There aren’t any “magic bullets” when testing electrical components
By George Lanthier
If you travel the Internet, you will see dozens of postings about component failures and guys going nuts over these failures and the testing of both conventional and solid-state ignition systems. When you cut through all of this stuff you quickly see that what everyone is looking for is a silver or magic bullet. In addition, some don’t even believe in time-proven methods and, if you can believe it, are not even convinced that many of the problems they gripe about can be found using nothing more than an electrical and electronic industry standard: the V-O-M or Volt-Ohm-Milliameter or multimeter.
In reality, there’s really a lot more going on here than just knocking the product or wanting a quick fix, in my opinion it shows a lack of training and knowledge in three important areas:
- A lack of expertise in electricity and electronics; the first we should know, the second isn't really our field, so don't criticize those who are in the field of electronics.
- A thorough knowledge of a V-O-M. There are still too many of us that don't own a multimeter and that's our fault, no one else's.
- Good electrical troubleshooting procedures.
In the age of transformers it was considered easy to test an ignition system and, in my opinion, it still is, but I see too much criticism from some of ways that have worked from day one and I base that on the fact that many who claim to teach, don’t know what they need to know to do it. So, with that said I’m going to jump in and give you my spin on this whole thing with a few passages from our new book WIRING & Fuelburning Equipment, Book One, Fundamentals.
The procedure I’m about to outline can be found in books on heating and also on electricity back to the 1910s, and when something has been around that long, in my opinion, it’s gospel. In addition, and although there are many procedures and testers for testing a conventional transformer, the most basic procedure to test the conventional ignition transformer is the oldest and requires only a well-insulated screwdriver free of cracks and damage. I get a lot of criticism from some people about teaching this, but again, and in my opinion, most of my critics don’t know what they even need to know about electricity to make the criticisms. I am much less concerned about someone working on 10,000 volts at 23 milliamps than someone going into an ungrounded 120-volt circuit with 15 amps of potential and I’ve already pretty much beat the subject of proper grounding to death.
The facts are that you must learn to work with and respect all voltages and more importantly the amperages around HVAC equipment and if you know what you’re doing, then this is a lot less dangerous than a lot of other procedures. If you don’t know what you’re doing learn, and if you don’t want to learn, well, just stop reading and go away.
In Figure 1 you see this procedure illustrated.
Note: Do not perform this test on solid-state ignitors, and refer to the manufacturer’s literature for correct testing procedures.
- Take a well-insulated screwdriver and place the shaft on to one of the two ignitor terminals.
- Turn on the power and bring the tip of the screwdriver to the other terminal.
- Pull the tip away and a strong spark of at least 1/2-inch should be created and maintained.
- If the transformer will not pass this test, replace it.
In Figure 2 you see a procedure for checking electrodes.
The testing of electronic ignitors is a little bit more complicated. Although the screwdriver test, as shown in Figure 1, is permitted by some manufacturers, not all of them encourage it or endorse it. Before you perform any of these tests make sure the respective OEM approves of it, and even if the OEM does allow it care must be taken not to directly short the terminals without a spark between them. In many cases it will short out the ignitor and destroy its internal circuitry. Keep in mind that ignitors are not merely a pair of coils, but rather a complex electronic device made up of several electronic circuits and components.
- Place a booted jumper across the ignitor tips.
- Again, take a well-insulated screwdriver and jumper the shaft to a known ground.
- Turn on the power and bring the tip of the screwdriver to the surface of the ignitor.
- There should be no arcing across any surface of the ignitors.
- Check both ignitors and if the ignitor insulators will not pass this test, replace them.
The first basic test for ignitors is to place an ohmmeter across the ignitor output terminals with the power off and measure the resistance from each ignitor post to ground, Figure 3. Normally the ignitor is considered good if the resistance from each post to ground has no more than a 10-percent difference between posts. Each OEM is different and they should be consulted for the proper output range and differential. It’s also important that you verify continuity, or a short between the ignitor case ground and true ground; again, in my opinion, this is a major part of any electrical test.
Another test that can be done and is approved by most manufacturers is to bring the ignitor output terminals to within one-quarter to one-half of an inch apart and turn on the power, Figure 4. A strong blue spark should be generated. Another trick is to let it spark for a few minutes, five to 10 in most cases, and see if the spark changes from blue to orange. If it does change, I would replace it.
Finally you can check both ignitors and transformers with a common method and in addition really put the ignitor under the gun, so to speak. Bring the ignitor or transformer output terminals to within one-quarter to one-half of an inch apart. Place a milliameter in series with the hot line going to the ignitor and turn it on, Figure 5. Again, the reading should stay steady and not vary for at least five minutes with a strong blue spark throughout the test, and also stay within 10 percent of the rated amperage draw for the device.
As of the date of this article many of the “silver-bullet testers” for all of these devices are questionable in their results, from what I’ve seen, read and heard. Based on my years of field experience the tester shown in Figure 6 works for ignition transformers and in addition will act as a backup ignition system that can be used for a night or weekend or longer.
Many of the testers being sold for the testing of transformers and ignitors are simply looking for a voltage range, a voltage presence or some other unreliable quantity. Some are looking for a radio-frequency field that can also be generated by nothing but a fluorescent lamp ballast, so investigate them carefully and really check into this before you spend your money. If you are determined to spend money, invest in a good multimeter; it is money well spent and you’ll find has a multitude of legitimate uses. There are no “silver bullets” out there and if you haven’t heard, the Lone Ranger has passed on, sorry about that.
Finally, the most important tests of all. Before performing any of these tests, verify the incoming voltage to be 120 volts AC, that all of the grounding on all of these circuits be properly checked and found to be present. To do that requires a multimeter to quantify and qualify those values and if you don’t then this whole article was a waste of time, yours, mine and our industry’s.