[NTLUG:Discuss] Local solution ... Re: OT USB standards

[Fred James]

agoats at compuserve.com wrote:
> You're all suffering from mechanical tolerances to the connectors. If 
> you go and get the USB 2.0 standards at
>
> http://sdphca.ucsd.edu/Lab_Equip_Manuals/usb_20.pdf‎
>
> Chapter 6 has the mechanical dimensions, and what is happening is a 
> variety of :
> 1 maximum tolerance male to minimum tolerance female = tight fit
> 2 minimum tolerance male to maximum tolerance female = loose fit
> 3 minimum tolerance male length and maximum tolerance length (depth) 
> female = not so good electrical contact
>
> and so on. Worst case design says it should always work, but as you 
> get some wear, the performance goes down.
>
> I'm suffering some of the same issues with SATA connectors: they lose 
> contact with the drive.
>
> Alvin
>
> On 02/14/2014 08:53 PM, Christopher Cox wrote:
>> On 02/13/2014 05:50 PM, Fred James wrote:
>>> OT: USB standards
>>> In particular, the physical dimensions of the connections
>>> Why are the connections not all the same size ... even within one 
>>> brand?
>>> In trying to plug a USB stick into a computer USB port I find some 
>>> loose, some
>>> tight, and some just too big to fit at all.
>>> What's up with that?  Is this like other "industry standards" ... 
>>> not standard
>>> at all?
>> The ones that are the worst are the plastic sheathed ones.  I guess 
>> they have to
>> make it a bit thicker.  Oh... I'm talking about USB sticks of course.
>>
>> I have an USB SDHC adapter that fits really tight in my Cubox... oh.. 
>> and again,
>> I'm talking about a USB adapter and a USB port.... in case there was any
>> question about that.
Local solution ...
(a) insert short A-A M-F USB cable into computer and leave it there
(b) insert USB device (such as memory stick) into short cable listed in 'a'
(c) when the wear is too much, replace cable listed in 'a'
... used to do that with DB25 connections when the application called 
for a lot of switching (manual connect/disconnect) in an application 
where an A/B switch was inappropriate ... long story.

Thanks for the input
Regards
Fred James