Zaxxon, Horizontal (well, really they are "vertical" on a rotated crt) black lines.

RobMcRaf

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Zaxxon, Horizontal (well, really they are "vertical" on a rotated crt) black lines.

The first all-original unconverted cab I got after moving to Virginia 14 years ago was this exact Zaxxon. Sold it about 3-4 years back to a local collector.

His son just brought it back to me. I paid him about what he paid me.

Hadn't been on in a year and now has these stripes. It's not a monitor issue. (Yes, I see the curl. Will deal with that.)

They are spaced evenly but they don't affect any of lines of text (or numbers) on the game or high score table screen. In other words, none of the words/numbers in the game that are from the boards character set have the lines through them.

Before I start troubleshooting, was hoping that someone could just say "Hey, I know that problem, it's chip XXXX at location XXXX".

Just hoping to cut the troubleshooting time! Thanks.
 

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I'll see what info I get from the self-tests when I get home. Thanks. Will be a while before getting really into it since I need to make a Jamma adapter to play with it outside of the cabinet.
 
Looking at the regularity of the fault, I'd have a look at the horizontal count signal, and counting how many black lines there are, possibly 8H signal and where it goes onwards
 
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Looking at the regularity of the fault, I'd have a look at the horizontal count signal, and counting how many black lines there are, possibly 8H signal and where it goes onwards

K, thanks, and I guess more accurately I could have titled the post 'vertical' black lines :)
 
It is every 8th line, but 8H doesn't really have much to do with it.

Thanks for ruling that out.

In which case, as it looks to be both background and sprite data affected (suggesting background & sprite circuits themselves are ok) should the OP be looking at where they're muxed by the 157's (U39/U59) and work through to just before it becomes RGB?
 
Thanks for ruling that out.

In which case, as it looks to be both background and sprite data affected (suggesting background & sprite circuits themselves are ok) should the OP be looking at where they're muxed by the 157's (U39/U59) and work through to just before it becomes RGB?

Something's got priority over both bg and sprites and is blanking them out, so well past U39/59 in the chain.... :)
 
OK, good starting point. Thanks. I had to order a couple 44/22 edge connectors to make an adapter so will be a couple weeks until I'm picking this back up. Really great schematics on this PCB.
 
I've got Zaxxon to JAMMA adapters in stock :)

Thanks, but I've just sent out for a 10-pack of them. They come in handy and I was surprised when I opened the drawer and there were none of that size. Must've used them up making stuff. :)
 
Yeah, I'm just about out too... so I ordered 200 :)

Well, sir, you have me there!

Seriously, thanks to you guys for taking a couple minutes to start me off in the right direction. Been a while since I picked up the logic probe. the O-Scope has a thick layer of dust on it. Spent the last 2 years in a hellish nightmare of rotten games trying to save any parts that were salvageable.
 
Additional info: after about 30 mins of being on, the vertical lines went away and the screen curl decreased a tiny bit. Looks good enough to play. Not what I want long-term, but for $80, I can't argue. :)
 
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