Shortening USB leads ????

[Skipper Billy]

I am trying to create a setup whereby there is only one wire required between the scope and obsy - a single 12v DC power lead.

I am very nearly there but I am a bit OCD about cables and I have made a small 12v distribution box with cables to the 5 items requiring 12v all made to exactly the correct length.

The USB cables are more of a struggle as I can find 0.5 metre and 1 metre but nothing in between. (The Intel NUC is mounted on the scope)

So my question is - is there any good reason not to shorten a USB cable ??

I am a dab hand with a soldering iron and heat shrink so the practical side isn't an issue - I would have the joints staggered somewhere in the middle of the cable.

Would the lack of screening be an issue around the joint ???

[Dr_Ju_ju]

What flavour of USB, 2.0 3.0 ?? They use differing cores\screenings etc...  If you feel you'll gain from it, go ahead....

[Davey-T]

You could buy new plugs and re-end them.

Dave

[Skipper Billy]

21 minutes ago, Dr_Ju_ju said:

What flavour of USB, 2.0 3.0 ?? They use differing cores\screenings etc...  If you feel you'll gain from it, go ahead....

USB 2 - Type A to Type B (Printer cable) its the one for the camera that I am struggling with - needs to be long enough not to inhibit the focuser movement but no more.

[symmetal]

USB2 cables are fairly easy to do. Rather than make a join in the middle of the cable it's easier to just cut to length and solder a new plug or socket on the end. I bought some free USB2 plugs and sockets from RS for this purpose.

USB3 is a lot more tricky. You can't buy the free connectors so for a short USB3 right-angle cable in my imaging box I had to make a small adaptor PCB to a surface mount plug and solder to that. There are three screens in a USB3 cable, two of which are joined together at the connectors and a third screen which must be kept separate. So you have 10 connections in all. The 4 USB3 data signal paths need to be kept to the same length to avoid signal timing errors causing data skewing. 

Alan

[Skipper Billy]

7 minutes ago, Davey-T said:

You could buy new plugs and re-end them.

Dave

I didnt know that was possible - sounds like a great solution.

Question is how ! (Scurries off to Google it!)

[Skipper Billy]

Just now, symmetal said:

USB2 cables are fairly easy to do. Rather than make a join in the middle of the cable it's easier to just cut to length and solder a new plug or socket on the end. I bought some free USB2 plugs and sockets from RS for this purpose.

USB3 is a lot more tricky. You can't buy the free connectors so for a short USB3 right-angle cable in my imaging box I had to make a small adaptor PCB to a surface mount plug and solder to that. There are three screens in a USB3 cable, two of which are joined together at the connectors and a third screen which must be kept separate. So you have 10 connections in all. The 4 USB3 data signal paths need to be kept to the same length to avoid signal timing errors causing data skewing. 

Alan

Thanks Alan - thankfully the problem one is a USB 2 cable - type A to type B - printer cable.

I will have a scout round on RS Comp.

That sounds like a great solution. Thank you!

[Guest]

0.75m USB 2 A to B:

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=USB+2.0+A+to+B+0.75m&_sacat=0

Fill yer boots

[symmetal]

On the RS site search for ASSMANN USB connectors you need to buy the connector covers separately for the type A and B now. When I bought them they were all together. Here's the new stock numbers

674-2268 type a connector £0.58 

113-5984 type a cover  £0.33

674-2270 type b connector £0.48

113-7151 type b cover £0.33

VAT to be added 

Alan

Edit added part numbers as Oddsocks posted. 

[Oddsocks]

Also, Farnell carry standard lengths (amongst others) 508,750,800,900 type a to type b.

https://uk.farnell.com/w/c/cable-wire-cable-assemblies/cable-assemblies/usb-lightning-cables?connector-a=usb-type-a-plug&connector-b=usb-type-b-plug&cable-length-metric=508mm|750mm|800mm|820mm|900mm

I do make up my own USB cables if needed for something special, parts from RS components, but, you do need a special crimping tool to make the screen clamp connection properly, you "can" squash the cable clamp closed with pliers but the result is never that secure or pretty and if you are too aggressive you can puncture the data cables inside the shielding.

If you want to try the RS USB2 plugs the stock numbers are below, you need both the plug and the hood.

Type A solder termination USB2 plug, ASSMANN WSW RS stock number 674-2268

Type A hood-cover for USB2 plug, ASSMANN WSW RS stock number 674-2264

(Just pipped to the post by Alan....?)

[Skipper Billy]

18 minutes ago, Sland said:

0.75m USB 2 A to B:

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=USB+2.0+A+to+B+0.75m&_sacat=0

Fill yer boots

Cheers Sland

[Skipper Billy]

@Oddsocks and @symmetal

Cheers - parts ordered - OCD fed - great result.

Thanks very much.

David (aka Skipper Billy)

[symmetal]

You mentioned screening in your first post Skipper Billy. For USB2 it's not critical on short lengths. Some 30cm USB2 adaptor leads I bought and cut up they didn't even use screened cable, just plain 4 core cable. They also didn't conform to the USB wiring colour code as I found out when I plugged it in and shorted the 5V to ground.  Black was 5V, Red was data, Yellow was ground. I always 'buzz' the cables I make up before using them and don't rely on the colours being right any more.

Alan

[Skipper Billy]

1 hour ago, symmetal said:

You mentioned screening in your first post Skipper Billy. For USB2 it's not critical on short lengths. Some 30cm USB2 adaptor leads I bought and cut up they didn't even use screened cable, just plain 4 core cable. They also didn't conform to the USB wiring colour code as I found out when I plugged it in and shorted the 5V to ground.  Black was 5V, Red was data, Yellow was ground. I always 'buzz' the cables I make up before using them and don't rely on the colours being right any more.

Alan

Cheers Alan - I will buzz them to make sure once they are made up before plugging anything - thanks for the heads up.