On Dec 9, 9:48 am, "William R. Walsh" <
wm_wa...@hotmail.com> wrote:
> Hello all...
>
> A number ofneonsigns were recently delivered to me in nonworking
> condition. All but one are driven by an Evertron 2610 power supply.
> Surprisingly enough, this power supply and sign combination were made
> in the US. Nearly all of these signs did continuous duty, shut off
> only by power outages.
>
> The Evertron 2610 power supply is a pretty simple affair. It bases
> upon an IRF2153 driver IC and two IRF730 MOSFETs. The output from
> these is fed into a transformer that looks not unlike a TV flyback. As
> found, most of the signs would start and then shut down. Through some
> very interesting circumstances, I came to know that the power supplies
> would operate normally if powered from a generator. Protection
> functionality appears to be centered entirely in the IRF2153, though
> there is also a line fuse.
>
> Every capacitor in the power supply was bad. None were visibly bloated
> or distressed...either the ESR had skyrocketed or the cap simply
> registered as open. Most were made by Meritek, a company I had never
> heard of before. With new caps, the first sign starts up and runs once
> again.
>
> However, I'm wondering if theneontube is worn out. The sign consists
> of three formed letters, each of which are supposed to be the same
> color, and one has a notably different (lighter) hue than the rest.
"Neon" tube signs may actually be neon - in which case you can see
through the tube and can see the neon plasma in the center of the tube
and the color is the red-orange neon color. For any other color the
tube in all probability has argon to start and mercury to run and
produce UV to excite phosphors inside the tube. These are cold cathode
fluorescent tubes.
The different color letter may mean the tube (or tube section) has
been replaced with a near but different phosphor combination.
> Also noted are strange hissing noises from the tube (not the power
> supply), the ends of the tubing near the terminal points becoming very
> hot (sometimes to the point of making something start smoking) and
> "pulsing" from inside the tubing. Every now and then, the misbehavior
> will stop and things will be fine for a few seconds, just like a
> failing fluorescent tube.
"Hissing" - arcing at the connection? - would also produce heat
Corona discharge? Are the tubes clean?
If the tubes light my guess is problems are in the power supply, or
external wires and connections.
>
> Throughout all of this, the power supply remains cool and seemingly
> stable. It is rated for 5.5kV and 27mA current output, though I have
> nothing with which to safely test this.
Neon sign power sources, like other discharge lightning ballasts, are
essentially constant current. When shorted they will produce only
about 30mA (some are a standard higher current). When the sign is
running the voltage might be 80% of the rated voltage.
>
> I'm wondering if theneontube has simply become weak or damaged at
> this point. All parts of the sign were made by divisions of Everbrite
> Electronics, and it sure seems "convenient" if they would all fail at
> roughly the same time.
>
> How doneontubes act when they fail?
If you have multiple signs can you wire between signs to substitute
power supplies and tube sets to determine what works and what does
not?
You might try sci.engr.lightning. It is not real active but has some
very sharp people.
--
bud--