stupid defect in p6015 high voltage probe - Page 1
Forum section: electronics / testgear

author: coppercone2
author_rank: Super Contributor
timestamp: March 19, 2019, 02:59:06 am
content: I have one of the freon filled tektronix HV probes. It has a very irritating defect, I think I can make it look nice with a bit of very fine sanding and using car compound and polish on it.The problem is the main connector on the tip of the probe is a screw that is embedded in the acrylic or whatever plastic cone tip/dielectric tank.The area between the conductive pin and the clear plastic became a big foggy/spotty. I can polish the exterior but the interior looks like it has a skin infection. Can this be fixed safely, perhaps by dripping acetone in there with a tiny needle? Or some kind of really thin super glue or super glue dissolved in something really thin?I would like to know before I end up sourcing freon for this or trying to fuck with it to accept silicone oil in its span.Never mind, it looks like you can unscrew the entire tip so long you have a nut driver to remove it and I guess you can even polish the inside but i dunno if thats recommended ?

author: coppercone2
author_rank: Super Contributor
timestamp: March 19, 2019, 03:05:41 am
content: Is it OK to vapor polish this thing with acetone vapor from the inside? I am kind of scared to use abrasives....

author: threephase
author_rank: Regular Contributor
timestamp: March 19, 2019, 07:48:24 am
content: The tip looks like a completely moulded section to me so I doubt you will be able to carry out any internal cleaning of it.You would need to know if the materials are acetone resistant, if they aren't you will probably cause irreparable damage to the unit.Considering the voltage that this probe can go up to, dismantling and attempting repairs may not be a good idea unless you have the specific knowledge to do so.The gas used in this was Freon 114 which is now a banned substance so unless you are very lucky, getting hold of some will not be easy.

author: KrudyZ
author_rank: Frequent Contributor
timestamp: March 19, 2019, 12:18:48 pm
content: Have you looked at the data sheet for the probe?If so, have you tested the 100 MOhm resistor inside the probe body?If not, then what makes you think something is wrong with your probe?You don't actually have to disassemble anything to do that.WRT the Freon, you only need it if you want to run this probe over 13 kV.

author: TurboTom
author_rank: Super Contributor
timestamp: March 19, 2019, 12:57:06 pm
content: The gap between the tip conductor and the acrylic body is filled with resin. On my probe it looks even more spotty and also took a yellowish hue. I'm not sure if it's possible to remove the threaded insert safely without causing collateral damage.Since I got my P6015 for comparably little money, yet without any of the freon left, I tried to figure out alternatives to the insulation gas and currently use butane to fill it. This isn't ideal but at normal room temperature develops high enough pressure to provide the required insulation strength. Since butane vapor will displace the air inside the cavity before closing up the probe, there's no risk of combustion inside. The only (real) disadvantage is that the probe must not be used to its full specs at temperatures lower than 10C. A slight annoyance is that the red gas level indicator ring won't float on the butane...

author: coppercone2
author_rank: Super Contributor
timestamp: March 19, 2019, 04:20:52 pm
content: I am not using butane in 40kv equipment that sounds like it could go horrendously wrong. Like so so wrong. Thats firefly reaver level repair/hacking!!!I want to disassemble it but the problem is all my tools i keep greased and polished. The nut drivers have chrome polish protect and pliers have teflon infused lubricant.I think i will take one of my long needle nose pliers which has multisection pin joints and heat it red hot to drive out the oil so i can have clean tools go i there (after cooling). I will grip the screw thread with lead in a handvise and attempt to twist it.I will measure the 100meg on a eletrometer against a 20meg standard. And 1gigaohm and other 100megaohmI dont want machine oil in there. You can also get the freon, i found something last year but at those prices i want it looking nice when its done.i am very good at finding weird chemicalsThen im gonna go in with a magnified boroscope and scan the entire surface for particles (periscope attachment on usb microscope)

author: coppercone2
author_rank: Super Contributor
timestamp: March 19, 2019, 04:27:17 pm
content: Man you can leave it hooked up to hv equipment, forget about it have a gasket crack have a spark and end up with a flamethrower or possibly a rocket (doubtful)

author: coppercone2
author_rank: Super Contributor
timestamp: March 19, 2019, 04:35:00 pm
content: I think the pin has bad adhesion to the probe. I will be cautious

author: TurboTom
author_rank: Super Contributor
timestamp: March 19, 2019, 05:01:20 pm
content: It's funny how much some individuals get afraid when dealing with combustible gases. The flammability range of butane / air mixture is 1.6%-8.4% of butane percentage in air by volume. Of course, one has to be careful while filling the probe but once the butane is in, there's virtually no chance to keep >90% of air above the liquid in the probe even if you try to close the cap as fast as possible -- the vaporizing butane will simply push out the lighter air above it.Vice-versa, even if the probe develops a leak, as long as there's liquid butane visible inside, air won't be able to flow inside against the gas pressure. And I won't use a probe without at least a little bit of liquid visible inside. A tiny leak (like a leaky seal) wouldn't cause enough gas to escape to pose any danger of combustion externally. I'm the only one using this probe and I'm aware of the possible dangers when opening / refilling it and I'm prepared to take the (tiny) risk.Others may decide differently for themselves and that's okay but I consider working on high voltage circuitry to cause a higher risk than using the P6015 filled with butane.