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TM5xx extenders
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I've just ordered a set on eBay from John Nery, currently awaiting delivery. These are in kit form so some soldering will be required. He makes custom boards to order using a CNC milling process. I have no affiliation, just passing on the information.
He also included the following note if you want to contact him directly: "In the future please feel free to contact me directly by this e-mail address (WA1ESO@...) for any item you may need and receive a discounted price." |
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Hey Peter,
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I've bought some risers from John for various HP gear. Note that when milling PCBs, it's hard to avoid tears on the edge of the traces, and worst case these can bridge between adjacent traces. It's easy enough to run some kind of scraping implement down the slot between the traces, and it's good insurance against these shorts. Siggi On Tue, Mar 5, 2019 at 2:37 AM Peter Mulvey <peter.mulvey@...> wrote:
I've just ordered a set on eBay from John Nery, currently awaiting |
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I can confirm that Dan's extenders are great. The look totally professional and are based on a ribbon-cable extender, so they are flexible. They have handles to aid plugging in and removal and extra features such as leds to indicate the presence of 25VAC A, 25VAC B, +26VDC, -26VDC, 17.5VAC and +11.5VDC, test points to check voltages and jumpers to be able to monitor power line current or apply external power. Although they can come assembled or kits, Dan will do the SMD soldering for you. I bought two and I'm happy with them.
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Colin. -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of dnmeeks Sent: 05 March 2019 13:07 To: [email protected] Subject: Re: [TekScopes] TM5xx extenders Hello Bill - I saw your message about extenders. I need to see how many parts I have, but I am pretty sure I have everything. I'll check today some time and let you know. Do you want one extender or two (for double-wides)? Dan |
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A word of caution about these extender kits. I have seen these postings on e-bay from time to time and noticed that these kits use a simple circuit board whose edges are either sheared or more likely, routed with a tungsten carbide cutter. Mating the edge that plugs into the mainframe connector will likely damage it on the first insertion. The edge card connectors in the mainframe are plated with hard gold, to a thickness of 100 or 250 micro inches, depending on the vendor. This is a relatively thin plating for a connector that sees a lot of cycles. To be honest, the mainframe connectors used by Tek were not a good choice for this application. They were intended for use in semi-permanent applications, where the only cycling would be board replacement during servicing ¨C not a plug-in where they may see hundreds of cycles in normal life. The vendor¡¯s data sheet for the connectors stated that there design life is only 25 mating cycles. Note that exceeding this cycle count does not necessarily mean the connector would fail, but rather the specifications for contact resistance would not necessarily be met after 25 cycles.
Tek mitigated this short life by treating the male mating fingers on the edge of the plug in. If you look closely at any TM500/5000 plug-in, 5000 series scope plug-in and the Tek made extender cables, you will note several things. First, the fingers themselves are gold plated with 100 micro inches of hard gold over a nickel plate. Copper and nickel are much harder that hard gold and will deform it when mated. More important, the mating edge is treated in two manners. First, it is chamfered to a 45 degree angle with a carbide router bit by the board fabricator. This is essential to prevent the exposed glass fibers from the board edge from scraping the gold off the connector. Again, a single mating with an epoxy glass circuit board into one of these connectors can remove considerable amount of the gold plating from the connector, rendering if venerable to corrosion in high humidity environments. While the chamfering reduces the likelihood of glass scraping the connector when mating, the step where the circuit board foil trace mates would still scrape when it mates. Tek prevented this by ¡°rolling¡± the chamfered edge of the circuit board. The finished board after plating is ran through a pair of conical rollers that actually smashes the circuit board which reduces the thickness of the plated board fingers, allowing them to partially engage into the connector before beginning to deflect the spring function of the contacts. Thus, there is no edge scraping on the connector during the mating process. The board edge engages before it begins to force the contacts open. Users who buy these extender kits can do some of these steps to improve them to prevent connector damage. Using a file, it is possible to put a chamfer on the mating edge. A short length of steel rod can be used as a roller to manually squeeze the connector edge. The only thing the user cannot do easily is add the gold plating, but the contribution of plating is minor compared to the problems of mating a rough exposed epoxy glass board into the mainframe connector. |
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Ditter,
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To which extender kits do you refer? DaveD On 3/11/2019 7:22 PM, ditter2 via Groups.Io wrote:
A word of caution about these extender kits. I have seen these postings on e-bay from time to time and noticed that these kits use a simple circuit board whose edges are either sheared or more likely, routed with a tungsten carbide cutter. Mating the edge that plugs into the mainframe connector will likely damage it on the first insertion. The edge card connectors in the mainframe are plated with hard gold, to a thickness of 100 or 250 micro inches, depending on the vendor. This is a relatively thin plating for a connector that sees a lot of cycles. To be honest, the mainframe connectors used by Tek were not a good choice for this application. They were intended for use in semi-permanent applications, where the only cycling would be board replacement during servicing ¨C not a plug-in where they may see hundreds of cycles in normal life. The vendor¡¯s data sheet for the connectors stated that there design life is only 25 mating cycles. Note that exceeding this cycle count does not necessarily mean the connector would fail, but rather the specifications for contact resistance would not necessarily be met after 25 cycles. |
