Preventing HV flashover on socket pins

[M Gregg]

only overpriced contact cleaner that doesn't actually work on pots.


...

You need to use Servisol 10....it actually works on bad pots..contact cleaner may or may not work and it removes all lubrication and the pot goes bad quickly as the track breaks up and goes to powder..Its available on Ebay I saw it the other day...OK you do have to check that any solvents don't damage the plastic in the pots, however I have had very very good results..It does leave a very slight lube and it lasts so the pot stays clean.. The only thing I would add is some pots have a mechanicaly resistive grease in the shaft bearing to give luxury feel to rotation and servisol will remove this if you just soak the pot with it..

BTW WD40 isn't pot cleaner and it makes the situation worse..

I would'nt use standard paint to insulate you wont be able to solder through it...If I didn't care about soldering through it I would use the insulating varnish that is used on transformers....however any repairs would be a pain..

Regards
M. Gregg

 

[M Gregg]

Now here is a thought,

Does anyone know what to put back on the shaft of a pot to get the mechanical resistive feel back after a clean..I guess you could put it on the shaft on the outside of the pot and let it creep in.(capillary effect) It can only be some Kind of grease..it feels a bit like tar to the touch but dosen't set...

This is off topic so I have started another thread...

Regards
M. Gregg

 

[trobbins]

Some guitar amps used spaghetti, or a short section of the outer insulation sleeve from mains wiring, to slip over the socket pin/cable for the anodes of PP amps. I even saw them glued in place on one amp.

Maybe nowadays it would be better to use a smidge of engineering silicone rubber to make a continuous 'solid insulation' barrier to assist with creepage as well as clearance.

 

[Wavebourn]

great contributions guys. good pointers!

What brandnames does silicon-organic compound come under?

Forget about it, it was meant for military equipment. Silicon-organic compund protects for ages. As Tom said, you will probably want to repair it some day.

 

[nazaroo]

Some guitar amps used spaghetti, or a short section of the outer insulation sleeve from mains wiring, to slip over the socket pin/cable for the anodes of PP amps. I even saw them glued in place on one amp.

Maybe nowadays it would be better to use a smidge of engineering silicone rubber to make a continuous 'solid insulation' barrier to assist with creepage as well as clearance.

I've used 'heat-shrink' or 'spagetti' on my power octal pins with good results. If you don't heat it too tight it can slide off easily for repairs.

I haven't tried the combination of heat-shrink and HV insulating lacquer though, along with significantly higher voltages, and wondered about other people's experience with this. I'm thinking along the lines of 700 to 1300 volts Anode (1625s or 813s).

I resolved long ago to mount parts on a separate turret or PCB for easy repair, rather than right on sockets. I know this goes against the rule for stopper-resistors, but I can manage that exception especially for input stages, without cluttering up all the sockets needlessly.

Repairs and mods are so much easier when parts are clearly laid out on a turret board.

I'm thinking that only Octal sockets (designed for lower voltages) are really susceptable to tracking and shorts (excepting the 5-pin and 7-pin sockets for 807s and 1625s). As I recall, the sockets for 813s and bigger tubes have a good spread and don't crowd the leads.


I love the silicon rubber they sell in hardware stores, for bathroom repairs. Its also easy to peel off for repair and replacement.

But I have a serious concern here, because (and you can tell from the smell) acetic acid (vinegar) is used as a 'setter' for the drying/hardening process. As the moisture evaporates, it is true that the acetic acid becomes 'inert', but obviously adding moisture/humidity reactivates it somewhat...

Acid corrodes metals rapidly....

any thoughts?

 

[Wavebourn]

Silicones are different. GE makes and sells as well some "electric" silicones that don't smell.

Speaking of trackings and shorts, only 6L6 and it's clones (except 807) have such a problem, because designers from the beginning put anode and filament pns (2 and 3) close to each other.