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Screen of 25K7197 CRT is flooded with red
Question from Scott: Hi Tim,
I’ve enjoyed watching your videos and am happy to report that I followed your CRT discharging tip and survived.
Tim, I’m sorry to bother you about this. I’ve been trying to get answers to my problem with my 25K7197 CRT from the arcade museum forum, but all I’m getting is “probably a loose wire or cold solder connection” as help. I appreciate them trying to help me, but I need something more specific and a process to narrow down what’s bad. You are my last resort — really, because there are no arcade repair technicians on this island in Hawaii. I hope you can help, and I’ll be willing to pay you for your time or buy one of your products.
The problem is that I turned a couple of the pots on the neck board of my 25K7197 CRT and the colors got all out of whack, badly. Anything red faded into the background, and the black background got a dark red.
If I bang on the side of the arcade cabinet, the screen flickers a bit and you can see the colors come on correctly for a moment. Once in a while it will “lock” on the correct colors until you bump the arcade slightly.
Everything was fine until I turned a few pots on the neck board.
This picture of Donkey Kong should explain my problem. You can see the red girders faintly, but they blend into the dark red background (which should be black). My camera actually makes the screen appear redder than it really is, it’s a lot darker red, almost black, but anything with red in it “disappears”.
Thanks and Aloha,
Scott
1 answer
Response from Jonathan: Scott,
The guys on the arcade museum forum are probably right. This is more than likely related to a cold solder connection somewhere on your chassis. The “flicker” you are experiencing is a good indication of this. Of course, you’re probably looking at your chassis and thinking “There are a lot of solder connections on here, which ones am I looking for?” Good news is that we can probably point you down the right path.
There are three transistors located on the main board which should be labeled Q1, Q2 and Q3 and three on the neck board which should be labeled Q201, Q202 and Q203. These transistors control the colors. Try refreshing the solder on these parts and see if it makes a difference. If it doesn’t, then you might need to check out the chip located at label IC1. You can also try refreshing the solder on the potentiometers on the neck board that control the colors. Keep in mind that if refreshing the solder on these parts doesn’t help then you might need to replace them.
Hope that helps. Don’t worry about paying us for our time but if you would like to buy some of our DVDs from our online store we would appreciate it. Also, we would be happy to come out to Hawaii and help you with your issues in person if you didn’t mind paying a for our flight and expertise! 😉 Thank you for your question and good luck with your repair.
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