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Tek 475 Front Panel Ground Point


 

I have two scopes of my father's, one 475 and one 2213. The ground point on the front panel of the 2213 is just a banana plug socket, but on the 475 the ground point is a knurled metal post (looks like nickel). This always puzzled me because the post could turn, but didn't seem to unscrew, and it is much too big to attach a ground clip from a probe, or do much of anything else with. Well, today I solved part of the mystery of this odd ground point: it's a separate banana plug with screw-down terminal!

I went on the web looking for any images of a Tek 475 with this banana plug in the ground port, and I can't find a single one. I don't know why this never occurred to me before now, except that the ground point is rarely mentioned in Tek documentation (it doesn't even get it's own numbered label in the 475 Operators Manual), and the knurled post doesn't photograph very noticeably, no more so than an empty banana plug socket. I suspect that my father added this (possibly generic) banana plug to his scope as some convenience of his own (not sure what that would be, though: I had to use pliers to loosen the knurled nut, and the revealed contact faces, post and hole show no obvious signs of use), but he didn't add a similar piece to his 2213, so I'm at a loss for a sensible explanation.

I've tried to search Amazon for a similar part (assuming that it's a generic piece of kit) with little success, but I may not be using the right search terms.

Does anybody know if Tek shipped such an accessory as part of the stock 475?


Colin Herbert
 

I have two 475As and neither have anything like you describe. They both have an banana-socket earth-point just to the left of the bottom left screw holding the CRT bezel in place. However, I have a couple of 7000-series plugins (7A13 & 7A22) which have earthed metal binding-posts with banana-plug sockets, where the knurled "nut" will unscrew completely and expose a hole drilled laterally across the metal post. These two plug-ins are capable of differential measurement between two inputs and I would guess that this earth-point is necessary for differential measurements. Perhaps your father was attempting to do differential measurements using the two channels on the 475 with one channel switched to "invert". If you look up info on differential measurements and how to make the connections, it might be a bit clearer.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jeff Dutky
Sent: 05 November 2020 04:25
To: TekScopes@groups.io
Subject: [TekScopes] Tek 475 Front Panel Ground Point

I have two scopes of my father's, one 475 and one 2213. The ground point on the front panel of the 2213 is just a banana plug socket, but on the 475 the ground point is a knurled metal post (looks like nickel). This always puzzled me because the post could turn, but didn't seem to unscrew, and it is much too big to attach a ground clip from a probe, or do much of anything else with. Well, today I solved part of the mystery of this odd ground point: it's a separate banana plug with screw-down terminal!

I went on the web looking for any images of a Tek 475 with this banana plug in the ground port, and I can't find a single one. I don't know why this never occurred to me before now, except that the ground point is rarely mentioned in Tek documentation (it doesn't even get it's own numbered label in the 475 Operators Manual), and the knurled post doesn't photograph very noticeably, no more so than an empty banana plug socket. I suspect that my father added this (possibly generic) banana plug to his scope as some convenience of his own (not sure what that would be, though: I had to use pliers to loosen the knurled nut, and the revealed contact faces, post and hole show no obvious signs of use), but he didn't add a similar piece to his 2213, so I'm at a loss for a sensible explanation.

I've tried to search Amazon for a similar part (assuming that it's a generic piece of kit) with little success, but I may not be using the right search terms.

Does anybody know if Tek shipped such an accessory as part of the stock 475?


Daveolla
 

At 10:25 PM 11/04/2020, you wrote:
I have two scopes of my father's, one 475 and one 2213. The ground point on the front panel of the 2213 is just a banana plug socket, but on the 475 the ground point is a knurled metal post (looks like nickel). This always puzzled me because the post could turn, but didn't seem to unscrew, and it is much too big to attach a ground clip from a probe, or do much of anything else with. Well, today I solved part of the mystery of this odd ground point: it's a separate banana plug with screw-down terminal!
lar part (assuming that it's a generic piece of kit) with little success, but I may not be using the right search terms.

Does anybody know if Tek shipped such an accessory as part of the stock 475?
Yup,I (banana plug with small knurled end) have one and it is listed in the Tek 468 Scope manual as; "adapter, Ground Wire .......134-0016-01"
So you finally decided to give the post a pull ......................sorry, I had been meaning to suggest that to you:(

Dave




 

Dave, Colin,

Thanks for the replies. I also found (and lost the auction for) a 475A on eBay that showed the ground wire adapter in a bag of "accessories" so it was clear that this was original equipment. Differential measurements seems a very likely suggestion considering that my father was a service engineer for a manufacturer of mass analysis and associated equipment when he got and used this scope.


Colin Herbert
 

I have just undertaken a voyage of discovery amongst my various bits and pieces and not only do I have one of these, but it is shown in my 475A Service Manual as "Plug, Tip: W/Binding Post" in the "Accessories" section. Oddly enough, though, I can't (at present) find it in my 468 Manual, which come in two parts, nor in the Common Design Parts catalogues. I suppose that with the 475 that was your father's, there is one of these in the earth-point socket that I mentioned that both of my 475As have.

Now if only I could find the bits that I was actually looking for.....

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jeff Dutky
Sent: 14 November 2020 19:18
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek 475 Front Panel Ground Point

Dave, Colin,

Thanks for the replies. I also found (and lost the auction for) a 475A on eBay that showed the ground wire adapter in a bag of "accessories" so it was clear that this was original equipment. Differential measurements seems a very likely suggestion considering that my father was a service engineer for a manufacturer of mass analysis and associated equipment when he got and used this scope.


Michael W. Lynch
 

My 465B, 475 and 475A all have the grounding post in the ground socket. I also have a couple of 7000 series plug ins that have them as well. I guess I was just lucky to end up with so many?

--
Michael Lynch
Dardanelle, AR