low cost. Something to bear in mind when thinking up new products in future. How was the process? Any tips and gotchas to relate?

[nctnico]

My TLA 721 I got cheap because the seller didn't have the Windows startup password, so could not run the system tests. Turned out the password was the Enter key, ie no password. 

That is neat. AFAIK you can update the TLA721 with a TLA7016 master module (basically a VXI to ethernet box and you run the software on your regular PC). My TLA715 was cheap because the hard drive wouldn't work but that turned out to be a problem with the removable hard drive bay (worn contacts). An internal SSD (mSata on an mSata to 44pin adapter) works just fine. I looked at the TLA721 as well but shipping to the NL is insanely expensive for such a heavy unit.

[CBrandin]

I got the strips from this company (they custom made them to my specifications):

CMAI INTERNATIONAL LIMITED
B558, Nanfang Mingzhu Building, Donghuanyi Road,
Longhua New District, Shenzhen, China 518109.
Tel: 86-755-28146223
Fax: 86-755-28146329
E-Mail: sales@cmaisilicone.com
Website: www.cmaisilicone.com

They were really great to work with and delivered within days.  Some other companies wanted $1 each for the parts.  When I researched this I discovered that there is a huge range in pricing depending on the company, so shopping around is a good idea.  Outfits like www.globalssources.com can arrange for several companies to bid automatically. Sometimes there is a minimum amount you have to spend or a minimum number of parts you have to buy. I ended up buying 10,000 parts for $50 plus $40 for shipping via DHL. There were no tooling charges or anything like that. I didn't have to buy so many parts but I figured I should spend at least as much on the product as the shipping - so I decided to get a bunch made and give them away.

[jaranguren]

Hi,

I am interested. Do you have elastomer strips still available?

Thanks!

[CBrandin]

Hi,

Sorry, I haven't been on for awhile.  I certainly can send you some strips.  What is your address?  You can message me if you like.

Chris

[RomDump]

Hi,

Sorry, I haven't been on for awhile.  I certainly can send you some strips.  What is your address?  You can message me if you like.

Chris

Do you still mail out strips?