When a monitor just has a black screen, it’s a pretty good indication that it’s not getting power. The typical places to start with this kind of issue would be the power cord and the HOT, but lets say that you’ve checked them and they are not your problem. Where do you go from here? In this post, we will discuss how to check diodes on your monitor chassis to make sure that they are in working order.
Checking Diodes On An Arcade Monitor
The diodes we are talking about are located in the power supply section of your monitor chassis. There are usually about 4 or so located right in a row in this section. Examine your monitor chassis and see if you can find them. In the video, ours were located near a large capacitor. Once you have located these diodes, you can check to see if they are shorted or not.
Before we begin, you might want to refer back to our post on Checking Fuses With A Multimeter to get familiar with the diode test settings on a multimeter.
The process of checking a diode is very similar to checking a fuse except that the indicators are reversed. When we checked fuses, we wanted our meter to generate a long beeping sound or a 0 (ZERO) ohm reading. If our meter reads this while we are checking a diode, this indicates that it is shorted and is not working properly. Shorted diodes can be caused by many things including hooking up power to an arcade monitor that requires an isolation transformer. Always be sure that you are using an isolation transformer on monitors that require it.
If you find a shorted diode, you need to replace it. Desolder it from your board using your desoldering iron or solder wick and solder the new one into place. Always make sure that you replace the shorted diode with another one that has the stripes oriented exactly like the original diode. Also, be sure that all of your power wiring to your monitor is correct before turning it back on. Doing this will save you from damaging another diode and having to repeat this process over again. Once you have replaced these shorted diodes you are finished with this part of your repair.
Sometimes a black monitor screen can mean more than just a power cord or HOT issue. Knowing to check your diodes before moving on to more complex repairs can save you lots of time and effort. Please feel free to leave any questions or suggestions in the comments section below.