Diagnosing that improperly working favorite collectible neon sign trouble
There you are, proudly displaying that neon sign you always wanted. Your friends come over, and it's downstairs to the bar for a drink. You turn that favorite sign on and all it does it flicker. Or even worse, it doesn't even light! Just great. Now what?.....
Neon is a super collectible. However it's worth a lot less when it doesn't light up. How do you go about diagnosis of a neon sign that fails to light properly? Well, I'll walk you through what I know right now if you have some time. No, it won't be too long. Well, if you read really really slow maybe. Ready? Hope so, you've seen me say this before, and it is true, knowledge is a good thing! I will help you diagnose your neon sign troubles right here on this page.
Now I'm not a neon sign shop guy. I'm just an avid neon sign collector. I'm relating to you what I have learned from trial and error! My words here are not gospel by any means. I'm just trying to help out fellow neon appreciators. Please, if you feel uncomfortable with any test or procedure I list here, don't do it. Seek a professional's assistance.
Here's a basic drawing of a neon sign's components:
In the diagram you can see the components I'll be discussing below when we diagnose and repair your neon sign.
- Transformer (high voltage power source)
- Glass neon or argon tube (illuminating part)
- Hanging chain
- Metal sign frame (signs may have plastic backings instead of metal)
- Electrode to wiring connection with insulating boot (connects power to the glass tube and insulates from grounding)
- GTO wiring (very flexible high-voltage wire)
- Tube support (glass or plastic, many times tie-wired)
- Double-back tube bend (sets connecting tubing back from the face)
- 110-120V plug (for connection to wall outlet)
- Pull-chain switch (turns the transformer on and off)
Get an understanding of the construction and terminology? Good. Let's get into diagnosing your problem neon sign.....
#1) Neon signs with heavy weight metal transformers.
A neon sign that wont light up at all is the first thing we'll cover. I'm talking about your typical 1970's or 1980's beer neon sign. The kind with a big heavy metal box for a transformer. We'll get to the electronic transformer signs later in #4. Let's assume the worst. Flea market purchase. Seller says works great, $125.00, check it out. You look the neon sign over and all the glass tubes appear to be intact. It looks fine to you at the time, but there's no where to plug it in. So you take a chance and buy it. Now it's home and you want to try and light it up.
We already looked over the sign's tubes for breaks when we bought it, or should have, that is step one! If that hasn't been done, it's time to do it. Some tubes are really tricky to follow completely, but it has to be done in a complete and thorough manner.
Verify the cord feeding the transformer is not cracked or frayed before plugging any neon sign's transformer into any electrical outlet. Check for cracks near an end which is very common. If you find some cracks, don't sweat, we just want to test this sign. It's not ready for display yet. Any bad wire spots or cracks will need to have physical separation of the three conductors. Then they will need to be taped with electrical tape individually.
For testing purposes only, I have split a bad spot in a cord open further so I could separate the conductors and tape them individually. This is not a permanent repair by any means. This is a test procedure. We are trying to determine the neon sign's operating condition. If the input power cord's insulation has deteriorated to the point of crumbling at touch, I strongly suggest opening up the transformer to verify there are no crossed bare wires inside. You may end up having to replace a power cord just to test a neon sign. Again, if you are unsure or uncomfortable with any testing or repair, don't hurt yourself. Seek a professional's assistance!
Once we have established the power cord will not short out and pop the breaker or fuse and make your wife or kids yell the T.V. quit, we can move on in our pre-test inspection. Now check the insulating rubber covers over the electrode connections as well as the GTO wires themselves. Look for signs of arcing or burns on the boots or wires. Arcing or burnt marks indicate a short to ground from the high voltage sent through the tube. If all looks O.K; plug the sign in. If it doesn't light right up, try the switch. Most beer neons have a pull-cord switch. Lights up now? Hey, there you go. You a have a working neon sign! That seller at the flea market didn't lie after all! If you get a chance tell him you appreciated his honesty! But let's say it still won't light up. Now what? Well, time to open some things up.
Most older metal case transformers have a small rectangular cover on the transformer itself. That is a removable cover for switch replacement. Pull-chain switches fail rather often. Probably why to this day they still cost $2.99 like they did in 1985.
To check the switch, first UNPLUG the sign! Open up that little cover. Usually it will only have one screw. The other end of the cover notches into the metal to secure it. Once that is open, disconnect the switch's wires. Connect the wires that went to the switch together to bypass the switch. This will provide direct power to the transformer. Wire nut or tape the connections so they can't short out while we do another test. Plug in the sign. It lights now? You need a new switch. Go to the hardware store and buy one. Congradulations, you bought a good neon sign! The neon sign won't light still? Let's keep diagnosing that neon sign.
