So I recently picked up a Hantrarex MTC-9000 9" (manual says it's 10", but it's definitely a 9" tube) CRT. Initially, the tube had a lot of gunk, a chip on the face of it (not really visible in the pictures), and did not work initially. This thing was used most likely in a poker machine based on the burn on the screen. I love little CRTs like this, they make excellent test monitors and I think I am going to use it for a future project.

Just as a general disclaimer, CRTs are very dangerous to work on due to the high voltages they rely on for operation. Do not work on them if you are not comfortable with the non-zero chance of serious injury or death that can be caused through mishandling of this old technology. The content in this entry is NOT a guide on how to work on these, but just a log of what I did to get it going.

So to touch on it not working, I noticed that there was no neck glow, indicating that the heater was out. This is one of a few things: the flyback could is bad and isn't making the heater voltage, there is a disconnect somewhere along the line and the heater line was cut, or something in the circuit between the flyback and the tube itself is driving down the voltage for the heater. Without the heater, the CRT cannot operate, as it relies on the heated cathode to make the beam that activates the phosphors. As shown in the picture below, this is what it could look like with no heater.

The first thing I typically do on a CRT is inspect it for damage. This could be burnt components, holes, blown fuses, missing components, bad solder joints, ect. After a quick inspection, I noticed that a few capacitors were actually bulging out the top. Not surprising at all, most arcade monitors are high hour and these electrolytic capacitors have long exceeded their life. What was really interesting is that the main filter capacitor was actually bulging as well, I've never seen one with damage like that before.

Fortunately, I had most of the capacitors on hand, so I just replaced every single electrolytic capacitor on the board (except for one 22uF rated for 200V, I didn't have that one). Typically this kind of thing is the first thing that I do in the troubleshooting process of working on any arcade monitor since bad capacitors are such a big problem with them. If you do decide to work on such, just remember to use higher quality capacitors that are rated for longer life, not just some junk you buy on amazon. Also try to make sure you buy such components from reputable dealers, they are even faking capacitors these days!

Anyway, the monitor fired right up after replacing the capacitors. It still needs some fine tuning and there's a weird issue where the bottom is beginning to collapse. So I will have to investigate further with this one. I also wanna look into swapping the tube with one out of a consumer TV that I have lying around due to the damage on the face of the tueb, but that's an experiment for another day. Overall it has a pretty alright looking image.