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Really good info - Thanks - I was about to make up one of those kits
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of ditter2 via Groups.Io Sent: Monday, March 11, 2019 6:23 PM To: [email protected] Subject: Re: [TekScopes] TM5xx extenders A word of caution about these extender kits. I have seen these postings on e-bay from time to time and noticed that these kits use a simple circuit board whose edges are either sheared or more likely, routed with a tungsten carbide cutter. Mating the edge that plugs into the mainframe connector will likely damage it on the first insertion. The edge card connectors in the mainframe are plated with hard gold, to a thickness of 100 or 250 micro inches, depending on the vendor. This is a relatively thin plating for a connector that sees a lot of cycles. To be honest, the mainframe connectors used by Tek were not a good choice for this application. They were intended for use in semi-permanent applications, where the only cycling would be board replacement during servicing ¨C not a plug-in where they may see hundreds of cycles in normal life. The vendor¡¯s data sheet for the connectors stated that there design life is only 25 mating cycles. Note that exceeding this cycle count does not necessarily mean the connector would fail, but rather the specifications for contact resistance would not necessarily be met after 25 cycles. Tek mitigated this short life by treating the male mating fingers on the edge of the plug in. If you look closely at any TM500/5000 plug-in, 5000 series scope plug-in and the Tek made extender cables, you will note several things. First, the fingers themselves are gold plated with 100 micro inches of hard gold over a nickel plate. Copper and nickel are much harder that hard gold and will deform it when mated. More important, the mating edge is treated in two manners. First, it is chamfered to a 45 degree angle with a carbide router bit by the board fabricator. This is essential to prevent the exposed glass fibers from the board edge from scraping the gold off the connector. Again, a single mating with an epoxy glass circuit board into one of these connectors can remove considerable amount of the gold plating from the connector, rendering if venerable to corrosion in high humidity environments. While the chamfering reduces the likelihood of glass scraping the connector when mating, the step where the circuit board foil trace mates would still scrape when it mates. Tek prevented this by ¡°rolling¡± the chamfered edge of the circuit board. The finished board after plating is ran through a pair of conical rollers that actually smashes the circuit board which reduces the thickness of the plated board fingers, allowing them to partially engage into the connector before beginning to deflect the spring function of the contacts. Thus, there is no edge scraping on the connector during the mating process. The board edge engages before it begins to force the contacts open. Users who buy these extender kits can do some of these steps to improve them to prevent connector damage. Using a file, it is possible to put a chamfer on the mating edge. A short length of steel rod can be used as a roller to manually squeeze the connector edge. The only thing the user cannot do easily is add the gold plating, but the contribution of plating is minor compared to the problems of mating a rough exposed epoxy glass board into the mainframe connector. |
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I have just made up a few TM500 prototyping boards from JLCPCB, who added chamfered edges to the card edge fingers, but (based on ditter2's post of two years ago) it looks like I will need to do the "rolling" on the fingers. Does anybody know how much force is required to do this, and what kind of setup I would need?
I can do some minor fabrication with a drill press, but anything more is beyond my current skill or equipment. -- Jeff Dutky |
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The term "rolling" is mentioned several replies earlier (in a post by ditter2 on 11 March 2019) it says the following:
While the chamfering reduces the likelihood of glass scraping the connector when mating,Now that I've read it again it sounds like this might be able to be done by hand applying a small amount of force to a steel bar angled from a point of contact with a flat surface and the point of contact with the edge of the connector fingers being "rolled". I will have to examine some of the my TM500 plug-ins to see if I can measure the difference in thickness achieved by the rolling process. I can't detect any difference with my unaided eye or by touch, but a set of calipers or micrometer may be able to measure it. -- Jeff Dutky |
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Ke-Fong Line wrote:
No problem, I entirely missed the post as well when I was doing research for building my own TM500 prototyping boards a few months ago. Oddly, now that I have had the chance to closely examine a couple of my TM500 plug-ins I do not see any evidence of chamfering on the card edge fingers. I only see a wide chamfer on the key slots between contacts #6 and #7, and contacts #17 and #18. The board itself ends with no apparent chamfer at all along the long edge. The boards that I had made, and the after-market extender that I bought on eBay, both have a 45 degree bevel ground along the long edge of the card edge connector. I wonder if this was a feature of the 5000-series or 7000-series scope interfaces, or if it may have been a feature added to the TM5000 interface. The most that I can see (with a loupe) is what appears to be a very narrow (maybe 0.1 mm wide, at most) wrapping of the gold card edge plating over the corner of the card edge fingers. If this is indeed a thing (and not just a trick of the light) it could obviously be achieved by pressing on the corner of the PCB where the card edge contacts come to an end. I have yet to try it, but I don't imagine it will take much force at all. -- Jeff Dutky |
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I have now examined several 7000-series plug-ins as well, and they do not appear to be beveled either, nor do they show obvious signed of being "rolled". I'm not saying that this was not done, just that it's not obvious to casual inspection (or inspection with a 30X loupe).
Again, I have not actually measured anything with calipers or micrometer, but everything I've looked at looks like an unmodified PCB edge. -- Jeff Dutky |
bill K7WXW
Peter Mulvey
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