At this point we will have to disconnect things further. Again, and I do say this often - UNPLUG the sign! Time to disconnect the transformer output leads from the tubes. Most of the time the rubber boots over the electrodes will be stuck in place. Try a gentle twisting motion of the boot with one hand while supporting the glass tubing with the other hand. Stuck? Cut it open with an X-acto knife or a razor blade. Start at the large end by the glass. Cut back an inch or so and try to peel the boot open from off the glass.
On very old signs (pre-1984 or so), there may be a crimped sleeve on the wires to secure the connection. I usually use a pliers or Vise-grip to work the crimp loose. Squeezing opposite of how it's crimped to open it up. Then you can usually slide the wires loose from the crimp, even if it is one wire at a time. On even eariler signs (pre-1973 or so), the connection may be contained in short glass sections that have short boots on the ends. Those wires may have brass connectors that hold the wires secure with a screw or two. Just unscrew to disconnect. Twisted together wires just need to be untwisted. Now it's time to be really careful and being brave helps too.
Take the two transformer output leads that you disconnected from the tubes and space them apart about 3/4 of an inch. Use electrical tape to keep the wires separated. The best way to do this is by allowing the wires to hang over the edge of the table or workbench you are working on. Keep as much distance as you can from the work surface. Preferably 4 inches or more. We want these wires to be in mid air, not near anything or anybody for this next test. Standing clear of those wires, plug in the transformer. An arc should be produced if the transformer is any good. Do not leave it plugged in! If you see an arc, stop and immediately unplug the cord.
A strong blue-yellow arc means the transformer is good. Remember, we are talking about an old-style transformer with a metal case here. This check can not be done with an electronic transformer! No arc, the transformer is bad. You need another one. That is most probably why the sign did not light. Weak or yellow arc? The transformer has seen better days. You need another one. However there still could be a cause for the transformer failure lurking elsewhere in the sign. I have arc, so why isn't the neon lighting up? Well, no answer yet. We will need to do more testing. Time to test individual neon tubes if the transformer made an arc. We can use the diagnostic procedures explained below in #2 checking a flickering neon sign.
#2 Diagnosing a flickering neon sign.
When trying to diagnose a flickering neon sign, basically tubes and all connections are what needs to be checked out. We are going to spend the most time on these next test procedures if you started with me from the top of this page. First off, UNPLUG the sign! Second, the connections at the electrodes need to be checked. Every single one. This includes the connections at the wires from the transformer, as well as the connections where GTO wire connects between tube to tube. Most of the time the rubber boots over the electrodes will be stuck in place. Try a gentle twisting motion of the boot with one hand while supporting the glass tubing with the other hand. Remember, glass doesn't like to be bent much. Stuck? While supporting the glass tubing with one hand, cut the boot back an inch or so with an X-acto knife or a razor blade. Start at the large end by the glass. Once cut, try to peel the boot open from your cut off the glass.
On very old signs (pre-1984 or so), after the boots are off you may find crimped copper or brass sleeves on the wires to secure the connection. Use a pliers or Vise-grip to work the crimp loose. Squeeze opposite of how it's crimped to open it up. Then you can usually slide the wires loose from the crimp, even if it is one wire at a time. On even eariler signs (pre-1973 or so), the connection may be contained in short glass sections that have short boots on the ends. Those wires may have brass connectors that hold the wires secure with a screw or two. Just unscrew to disconnect. Twisted together wires just need to be untwisted obviously.
Since the sign flickers, we know the transformer may still be good. Note I said may be good. Pick a tube, any tube and connect the transformer's leads to just one of the neon signs' individual tubes. I usually start with a tube that already has one end connected to the transformer. You need to make sure you are checking only one tube at a time. To ensure that, disconnect every tube from every connection. With that first tube connected up and clear of shorting out, plug in the cord and see if the tube lights O.K. If it lights with no flicker, that tube is good, and the transformer is looking O.K. too. Didn't light? Probably bad, continue onward. UNPLUG the sign again!
Disconnect the two wires from the first tube and connect the wires to another tube. Plug in the cord and see if that tube lights O.K. If that tube lights with no flicker, that tube is good, and the transformer is looking O.K. too. Didn't light? Probably bad, continue onward. UNPLUG the sign again! Disconnect from that tube and move to the next. Repeat the procedure until all the sign's tubes have been checked over. Remember to UNPLUG the sign each time you move to another tube. Eventually you will find the bad tube. It will flicker just as the whole sign did when connected, sometimes causing a buzzing or humming noise in the transformer.
The flickering problem tube could be caused by a bad electrode or a tube with low gas pressure inside. A neon sign shop would have to perform the repair. Expect to spend $35.00 to $65.00 on a "neon unit" repair, depending on where you live. Go ahead and untie the tube so you can take it in for servicing.
