Neon Sign Repair Questions

[William R. Walsh]

Hello all...

A number of neon signs 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 the neon tube 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.
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.

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.

I'm wondering if the neon tube 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 do neon tubes act when they fail?

William

 

[bud--]

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--

 

[William R. Walsh]

Hi!

"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.

Each sign is made up of two tubes. The topmost tube is definitely a
neon tube. There is a tube on the bottom that glows white, but I think
it's a coating on the inside of the tube that makes the white color,
like a regular fluorescent bulb.

The different color letter may mean the tube (or tube section) has
been replaced with a near but different phosphor combination.

The letter in question is part of a larger tubing structure. I can't
think it's been replaced...the sign has barely ever been dusted!

"Hissing" - arcing at the connection? - would also produce heat
Corona discharge? Are the tubes clean?

The more I look at it, I think it's got to be arcing. The power supply
itself is silent, at least as close I've dared get to it while the
sign is in operation, lest it blow up. From what I can tell, again
being nervous about getting too close, the noise is coming from the
tube near the connection points.

The sign is a lot less filthy than it was. It's still pretty dusty in
some areas that are hard to reach. I don't want to get too
rambunctious with cleaning it.

The connections look pretty shifty to me. They are simply wires
wrapped around the leads coming out of each tube and covered in a
rubber boot. I'd have really expected something better. The wires
coming from the power supply look OK, while the ones coming from the
tube are black in color. I'm having a hard time deciding if they were
made that way, or if they have somehow oxidized.

If the tubes light my guess is problems are in the power supply, or
external wires and connections.

The tubes start right away and do light but are rather unstable.

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?

I don't yet have the other signs on premises. The two I have now are
different. When I get more of them, I plan to try swapping parts to
see what works and what does not.

William

 

[bud--]

On Dec 12, 1:01 pm, "William R. Walsh" <wm_wa...@hotmail.com> wrote:

The connections look pretty shifty to me. They are simply wires
wrapped around the leads coming out of each tube and covered in a
rubber boot. I'd have really expected something better. The wires
coming from the power supply look OK, while the ones coming from the
tube are black in color. I'm having a hard time deciding if they were
made that way, or if they have somehow oxidized.

Probably a common connection method - it is only 30mA. Black sounds
odd - you could try scraping. Leads from the tube may be pretty
fragile. You could run it without the insulator boot and look for
arcing.

--
bud--