Tektronix type 553 powercord. (SOLVED) - Page 1
Forum section: electronics / repair

author: atos
author_rank: Contributor
timestamp: April 22, 2015, 01:59:58 pm
content: Hi,got my hands on an old Tektronix T-533 oscilloscope which is missing a power cord. I rather avoid going through the hassle taking it apart to convert it to a normal C13/C14 plug since it's basically located beneath everything and I rather not considering the amount of tubes this thing contains, besides I'd like preserve original as much as possible. Not that I think things like this will every increase in value unless we have like a major sunstorm hitting earth blowing all ICs to hell.Connector appears to be a NEMA-5-15 US-type, but I'm kind of puzzled since it's reversed sexes and the female plugs I've found on eBay the earth is not perfectly round and rated to 115VAC I suppose that has to do with tins making a proper connection.I guess it's not really a repair but more like a modification to make it usable, so this might be in the wrong section. If it is please feel free to move it, still new around here.EDIT:http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2188545_-1seems to be just what I need. Lol should have abstained from posting just a few more minutes.

author: TimFox
author_rank: Super Contributor
timestamp: April 22, 2015, 06:04:42 pm
content: The Jameco cable has a three-pin "IEC"-style male plug at the other end: is that what you want here?The NEMA end of the cable probably won't fit into the circular hole on the Tektronix panel. When faced with similar connections on Tektronix and General Radio gear, I have taken a standard 3-pin NEMA-style extension cord, with the strange shape outline on the female end (as shown in the Jameco pic) and whittled the vinyl to fit the circular hole, using a Stanley utility knife.

author: atos
author_rank: Contributor
timestamp: April 22, 2015, 06:27:22 pm
content: Yeah, I have an abundance of those!More than a bit perplexed as to why it has this type of connector though, since it's rated @ 198-235VAC. It's the first time I see something like it myself.Ah, so it wont be a perfect fit? I thought that was only my imagination. But yeah, if it wont fit I'd use the same trick as you describe. Also gave some thought to using hotglue and make a mold, but I felt it would'nt be adequate. :p

author: Paul Moir
author_rank: Frequent Contributor
timestamp: April 23, 2015, 03:48:21 am
content: Are you in North America? If not I think I understand.I think the round vs U shape is just to accommodate the possibility of a stamped metal ground pin on the male connector, which is necessarily U shaped. These are common on replacement plugs (ie, not moulded) for some reason. I remember some old female receptacles from when the 3 prong plugs first came out had a circular ground socket, so the U shaped socket may have been added later. Either way they're compatible with round ground pins.I wonder if a standard replacement extension cord socket would fit? Could you measure the diameter of the socket hole? I would be happy to send one.

author: atos
author_rank: Contributor
timestamp: April 23, 2015, 07:20:30 am
content: Oh no, I'm in Sweden. Seems reasonable. But still I'm used to males docking into females, not females docking into males, it's bizarre!Anyhow, thanks for confirming and your offer, would be great if I could cancel my Mouser order. Diameter is roughly ~0.866inch or ~2.2cm.

author: TimFox
author_rank: Super Contributor
timestamp: April 23, 2015, 05:07:12 pm
content: The Tektronix panel has a male connector because it is a load. The mating connector is female, since it can be "hot" and must not have male pins for safety.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: April 24, 2015, 01:57:49 am
content: Oh, that's quite a bit smaller than I was picturing: the type I was thinking of won't fit. I'll hunt around a bit more and see what I can find, but I have my doubts.Sorry about that!

author: TimFox
author_rank: Super Contributor
timestamp: April 24, 2015, 12:52:20 pm
content: If I remember correctly, the original Tektronix power cable had a rigid plastic shell at the female end to fit that small hole. However, I have had good results with the "scrimshaw" approach on a normal American extension cord (vinyl insulation). However, these extension cords are only rated for 125 V.

author: SeanB
author_rank: Super Contributor
timestamp: April 24, 2015, 05:36:15 pm
content: The double insulated 3 core types will handle 240VAC with no problem. The only issue is the single insulated 2 wire types, which are not really rated for mains use.

author: kolbep
author_rank: Frequent Contributor
timestamp: April 24, 2015, 05:50:39 pm
content: Cant you use Female Push On Terminals (like they use on Alarm battery connection) for the Live and neutral terminal connections, and a bullet ferrule (terminal) to connect to the earth pin.You just take whatever cable you have (with your standard plugtop on it), cut off the other end, and crimp on the ferrules. Then once you have pushed it onto the terminals in the socket on the device, fill the socket with Sugru or Silicon, to make a safe moulded plug.??

author: atos
author_rank: Contributor
timestamp: April 28, 2015, 07:06:53 am
content: Yeah I was thinking about doing the mold approach. Have plenty of PCL for the connector and Sugru for the insulation part it would undoubtedly be the cheapest solution. But I'd prefer something that gets me as close to original as possible.Been in contact with Mouser and it looks as though I got a match.