You can re-connect the signs good tubes as they were. A section of GTO wire can be used to "jump out" the bad tube or tubes temporarily until the repaired tube comes back from the neon shop. If every tube did not light, you missed something. Re-start from the top, I covered a complete neon sign diagnosis.
#3 Diagnosing electronic transformer neon signs:
When attempting to diagnose a neon sign with an electronic transformer, things are different than old-style metal transformers. Understand that electronic transformers are designed to shut down when there is a problem. Therefore, standard age-old procedures will not work.
First, UNPLUG the sign! Second, verify all connections are not corroded. As mentioned in the #2 section, check both transformer to tube and tube to tube connections. Find corrosion? My personal expirience is that 90% of the time you find one or more corroded, powdery connections, the electronic transformer will have failed. Why? Mainly because the circuitry that controls the transformer can only tolerate an abnormal load being pushed upon itself for so many times. Remember, they are designed to shut down upon a detected fault. How many times they will do this is a whole different matter! You can try to light the sign again after finding and cleaning dirty or corroded connections. Maybe you will "luck out" and the sign will light!
After checking connections, the next step is best done with another transformer. I think it's best if you have that spare old style transformer from that old beer sign you knocked down the basement stairs years ago. Of course a known good electronic transformer will work as well. Don't have a spare transformer? That can be a problem in properly diagnosing the sign. You need the transformer to check the individual tubes as explained in the #2 section. However there is one other thing to consider - if you have a known good neon or argon tube, connect it to the suspect electronic transformer. If it lights - the transformer is good. Now you can check individual tubes on suspect sign as in #2 above!
#4 Diagnosing a partially lit or dimly lit neon sign.
When trying to diagnose a partially lit or dimly lit neon sign, The testing is basically for shorts to ground or for bad tubes. First off, UNPLUG the sign! Start by looking for burnt boots, signs of arcing through a boot (like discolored pinholes) or dark spots on a glass tube.
Find something suspect? Open it up. Time to disconnect the rubber boots over the electrodes. Remember, glass doesn't like to be bent much and most of the time the boots will be stuck in place. So support the glass tubing with one hand and try a gentle twist to the boot to remove it., No luck? Try cutting the boot back an inch or so with an X-acto knife or a razor blade. Start at the large end by the glass, supporting it. Once cut, try to peel the boot open from your cut off the glass.
On very old signs (pre-1984 or so), after the boots are off you may find crimped copper or brass sleeves on the wires to secure the connection. Use a pliers or Vise-grip to work the crimp loose. Squeeze opposite of how it's crimped to open it up. Then you can usually slide the wires loose from the crimp, even if it is one wire at a time. On even eariler signs (pre-1973 or so), the connection may be contained in short glass sections that have short boots on the ends. Those wires may have brass connectors that hold the wires secure with a screw or two. Just unscrew to disconnect. Twisted together wires just need to be untwisted obviously.
Since the sign lit dimly, we know the transformer may still be good. Note I said may still be good. Pick a tube, any tube and connect the transformer's leads to just one of the neon signs' individual tubes. I usually start with a tube that already has one end connected to the transformer. You need to make sure you are checking only one tube at a time. To ensure that, disconnect every tube from every connection. With that first tube connected up and clear of shorting out, plug in the cord and see if the tube lights O.K. If it lights, that tube is good, and the transformer is O.K. too. Didn't light? Probably bad, continue onward. UNPLUG the sign again!
Disconnect the two wires from the first tube and connect the wires to another tube. Plug in the cord and see if that tube lights O.K. If that tube lights, that tube is good. Didn't light? Probably bad, continue onward. UNPLUG the sign again! Disconnect from that tube and move to the next. Repeat the procedure until all the sign's tubes have been checked over. Remember to UNPLUG the sign each time you move to another tube. Eventually you will find the bad tube. It will not light, sometimes causing a buzzing or humming noise in the transformer.
The problem neon or argon tube could be caused by a bad electrode or a tube that has lost it's gas pressure inside. A neon sign shop would have to perform the repair. Expect to spend $35.00 to $65.00 on a "neon unit" repair, depending on where you live. Go ahead and untie the tube so you can take it in for servicing. Re-connect the signs good tubes as they were. A section of GTO wire can be used to "jump out" the bad tube or tubes temporarily until the repaired tube comes back from the neon shop. If every tube did not light, you missed something. Re-start from the top, I covered all types of neon sign diagnosis on this page.
Well, I sincerely hoped I could help you out with your non-working neon sign. May it light brightly for decades to come! Thanks for allowing me to help, it really wasn't any bother at all.