MK1 Y-Unit U99 Issue

[MK4Arcade]

Hello,

I recently won a MK1 PCB off of eBay and it needed some repairs. I'm at that point where all of the ROMs check bad, except U89 and U105 in the boot screen. I restarted the test and now it marks U99 as bad and the graphics are all blurry. Can the bad ROMs be causing the boot screen to show U99 as bad?

 

[CoolFox]

Afaik no....make sure there are no cut traces, take the U99 out and make sure none of the pins are bent. If everything checks out you may have a bad u99.

 

[MK4Arcade]

I will definitely try that...I checked continuity and everything seems to check out. It's weird how it marked it as good before (see link).

https://www.dropbox.com/s/8ez45bcz4klbpeh/Screenshot_20210611-204315~2.png?dl=0

 

[CoolFox]

That is a little bit odd, but all of the roms being bad is a little suspect of a bad U99 or U36. However I did find bent pins in my U99 at one time, so it's always a possibility.

 

[MK4Arcade]

I agree...I will try that and see if it works out. Thank you!

 

[stj]

dump all the roms and compare them to mame sets

 

[MK4Arcade]

I had ordered an EPROM programmer so I'll update this thread once I receive that.