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Apr 30, 2011, 12:43 AM
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EL Backlight Troubleshooting Steps

Help, by EL backlight doesn't work!
Its been a common theme lately. I've answered the same question so frequently that its about time I post a set of steps for all to see!

First off, please take comfort that the vast majority of problems are not a result of a faulty board or EL panel. Its usually something simple. I test each and every unit prior to shipping. That's not to say I can't make a mistake... I can (and do!)... but even then its usually a simple fix.

Before we get too far into troubleshooting, let's start with the very basics.

CHAPTER 1: Is there even a problem?
Believe it or not, the most common "problems" aren't really problems at all. These are the four that come up the most offen:
  1. The EL panel is installed backwards. Assuming you have the standard blue EL, it is the WHITE side that glows blue. The blue/green side does not glow at all. If you have one of the other colours, then it is more obvious.
  2. The firmware isn't setup. The stock firmware can't control the EL panel. The various custom firmwares can. Please refer to your chosen firmware manual or support group for instructions on how to enable the light and assign a switch for it. Only once you've programmed the firmware into your radio, then assigned a switch in your firmware and then physically flip that switch, will the light come on.
  3. Some people have reported that their radio had some "gunk" or "varnish" on their radio's pads where the pogo connectors connect with the radio's main board. Its a good idea to clean both the pads and the pins with 99% alcohol prior to installing.
  4. The light is on, but the user is expecting a spotlight instead of a backlight. EL technology "glows", it does not "shine" like a flashlight - nor do you want it to! In the day time or in a bright room, you may not easily see the backlight... but that's OK because you can see the LCD clearly anyway. In the dark, you don't want the backlight to be too bright or it can harm your night vision and you'll crash. The EL backlight is NOT very bright, and that is deliberate. So before you go through the troubleshooting steps, at least look at the light in a semi-dark room to confirm its really not on. If it i still off (or very dim), then continue.

CHAPTER 2: Narrow down the problem

I like to compartmentalize things. The problem is, generally speaking, going to be with either:

A) The EL panel or its wires or connector
B) The add-on board
C) The radio

The trick, of course, is to figure out which.

For most of the tests that follow, you're going to need a multimeter that can measure voltage in both AC and DC. It doesn't have to be a "good" one... as long as it has a setting for both AC and DC, it will do.

Test 1: Ruling out the radio
  • Remove the add-on board (and EL panel unless you're confident that's not the problem) from the radio and set it aside for now.
  • Turn on the radio and flip whatever switch you assigned to the light so that the light should be on (if it were installed).
  • Use your meter to measure DC voltage between Pin 17 and Ground. Refer to the picture below.

Interpret the results: If you get a voltage between 4.95 and 5.05 (or close) then its not your radio so move on to Test 2. If you get a voltage of zero or significantly less than 5v then the problem is with your radio. See the "its my radio" section below.

Test 2: Ruling out the add-on board's electronics
This test is done with the add-on board not installed in the radio and with the EL panel unplugged.
  • For this test, a test lead with two small insulated alligator style clips is useful, but any piece of wire can work. Be careful you don't short the wrong wires though!
  • Take your test lead and attach one end to the pogo-pin (or pad) marked "VDD" and the other end to the pogo-pin (or pad) marked "+5V". [tip: if you find it easier for some reason, any pad, pin or hole on the board marked with a tiny printed triangle is an alternative +5V connection point]
  • Attach the USB cable to the board and plug in to your computer. Caution: At this point your board is now powered! Be sure not to inadvertently short something and don't touch any metal with your fingers! I have no idea if a computer's USB power can kill you, but let's assume it won't feel good.
  • With your multimeter set to measure AC voltage, take a reading between one of the EL pins and the pad marked "GND". Repeat the test between the other El pin and GND.

Interpret the results: We're expecting a reading of between 60VAC and 90VAC on each test (this means the panel is getting 120 to 180 VAC total). If this is what you get, then the board's electronics are not the problem so you can move on to the next test. If you are getting zero V on one or both pins, or one or both are significantly less than 60VAC, then something is wrong with the chip marked "IC2". See the "its my add-on board" section below (although you may want to first confirm you're getting 5VDC between VDD and GND to make sure your USB is properly powered and you've properly jumpered VDD and +5V).

Test 3: Ruling out the EL Panel
Now that we have the board powered and confirmed working (see Test 2), we can test if the panel itself is working. Go ahead and plug the EL panel into the board.

Interpret the results: If it glows, then its fine and you can move on to the next test. If it doesn't glow then the problem is with the EL panel. See the "its my EL panel" section below.

