I couldn’t really believe it when this fixed my scrolling issue as well. I spent time over the course of the next few days looking into this but found nothing.Įventually I got sick of looking at the washed out colours on screen and replaced IC90 to fix the last of the colour issues. A lot of work time and effort for nothing. I found nothing wrong so removed the PC080SN custom and replaced it with the spare but it made absolutely no difference. I didn’t enjoy replacing that IC so I started checking around to see if the scrolling issue could lie somewhere else.
Replacing this brought my sprites back but the scrolling issue was still present. Paulcan69 sent me a scrapper PCB so I could rob the customs off it if needed so I started out by replacing the PC0900J. The sprite and scrolling issue worried me because these areas are related to the PC080SN and PC0900J custom chips. Stupidly I chose to ignore the colour issue and concentrate on the other two (I will get back to this later). Other issues in-game showed me all the sprites were missing and the screen doesn’t scroll when entering a game. Replacing this gave me perfect results on the colour test screen in test mode but dull colours in game. Probing these revealed stuck bits on IC78. There are two 74LS245’s attached to the data lines of the colour RAM at location IC78 & IC90. Now I got a running game but the colours were messed up
Probing the data lines of the screen RAM show pretty much all of them across two RAM chips were dead. Now on boot up I got a screen seemingly running game but all the screen was garbage. All ROM’s checked out fine in the programmer and seeing nothing else obvious I removed the work RAM both of which failed. Yet another Operation Wolf repair and this one gave me trouble.įirst test we had watchdogging.
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