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Author Topic: WG 27K7401 - No Picture  (Read 3007 times)

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Terminatedrone

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WG 27K7401 - No Picture
« on: February 03, 2009, 10:42:27 pm »
Hi guys,

I have a Time Crisis 2 machine that has two 27K7401s in it. One of them works fine, but the other one is having serious issues.

I've tested the cables, the game, and the setup and am sure that the problem is with the one monitor.

- It has no picture. No colors (except for a faint blue glow).
- There is an orange glow in the neck (good sign).
- If I turn the screen up, or adjust the Green and Red drive on the neck board I can hear clicking and the screen flickers (white).
    - When doing this the clicking and flicker is intermittent and only lasts continually if I turn them way up (more than half way).
- The white light displayed on the screen definitely is biased towards the center (vertically) but its not a bright horizontal line (like vertical collapse). It sort of looks like two moderately bright lines about four inches apart, but with light emitting from between and around the lines as well.

I'm looking for some help to troubleshoot this.
What would really help is if someone could guide me through the troubleshooting process, which components to test, how to test them and what the reading should be.

While I have the monitors out, I would also like to do cap kits. I'm not sure which cap kits to get from Bob Roberts though.

I'm stuck between:

K7400/K7500 High Temp Cap Kit - I don't know what a "high temp" cap kit is.
U2000 25" color - I believe the K7400 is the replacement for the U2000, but this kit is labled for 25" (I don't know if that means its different from the kit for 27").

I appreciate the help.

SirPeale

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Re: WG 27K7401 - No Picture
« Reply #1 on: February 03, 2009, 11:02:42 pm »
K7400s are notorious for being particularly sensitive to B+.  Find the B+ pot, and nudge it down, just a hair.  I mean the tiniest of tiny bits.  If it doesn't work the first time, try again.  If it doesn't work the second time...well, we'll burn that bridge when we come to it.

Terminatedrone

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Re: WG 27K7401 - No Picture
« Reply #2 on: February 03, 2009, 11:05:28 pm »
Peale,

I don't mean to sound like an idiot... but do I nudge it down while the monitor is running? Or do I nudge it down and then turn the monitor back on?

Thanks for the quick response.

grantspain

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Re: WG 27K7401 - No Picture
« Reply #3 on: February 04, 2009, 02:58:24 am »
i guess you have faulted this to the monitor,from the first post it sound almost like a game board problem-but i guess you have swapped those to prove that
a photo of what you get would help.
http://www.wellsgardner.com/pdf/Repair/K7400_25_inch.pdf

Terminatedrone

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Re: WG 27K7401 - No Picture
« Reply #4 on: February 05, 2009, 11:14:58 pm »
Well, the problem gets worse. Because of what I presume was a grounding issue, cap 803 went up in smoke.
I'm not sure what else went with it, so this board needs to go in for repairs.

Back to the cap kit though, does anyone know which kit the 27" K7400 needs?