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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 27th Aug 2021, 2:41 pm   #1
The Philpott
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Default 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
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Old 27th Aug 2021, 3:30 pm   #2
Trevor
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Default 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
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Old 27th Aug 2021, 4:20 pm   #3
G6Tanuki
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Default 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.
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Old 27th Aug 2021, 4:22 pm   #4
SiriusHardware
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Default 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.
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Old 27th Aug 2021, 5:01 pm   #5
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Default Re: Green goo in coax

A generous slavering of Vaseline also helps, and I mean generous to the point of very messy.
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Old 27th Aug 2021, 8:27 pm   #6
The Philpott
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Default 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
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Old 27th Aug 2021, 10:24 pm   #7
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Default Re: Green goo in coax

Quote:
Originally Posted by Trevor View Post
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" . It's appreciated youngsters may not get that joke.
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