Repairing an Epson Printer's Main Board

The issue we’ll be talking about today is the Epson Printer mainboard. This specific problem causes your printer to fail to turn on when you tell it to. This could be caused by several things, including a burned-out power supply or motherboard. Today we will be focusing on the latter. A good indicator that the motherboard is the issue is a burning smell when trying to turn it on.

We will have to remove the scanner, which you can learn how to do from this video. There will be a screw above and a screw below the power supply. Remove both of these to take the power supply off. You should see a white cable and a black cable and a white cable with black wires. Both of these cables should have the blue side facing left. You’ll also see two screws on the top side of the board.

Remove those and unplug the small cable on the bottom. Once that’s done, the board should slide right out. The square chip on the back is what you’re paying money for. Fortunately, most of these malfunctioning chips are cheap enough to replace.

Burned-Out Driver Chip

The driver chip can sometimes get burned out. You'll see two chips right next to each other on the board. We will be working on those two, as they’re incredibly likely to be burned out. This is the first thing you should check. If you shine a light on them, you should see some letters.

If you need a new part for your printer, you can go to my website and order new ones. You can find the parts we need today somewhere on this page. It will be under the mainboard tab to the left.

You can test the part you order, which I strongly recommend doing, using a 12864 tester. You can buy this tester on eBay for around 10 USD. With the letter facing you, push the red button, and it should tell you if the part is good or not.

If you only have a multimeter, you can also use that to test it. It won’t be as effective, though. It will tell you if the part is not broken, but it will not necessarily tell you whether or not it’s good. If you want, you can test the old transistors too before buying a new one. You cannot test them on the board, though.

Transistors

If the first transistor is a PNP, the next one must be an NPN. When you test them, the side with the letters should be facing you. Do not test them on the board, as the readings will be inaccurate and won’t make any sense. If you try the transistor and it seems to take a long time to get your results, chances are that the part is bad.

Next, we’re going to need a soldering iron. If you don’t have one of those, you may be able to find an alternative if you look around a bit on YouTube. You can see how to do the soldering part of this process at around the six-minute mark in this video from my YouTube channel.

While doing this process, I decided to connect a couple of the cables to try it out and make sure it worked before I went through all the effort of screwing it back into place. Do not do that during your repair process. The most critical cables are on the front panel and the power cable.

I was lucky, and it worked. The board should be sitting on a little notch when you put it in. You’ll have to pull a black lever back on the left side. Then, when it falls back, it should go right into the two slots on the motherboard.

Now all that’s left to do is put everything back together, and your printer should be working good as new.

For more helpful videos, visit my YouTube channel, Kevin at BCH. You can also watch a more detailed video of this process by clicking here.