Quick ‘N’ Easy Troubleshooting - L1800 Mainboard

If you have an L1800 printer that doesn’t seem to be working quite right, you’ve come to the right place. My name is Kevin, and today I’d like to go over how to troubleshoot the mainframe of an L1800 printer. There are a few ways to do this, but I aim to cover what I believe to be the quickest and easiest way. This article accompanies a video I recently posted on my YouTube channel, Kevin at BCH, where I also have hundreds of other helpful printer-related videos.

About the Printer

The L1800 printer is most commonly used for DTF printing. For the video demonstration, I used two different L1800 motherboards that gave me problems as an example. I also showed a good L1800 motherboard for comparison. If you’re watching along with the video, you’ll see that the good board has a BCH seal. This means that we’ve tested it and ensured it works properly. If you need a tested board, you can go to my website, BCHTechnologies.com, which I’ll link below. You can find it by entering “L1800” into the search bar.

Heat Sync

The board still had the heat sync on it, so I started by taking that off. This will make it easier for me to troubleshoot it. You need a number two Phillips screwdriver to take off the heat sync. Then all you have to do is remove the screws holding it. The two screws on the bottom will differ from the other screws you’ll be removing. These two screws are more spiraled than the others, and their threading is less fine than the screws that attach to the transistors.

Components

There are many components on the mainboard, all of which can be tested using a multimeter. However, you’ll have to be able to figure out which part is which to determine how to test them. You can go to my website and type “auto” into the search bar. The one you want should be the first search result, labeled “Auto-Detector Epson/HP/Canon Mainboard.”

This mainboard testing tool can automatically detect which component you’re trying to test. Even if you don’t need the tool, its store page contains a list of all of the typical markings on an Epson board and what they stand for. For example, “R” is resistor, “F” is a fuse, and “VR” is a breakdown diode.

Auto-Detector

When you order the auto-detecting multimeter from my website, you’ll notice that it has a lay-down battery, which means you won’t have to go through the trouble of installing any yourself. It also has a USB charging cable to charge the tool from your computer. The tool comes with a few testing components, like an LED light. It will be shipped pre-charged, but if it’s not turning on, then charging it before use can solve the issue in most cases.

The tool also comes with three props, and I should probably go over the slots you’re going to insert them into briefly. Simply put, one is one, two are two, and three are three. You can put any single-color ones to the one spot, a two spot, or a three spot. The multimeter comes with a tool for calibration that has three prongs on it. Insert one prong into a one spot, one into a two spot, and one into a three spot. If you lose this tool, don’t worry too much. It’s unnecessary because you can calibrate the multimeter with anything that can connect a one spot with one of the two or three spots.

Once you’ve inserted the calibrator as instructed, press start, and it will automatically go into self-testing mode. Let it run, and then in the middle of the testing, it will ask you to remove the props. Go ahead and remove it, letting the test run until it’s finished. That’s all it takes to calibrate the multimeter.

Pick any labeled spot to insert the first prop. Then find a place labeled two for the second prop. Then the third goes into one labeled three. Simple enough, right? From there, testing a component is easy. Just connect to the legs. It doesn’t matter if it’s one, two, or three. Just pick any two connectors and press start.

If you’re watching the video, then you’ll see that it immediately figured out that I was testing a diode. This demonstrates that it automatically knows what it is, detects the range, runs the test, and feeds you the results. I must warn you that if you have a large resistor and didn’t connect the pin securely, it will automatically detect it as a capacitor. So if you really need to know the resistance of a larger resistor, then you’ll need a multimeter.

How to Use the Multimeter

If you look at the motherboard, you’ll see that other than the row of transistors, most of them are either labeled “R” for resistor or “C” for capacitor. These are typically used for cleaning out the electrical current that runs through the board. Transistors are usually okay, and you’re most likely to blow out a capacitor.

Next, you want to look for a component marked “F,” which stands for fuse. Nearby will be one labeled “TP,” which stands for testing point. “QF is going to be a transistor or a MOSFET. “IC” is an integrated circuit. “C” is a connector in this case, and sometimes will also show the color of the connector. You’re looking for the fuse, whose label will always start with F.

Because the other side is transistors, I’ll use the multimeter to test it. You’ll hear a beep when you touch the tool tips to the board. This means that it’s a closed circuit. If you don’t hear a beep or see that the circuit is open, you can go to BCHTechnologies.com and type F1 or F2 into the search bar. You’ll want the “F1F2 Fuse for Epson L1800 DTG DTF Printer.”

Next, I’m going to test the four transistors. Because they are in the circuit, they are mounted on the board. You can’t test it on the board as the transistors. A quick way to try it on the board is to pick the first and the third transistors (or the second and fourth), it should be a closed circuit at a round 43 OLMs. It’s the same method for both pairs. The second pair should be an open circuit, or it might show up as a capacitor on the multimeter. The two pins on the right will have no resistance.

Now that I’ve shown what it looks like on the good board, it’s time to move on to one of the problematic boards I have for the demonstration. On the first pair (one and three), we have 42 OLMs, which is good enough. The two middle have no resistance. This is sometimes a good thing. If they aren’t a closed circuit, the two middle pins aren’t necessarily bad at 0 resistance. If you have a closed circuit, though, and they don’t read very high, they must be bad. I marked the one I believed to be bad with a marker and moved on to the second problematic board.

The Last Two Boards

As with the first troubleshooting board, I tested the first and third as a pair. However, unlike the other board, these two were bad. I tested the second pair (the two and the four), and they were okay.

If you need a new transistor pair, you can go to my website and type “L1800 transistor pair” in the search bar. You should be able to find a number on your transistor, which you can use to make sure the replacement ones match it. The numbers for mine were a2210 and ca0a2.

I hope this blog helped! Follow me on YouTube at Kevin at BCH for more helpful printer videos!