Missile Command Screen 4X to 8X size!

JoeB1355

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I'm working on a Missile Command and got it to finally pass self test, but now I have this strange video problem

The screen is blow up for 4X or 8X size like its zoomed in in both vertical and horizontal. I tried 2 different monitors just to be sure!. It seems to be synced fine as well although maybe its just wrong.

Anyone seen this one before? have a clue where to start looking?

pic of self test screen below
 
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I've seen that before. I *think* it's either N2 or P7. It could also be a bad L6 and/or socket. I would look at those three in that order - N2, P7, L6.

It's funny, I've seen a similar issue where all the graphics are stretched out 4x their size and it looks like you're playing MC on a 2600! :D
 
N2 and P7 didn't do it. I put new sockets for the sound chip and cpu as well. They were bad.

I put a new socket in for L6 too. No L6 chip to swap. Gotta find another board.

No change it still works as much as it did before -- so at least I didn't break it any more (other than my CPU socket debacle -- which took me a while to repair)!

Any other suggestions?
 
N2 and P7 didn't do it. I put new sockets for the sound chip and cpu as well. They were bad.

I put a new socket in for L6 too. No L6 chip to swap. Gotta find another board.

No change it still works as much as it did before -- so at least I didn't break it any more (other than my CPU socket debacle -- which took me a while to repair)!

Any other suggestions?

Maybe there is still something going on with the sync.

Here is a link to a video

http://youtu.be/mHcdn-Z4Fwo
 
Further digging around on suggestions from bitsilcer and getting me off thinking the sync was bad I could then dig further.

Its was bad MADSEL! Traced through the schematics tracking the signal. It was a bad R4. The pulses go in but they don't come out! I pulled a chip off a broken crystal castles board and now I'm in business.

You can see in my video I alos did my first TV tube swap (yoke and all!). The colors were off then but I moved the yoke back a hair and now the picture is good! Small bit of horizontal folder over didn't adjust yet and I think the flyback may be going bad as it occasionally is making noises -- picture is fine though!

All in All a good day!
 
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