Wonky HDMI cable - Page 1
Forum section: electronics / projects

author: Renate
author_rank: Super Contributor
timestamp: June 24, 2021, 03:37:29 pm
content: I was having a problem with an HDMI cable that would drop out if you manipulated the connector a certain way.As I have zero tolerance for this kind of stuff, I whipped out the dykes and cut the connector off.(Sometimes I even use the massacred cables as breakouts.)With all these tiny differential cables like USB-C, HDMI, Display Port, I wondered how they can economically make them.With a bit of chopping and hacking I could see.It's a good solution since the biggest problem with multicables is getting the individual lengths all the same.In days gone by, I made up TV-81 connectors for broadcast camera cables:https://www.tvcameramuseum.org/cameracables/biw/biw-tv81-1.html

author: AndersJ
author_rank: Frequent Contributor
timestamp: June 24, 2021, 04:18:59 pm
content: I have emission problems from HDMI-DVI cables, well over 1 GHz.It seems they have bad (no?) shielding.Can you see how good your cable shield is?

author: Renate
author_rank: Super Contributor
timestamp: June 24, 2021, 04:55:16 pm
content: Actually the shielding and construction was pretty good.The bare ends of the wire as they came out of the IDC had a strip of Kapton tape over the connector body.Then the connector was molded the first time.The a pretty solid one piece metal shell like a funnel was pushed down the cable onto the connector and crimped.It was soldered to the metal of the connector.Two little pieces of copper tape covered the cracks.Then the whole thing was molded a second time.

author: actuallyjaseg
author_rank: Contributor
timestamp: June 25, 2021, 03:30:54 pm
content: That solderless construction technique is at the same time amazing as it is concerningI recently had issues with a brand new Displayport cable: the thing was rated for Displayport 1.4 30 Gbit/s operation, but could barely handle DP 1.1 10 GBit operation. I bought it intentionally overspec'ed because I needed a DP 1.2 20 Gbit cable and I wanted to avoid getting a marginal cable. The thing wasn't cheap, and when I took apart the connectors they were actually soldered, so I guess they must have saved cost with the cable in betwee instead.I think cable vendors can just get away with a lot since most customers may not use the cable at the top end of its spec and never notice.

author: Renate
author_rank: Super Contributor
timestamp: June 25, 2021, 06:01:39 pm
content: Well, if you've every tried to terminate a bulky cable where the individual leads were 15 mm or so longyou can appreciate the benefit of just stripping the jacket 50 mm or so, threading the conductors through the connector bodyand having the (presumably patented and expensive) crimper cut off the excess wire length.Of course, some knuckleheads will simply strip the cable 50 mm anyway and have 25 mm of un-jacketed cable outside the shell.

author: bugrobotics
author_rank: Regular Contributor
timestamp: June 25, 2021, 08:16:05 pm
content: I tested around 30 HDMI cables for a project a few years ago. HDMI shielding termination is all over the place manufacturer to manufacturer. Only 3 cables tested satisfactory for the project (emissions sensitive environment). Tearing the cables apart after testing provided some explanation into the performance issues. Shield termination varied from a lousy 30+ AWG wire over 25mm from the connector to full 360° termination. Price corresponded pretty tightly with the quality of shielding termination. Not that anyone was asking but LCOM was the winner for price and performance.

author: tooki
author_rank: Super Contributor
timestamp: June 26, 2021, 03:02:24 pm
content: Quote from: actuallyjaseg on June 25, 2021, 03:30:54 pmWhy concerning? Solder-free connections are probably used for the majority of wires in existence. Crimped connectors are everywhere. IDC (insulation displacement) connectors are also everywhere: if you have a copper phone or DSL connection, chances are that nearly every connection it goes through is wired this way. The ethernet cabling in the walls at home and in the office are all terminated with IDC. So are the connectors on the patch cords.Why? Assembly speed and reliability. Soldered connections, especially to wires that move, are rather unreliable.