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Discussion Starter · #1 ·
My hvps started arcing about a month ago and silicone fixed it. It started arcing again today. I I started digging into the gray stuff and noticed a bunch of black hard stuff that I think is charred rubber. Should I keep on digging and replace any of this char I can find, or is this actually a better insulator than Silicone? I fear my hvps's days are truly numbered.I'd say I have dug about a centimeter and there is still a bunch of this stuff. The hole is located about 2/3 up and 3/4 to the right (looking from the back)
 

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Discussion Starter · #2 ·
So is this "char" burnt insulator or a perfectly fine insulator? I would like to fill the hole with silicone tonight so that I can use the pj later this week. I know that this hvps is probably about to die, but I would like to make it to summer when I do an overhaul (probably retube) until I replace/ send off this hvps.
 

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Any charring is a conductor. The carbvon deposits conduct HV excelently!

So start scraping.


I'll be scrapping some MArquee chassis within the next 2-3 weeks so I should have some spare supplies...


Curt
 

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Discussion Starter · #4 ·
Thanks Curt. My 9000 uses 34kv tubes, so I hope you get some good later hvps's to sell.
 

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I am so stupid. I expected 1cm thick silicone to dry in 24hrs. It is stinking wet after 20hrs. I suppose I should layer it in 1/4cm layers? The tube advertises curing in 24hrs, but how long should I wait between layers? 12hrs?


Edit:

I was thinking that the charring was caused by a leaking cap generating excessive heat. I have heard that these high voltage caps are very pricey, but how expensive are they? The rest of the hvps seems to be in good working order, so replacing the entire unit just seems like a waste since this hobby is all about raising the dead.
 

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Michael,


Some silicones won't cure if there are other chemicals present. The silicone rubber mold makers run from things like masking tape which is a notetorious fouler of silicone setting-up.


Also, It's best if you use an electronic grade silicone. The stinky stuff has acetic acid that can corrode parts (when curing) an that leads to other problems.


There may not be a bad part at all, just arc generated carbon. Curt's right - you have to get rid of all of the black stuff, then replace the air gap you created with a good insulator. Sometimes, I'll use sheet mica as a barrier before applying the silicone.


If the circuit board has an arc path, it must be completely removed. Sometimes traces must be removed and replaced with wire.



Regards,



Barry
 

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Discussion Starter · #8 ·
where do I get some electronics grade silicone? I didn't see anything like that at Home Depot, and I doubt that someone there would know where to look if it even was there. So should I just cut the entire cube of gray stuff off or just in the problematic area? Seems like it would require a bunch of silicone to get it sealed again. If I had to solder, what grade/ type solder should I use?


Thanks for all the help
 
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