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G07 Monitor - no picture


SNESNESCUBE64

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Here was a quick repair I did last night. It was on a G07 arcade monitor that came out of a centipede cabinet. When tested on the bench, I got no picture whatsoever. Looking closely, I heard no high voltage and saw no neck glow. What's nice about the G07, is that it is one of the easiest monitors to work on, it is as simple as unplugging thing the yoke, degauss coil, and anode cup, then remove two screws. Afterwords the chassis will slide right out! This monitor was in pretty good shape, it seemed to be completely untouched, which is fantastic because I didn't have to worry about operator shenanigans. Only real glaring problem was its burn in.

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Just as a note, this is a CRT repair, don't try this at home unless you are comfortable working with high voltages that can really hurt you

So the first thing to do when you get something like this, is to follow the G07 flowchart, which will give you a lot of good info to follow. First thing to check is the fuses. I could hear the degauss coil charging up when power is applied, so I know the main fuse wasn't blown, the next place to check would be F901. If that fuse blows, then odds are your HOT (Horizontal Output Transistor) or your flyback is toasted. The first thing I checked was the HOT, as that is a bit easier to test. First thing to do when testing the HOT is remove it out of circuit, on the G07 it is as simple as removing the three wires from the large 2sd870 bottle cap transistor near the flyback as well as the capacitor hooked up to it. From there I tested between the base and collector and the emitter and collector. The way you do this is to set your multimeter into diode mode and measure the voltage drop. A good reading should be somewhere between 0.4V and 0.7V. If you are measuring 0, your HOT is no good and it's time to replace it. In my case, I verified that the HOT is probably alright as I didn't measure any dead shorts.

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So since it was probably not the HOT, it was probably the flyback. I just went ahead and just replaced it, as original G07 flybacks tend to have a bad reputation anyway. (New one on top, original on bottom)

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After replacing the flyback (and fuse F901), I fired up the monitor. It worked perfectly. After dialing in the focus and brightness, it looked pretty dang good.

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The only thing left to do now for this guy is change the capacitors, as they all seem to be the originals and are probably near their end of life if not long past. For giggles I decided to check the tube's health just to see how nice it was. Turns out it was a pretty healthy tube!

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Edited by SNESNESCUBE64
broken picture links

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Thanks for sharing. I have very little understanding of this type of electrical work, but I find it fascinating and would love to get into it some day.

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5 hours ago, DoctorEncore said:

Thanks for sharing. I have very little understanding of this type of electrical work, but I find it fascinating and would love to get into it some day.

Anyone can learn, there's tons of resources online that you can read up on. It's super rewarding bringing things back to life like this.

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