Test 4: Ruling out the pogo connection
We're going to basically repeat Test 1 but with the add-on board installed.
  • Install the EL and board again.
  • Either turn it on, or plug the USB in.
  • Flip whatever switch you assigned to the light so that the light should be on.
  • Use your meter, set to DC, and take a reading between VDD and GND.

Interpret the results: If you get a voltage between 4.95 and 5.05 (or close) then there's nothing wrong with your installation. If you get a voltage of zero or significantly less than 5v then the problem is with the pogo pin connection between the board and your radio. See the "its my pogo pin connection" section below.

CHAPTER 3: Dealing with the Problem

Hopefully the above tests has narrowed down the problem and pointed you to one of the sections below, which will further help you resolve the issue.

Uh-oh: its my radio

Ok, so we've just determined that the problem is with your radio. But don't panic! That doesn't mean that something is actually wrong with your radio, just that the EL isn't turning on because of something to do with the radio. Possibilities include:
  • A firmware issue. Either you don't have custom firmware or you have a corrupted copy or its some experimental version that isn't working properly... who knows. If you're using a version that someone else is using and they can use the EL function with theirs, then this isn't the case. But if you suspect this might be the problem, then seek help in the appropriate forum.
  • You aren't using the firmware correctly. Again, seek help in the appropriate forum.
  • Your switch that you've assigned is bad. Try a different switch.
  • Something actually is wrong with your radio (now panic). This could be a faulty CPU or a bad trace on the circuit board. For some reason Pin 17 isn't energizing as it should. If you've ruled out everything else and suspect this... I don't know what to suggest. Get another 9x! So far I have NEVER heard of this being a problem though.

Whatever the reason, if we've narrowed it down to this section then it has nothing to do with the add-on board or the panel and this is about a far as I can go trying to help. Good luck!

Uh-oh: its my EL panel

The EL panel itself is a pretty rock solid technology and I would really be surprised if we ever see one that's truly "defective" in material. So 99.9% of the problems here are going to be with the connections. If we've narrowed the problem to this section, then the only trick left is to figure out what part of the connection is going wrong. There are only so many possibilities:
  • One of the solder pads where the wires connect to the EL panel has lifted away from the panel. There have been a few cases of this. Try squeezing the pad with some pliers and see if that (at least temporarily) solves the issue. If it does, then we know the problem but you might have to get the panel replaced unless you can get it to stay how it should (perhaps lightly touch it with a soldering iron).
  • The wire is broken. It could be under the shrink wrap where the wire connects to the solder pad mentioned above, or it could just be that the thin wire has an internal break somewhere along its length.
  • The connector is faulty or has come loose.

In all the cases above, you should be able to figure it out by using your meter and testing for continuity until you nail down exactly what is wrong. If its not a lifted pad on the panel then its probably something you can repair yourself. If you can't, then it can be sent back for replacement (see warranty chapter below).

Uh-oh: its my add-on board

If you've narrowed it down to this section, then there's probably not much we can do except have you return your kit to us for test confirmation and repair/replacement (see warranty chapter below).

Uh-oh: its my pogo pin connection

Hopefully you're in this section, because this will be the easiest to fix. The problem is simply that, for some reason, the pogo pin marked "VDD" isn't making contact with Pin 17's pad on the radio. Some things to consider:
  • That pad is particularly small. Many people have reported that simply uninstalling and re-installing their add-on board has magically fixed the problem. In other words, the board was installed just crooked enough to make it so the VDD pin wasn't properly aligned with the Pin 17 pad. However, this could also be caused by shipping damage or poor manufacturing if the VDD pin is not reasonably straight. So if re-installing doesn't solve the issue, take a good look at the pins from the end and side and confirm the VDD pin is more-or-less straight. It doesn't have to be absolutely perfect, but it should be close. If it isn't straight, you can try using a soldering iron to heat it up and re-seating it yourself if you want, otherwise it should be sent back for repair (see warranty chapter below)
  • As mentioned in the tips at the top of this article, it could be just a cleaning issue. Make sure the VDD pin and Pin 17's pad are CLEAN!
  • Also mentioned in the tips, be sure the board is fully seated by pressing down on the board gently around the screws and taking up any slack.
CHAPTER 4: Warranty

If you're reading this then I guess none of the above helped you resolve the issue, or you've determined the board or panel is faulty. Unfortunately, mistakes happen and I'm here to help! You'll need to send your unit back and I'll first confirm the problem and then repair or replace as necessary and send it back to you. It would be good if you can dig up your order number (or make sure you give me your full name at least) and then contact me to get things started.

I hope this document has been comprehensive and clear enough to be useful.

- Steven
Last edited by s_mack; Feb 24, 2012 at 02:26 AM.
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