Arcade Collecting > Merit/JVL Touchscreen

Ducksan Type 55 - Merit Megatouch XL Question

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yotsuya:
OK, I picked up a Merit Megatouch with a dead monitor. When I got it home and plugged it in, I verified that the board works and puts out video, but the monitor itself doesn't seem to power up (the touchscreen works, though). There's no neck glow, and the monitor itself put out a buzzing noise.

I did some research on Merit's website, and it indicates that in a lot of cases, c804 is a cap that changes values over time and is usually the main culprit with power issues, and that I should replace it (along with a few others) with a larger value cap. I did that just for c804 last night. I fired it back up, and no luck. I still get the same buzzing noise, and no neck glow. I can still replace the others caps, but I was wondering if the buzz is an indicator that something else is bad. I can't pinpoint where it's coming from, so that's an issue because I'm not sure what to replace. It's interesting, too, because when I power down, the buzz doesn't stop immediately but powers down as well. It reminds me of a fan gradually shutting off, if anything.

I shot some video of the monitor. The buzz you hear in it comes from the monitor. If anyone has any insights, I would appreciate it. This is my first attempt at CRT repair, so I really want to learn from this.



Thanks!

grantspain:
i would suggest reading the HOT with a muiltimeter

yotsuya:
GrantSpain-

Thanks for the tip. I have a multimeter, but I confess that I am not proficient with it. Any suggestions on what to set it to, as well as how to test the HOT?

grantspain:
the hot will be something like a bu2520 or 2sc5144 located on the flyback heatshield,set multimeter to diode test and read centre leg to heatshield-dead short is bad

yotsuya:
GrantSpain-

Thanks. I did try one thing tonight- I read Ken Layton's excellent writeup on repairing these monitors. One suggestion called for replacing one of the resistors. I had a spare of the type he suggested replacing, so I did- but nothing changed. I'll test the HOT next time it's set up. I take it I put one end of my multimeter to the center leg (say, the red one, and the other end (the black) on the actual heatshield? If I do this, and I get nothing coming up on the meter, this means the HOT is bad?

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