WG7400 confusion

LordRyGuy

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I'm going to try to make this as easy to read as possible.... I got a 7400 recently that works... I just recapped it.. It works well, looks perfect. But in the process of troubleshooting the neckboard I found something interesting... Im going to refer to this chassis as board "A" .. I took neckboard "A" and put it in my blitz cab with a U5000 in it (same neck board) and it was a lot brighter than my neckboard normally in blitz. I had to turn the brightness down a lot. Then I took the entire chassis "A" and put it in my MK4 cab and it looked great.. Here's the strange part, I took the neckboard form the chassis that is normally in MK4 (that works and looks perfect) and connected it to deflection board A and the screen is almost completely void of color.. It looks pretty much black and white...

So whats the deal here? Is it possible that this chassis was modded? Or could there be an issue with the deflection board that you don't notice when the neck board is connected because that neck board happens to blast color and brightness moreso than a normal 7400 neck board? I want to get to the bottom of it but I'm not sure where to start. I mean, yes I have a good working chassis but it came from a monitor that had a bad tube. It's probably a long shot but could there be a mod done to this board that damaged the tube over time? I unfortunately do not have any other info reguarding this monitors past. I just did a monitor swap for a friend and I took this chassis as payment (that and my friend has zero use for it now).
 
If you have two boards that look perfect, why in the hell are you swapping parts around and adjusting and messing with things? All this shit is fragile as hell, if it works good leave it the hell alone.
 
It was something I noticed before I repaired the board when I was swapping known good parts to see if certain issues were coming from the neck board or the deflection.
 
If you pay attention to detail, you'll notice that the two neckboards are probably not exactly the same. The dual-res U5000 neckboard has a transistor and cap near the IC that the standard-res K7400 neckboard probably doesn't. While the board is the same between the 4 models, they aren't always populated the same way. That's why they often have different letter designators in the identification number on rhe neckboard label...
 
Yeah that was one thing I definitly noticed.. This neck board is also missing 3 resistors that my other neck boards have as well.. I just marked this chassis as good and stored it in the closet. I'm not going to mess with it.
 
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