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-   -   Green goo in coax (https://www.vintage-radio.net/forum/showthread.php?t=183241)

The Philpott 27th Aug 2021 2:41 pm

Green goo in coax
 
You're all aware of the green goo interaction between old PVC and copper..I saw it in coax for the first time today. I suspect that digital signals are more vulnerable to bad connections caused by this sort of thing, leading to blocking, dropouts, pixellation, nerve shattering digital screeches etc. Hopefully resolving this will solve the issues i've been trying to ignore for months- only permanent cure in this case though, is to rip out all the cable and replace. Oh Joy..
Dave

Trevor 27th Aug 2021 3:30 pm

Re: Green goo in coax
 
while I was in the trade I was called to a faulty Rotel tuner on opening it up i could see that the input socket was corroded on checking the installation I noted that the coax feeder cable when opened up was full of water ! My conclusion an open connection box at the arial end had allowed rain water in .This along with the height difference created enough pressure for the rain water to enter the tuner and create the corrosion
Trev

G6Tanuki 27th Aug 2021 4:20 pm

Re: Green goo in coax
 
I've seen the green goo in some coax; it's usually caused by the plasticiser degrading and reacting with the copper. Added moisture helps the process along.

Black corrosion on the braid is another nof-unusual thing; again, water ingress is usually to blame.

In either case the coax is scrap.

SiriusHardware 27th Aug 2021 4:22 pm

Re: Green goo in coax
 
I saw a Freesat receiver completely ruined in the same way, satellite coax makes a great drainpipe if the connection at the LNB is not waterproofed with self-amalgamating tape. I've seen some dish installations where the bare 'F' connector was just left to fend for itself.

Guest 27th Aug 2021 5:01 pm

Re: Green goo in coax
 
A generous slavering of Vaseline also helps, and I mean generous to the point of very messy.

The Philpott 27th Aug 2021 8:27 pm

Re: Green goo in coax
 
Post No.3- Rightly or wrongly, I associate 'black rot' with exposure to salty air. I've known it travel more than 12 inches up inside automotive wiring.
Dave

Top Cap 27th Aug 2021 10:24 pm

Re: Green goo in coax
 
Quote:

Originally Posted by Trevor (Post 1401855)
while I was in the trade I was called to a faulty Rotel tuner on opening it up i could see that the input socket was corroded on checking the installation I noted that the coax feeder cable when opened up was full of water ! My conclusion an open connection box at the aerial end had allowed rain water in .This along with the height difference created enough pressure for the rain water to enter the tuner and create the corrosion
Trev

When in the trade many many many years ago, my boss and I went to fix a TV suffering from poor picture. The coax was full of water as could be seen by the water dripping from the aerial plug. When the customer asked how could that be, my boss said "You've been watching too much Thames Television" :D. It's appreciated youngsters may not get that joke. :)


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