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Re: Rebuilding a neon
Tesla List wrote:
>
> >From mhammer-at-midwest-dot-netSun Aug 4 13:25:47 1996
> Date: Sat, 3 Aug 1996 23:58:31 -0500 (CDT)
> From: Mike Hammer <mhammer-at-midwest-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Rebuilding a neon
>
> I have acquired 3 Jefferson Electric 12kv 60 ma neon transformers
> free of charge. One unit works fine and is working well on my coil.
> I am trying to rebuild one of the dead units. I unpotted it ok and
> once the tar was off it came to life. However there is some arcing
> between the windings and core. So I have attempted to dismantle the
> core and remove the windings. There are 4 rivets in the corners and
> the windings are contained on a bar along one edge of the core.
> Excuse my attempt at ascii artwork.
>
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>
> The bar containing the windings seems like it should slide
> out of the rest of the core.But it seems quite unmovable.
> Removing the rivets from the rest of the core didn't help.
>
> Also where are the magnetic shunts in this transformer. I don't
> see anything that looks like a shunt plate.It just seems to be a 2 piece
> core.
>
> I have rebuilt 2 Franceformer neons and they were a piece of cake.
> This puppy has me stumped.
>
>
> Mike Hammer
> mhammer-at-midwest-dot-net
Mike -
Ahhhhhh. Brings back memories to me, as I have rebuilt MANY a
Jefferson transformer. What you need to do is pry off the outer
core laminations one at a time, taking care not to kink or bend
any of them. It's a pain, but it's do-able.
The sparks you see are most likely due to tar residue stuck in
the space between the windings and the core. There are 'U' shaped
pieces of mica which are *suppose* to prevent arcing, but...
Once you get that 'bar' assembly off and cleaned up, replace the
mica 'U' pieces with some HDPE plastic.
The magnetic shunts are created by those two 'post' stubs reaching
up from the bottom to the space between the HV secondary windings and
the primary. Easiest way to reduce the leakage (and boost output) is
to clip off every 8th or 10th 'stub' with a pair of snips. (Lightly
tap out any edges with a hammer so that the cores stack neatly back
together.
BTW - You can increase the output current by placing *one* of the HV
secondaries on 'backwards', and wire them in parallel. This will,
however, cut the output voltage in half.
- Brent