HV tracking across flexible PCB strips

[Jules Richardson]

On 05/11/2015 01:01 PM, tony duell wrote:
>>
>> Question is, once it's all thoroughly dry, what would be the most
>> appropriate way of re-sealing everything? Would silicone sealant perhaps do
>> the job (dispensing with the top layer of the sandwich entirely and just
>> coating the bottom layer/traces) and stand up to the HV OK?  Or some form
>> of glue?
>
> Firslty, some silicone sealants cure by eliminating ethanoic (acetic) acid (they smell
> like vinegar) which is probably a very bad idea here.

Aha, glad you mentioned that - I know that the stuff that I have 
immediately to hand has a vinegar-like smell.

> Secondly, HV finds a way to leak if it possibly can ;-)

Indeed!

> I would try to re-make the 'sandwich'.

Yes, I'd certainly like to look at that route first - mainly because I 
think soldering new wires might be problematic. In response to your other 
message, there's no way to attach any kind of heat shunt; the connections 
at the CRT side protrude maybe 2mm at most. Perhaps heating the entire CRT 
in a oven would be helpful if it comes to it.

> Do you have any idea as to the voltage involved?

No, but it's a small screen - 5" diagonal or so. I did find a service 
manual for a 1330 display, which appears to be a very similar animal but 
without the storage functionality, and that operates at ~ 3kV.

cheers

J.