SE30 CRT anode cap removal reveals red sticky material

[Alex]

Hello

I am doing a complete cleanup and visual inspection before I go through repairing the logic board. Anyway, I noticed that once I removed the anode cap a red sticky material was found on the anode cap and the anode aperture.

I wonder what this material is, I imagine it is there to act as a glue to keep the cap in place, or at least help it stay in place.

I am wondering if anyone has more info and whether this material is critical if so, I have wiped some off when it occurred to me that it is likely needed.

I would truly appreciate any information.



Kind regards

—Alex Santos

 

[Reasons.]

I don't have any specific information, but I think it's just the plastic of the cap decaying. I've cleaned off that goop from all the machines I've disassembled and they've continued to work just fine.

 

[Alex]

Thanks Reasons. I will continue to investigate this and report back if I do or don't find anything. If anyone else has more information please don't hesitate to contribute any knowledge or theories.

 

[Bolle]

I had a few compacts with this goo as well. Most do not have it (yet?) though.

It seems to be just as Reasons says: The rubber of the suction cup dissolves itself into this gooey crap just like the bumpers you find in hard drives or the feets on most 68k PowerBooks.

 

[techknight]

Nope, this is a form of dielectric grease that keeps the moisture out of the anode cap AND serve as a barrier adding resistance in between anode and ground, its there to prevent arcing. 

 

[Johnnya101]

Just as Tech said, this is the glue type stuff to seal it.

DO NOT REMOVE IT! If you do and don't replace it you may have issues! You may get along fine but its there for a reason. The clear caps I have encountered have the same stuff, like the red ones. The cap you can clean, but not the glue.

 

[Bolle]

This is strange as actually most of the compacts I had seen from the inside yet did not have this flue/goo/whatever in place.

I totally see it would make sense to have some kind of grease in place right there but never thought of Apple actually using any because most Macs I came around to put my hands on did not have it in place.

 

[Alex]

Found this so far: https://electronics.stackexchange.com/questions/144846/what-is-the-red-orange-coating-underneath-a-crt-anode-suction-cup-and-is-it-imp?rq=1

Although the above is the closest I could find, the questions on that forum appears to be unsettled at the time of my posting the link. There does however appear to be consensus that the material was used to prevent potential arcing that might occur under some circumstances. The original poster appears to have settled the issue with this purchase: http://www.mgchemicals.com/products/insulating-coatings/super-corona-dope-4226

Difficult to find specific information on this topic I'm afraid. 

 

[Alex]

Just as Tech said, this is the glue type stuff to seal it.

DO NOT REMOVE IT! If you do and don't replace it you may have issues! You may get along fine but its there for a reason. The clear caps I have encountered have the same stuff, like the red ones. The cap you can clean, but not the glue.

Indeed, the anode caps, once cleaned showed no evidence that it had dissolved over time. It felt very sturdy in fact. I will have to source replacement material. Do you know the name of this material or is the Corona dope I mentioned in a previous entry in this thread recommended?

 

[techknight]

to be honest, I dont think the voltages on a 9" B&W CRT are high enough to be concerned with sealant. were talking only 10KV or so here. 

 

[Alex]

Not to beat this to death but, I would like to add one more link if I may, hope it's still there, if not try the waybackmachine (for all tomorrow's parties).

https://www.electronicspoint.com/threads/compound-for-anode-cups.51605/

In fact search that forum for "dielectric grease CRT" or google it. Turns out you can by this grease in the automative section of your local shops. Basically this grease is designed to seal the connection from humidity and which prevents arching. This is what I understood.

Thanks for everyone's input, it really helped me and I hope it serves others as well. 

 

[Scott Baret]

It's very common, although the amount of the grease seems to vary from Mac to Mac. I've probably removed about 30-40 of these and sometimes you get a greasier one. I actually dealt with two today...one had almost nothing on it. The other had so much that even the top of it was greasy.

There is no difference between Clinton and Samsung CRTs in terms of the difference of how much is on these or the variation thereof.

 

[Alex]

Hi

I had cleaned the anode cap prior to posting but I thought I should take the opportunity to show the cap as it has no degradation, just some circular spots that I can't account for but it is clean now.

By the way, I heard that silicone grease can be applied, any truth to that? Hopefully silicone grease is not a conductor cause that would be bad, also would silicone grease erode or otherwise degrade the cap over time?

My display happens to be a Clinton Taiwan Corp display, just an FYI.





Best

—Alex Santos

 

[Carboy7]

My Classic II had some sticky stuff on the anode cap too, and was on the top and the bottom of the cap.

I don't know about rubbing it off, but it probably won't do anything.

 

[Alex]

Nope, this is a form of dielectric grease that keeps the moisture out of the anode cap AND serve as a barrier adding resistance in between anode and ground, its there to prevent arcing. 

Hi Techknight, I did some research and yes you are right, it is dielectric grease to prevent arching and seals the anode from exposure to foreign materials that could be conductive and cause other issues like sparking which would result in frequent and annoying clicking (sparking) noises.

Do you know if the variety of dielectric grease used for spark plugs and other electrical car parts appropriate for the this particular application?

 

[techknight]

You, definitely are beating this to death.... 

DONT worry about it! 

 

[unity]

Do you know if the variety of dielectric grease used for spark plugs and other electrical car parts appropriate for the this particular application?

I really hope you don't put the grease on spark plugs, its for the boot. And as for connectors, same. Should never touch the contacts.

 

[techknight]

I use dielectric grease on our product line, mainly to stop the connections from corroding when they are installed in florida or anywhere with salt air. All of our interconnects are ribbon cable, and it works great for that. 

 

[JDW]

For those interested, especially you, @Alex, I just posted a detailed reply on this very topic to "Tom2112Tom" in the Comments section under my newly uploaded FAN VIDEO here.