HV tracking across flexible PCB strips

Jules Richardson jules.richardson99 at gmail.com
Mon May 11 12:07:00 CDT 2015

On 05/11/2015 08:51 AM, Paul Koning wrote:
> It sounds like a very strange way to construct high voltage wiring.  The
> major rule for high voltage work is to avoid sharp edges.  A strip like
> you describe seems to violate that rule, big time.  It presumably worked
> when new, but it sounds marginal.

I agree, it does seem strange! On the chassis side, there's a rather unique 
terminal clamp which holds the end of the flexible strip. One of the wires 
(I expect it's for the CRT anode) on the other side of that clamp is 
obviously HV cable, but the other two appear to be nothing special.

Sure, I can see a servicing benefit to being able to disconnect the CRT, 
but I don't get why HP couldn't have come up with a different connector 
arrangement and at least used regular wire for the "other two" connections 
between it and the CRT.

> The most obvious fix is to replace it by a set of regular (round) wires.
> Use fairly large wires if you can, not because of the current carrying
> capacity but for the roundness.  Along the same lines, when soldering,
> make sure the joint is smooth, no pointy protrusions on the solder.

Yes, that had crossed my mind - my only worry is soldering at the CRT end 
as I'm not sure if there's a danger of damaging something within the CRT.



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