Feb 092018
 

Got always from Portugal this Alien PCB:

As often happens on this hardware the sprites had jailbars thru:

Board uses 4Mbit MASK ROMs to store GFX (sprites and background) data that are quite prone to failure.I launched a MASK ROM check that reported a bad device @K8:

I removed it and my programmer warned me about pin 13 (data line D0).I tried the dump in MAME and I could reproduce the issue :

I replaced the MASK ROM with an equivalent 27C400 EPROM :

This fixed issue and board completely.End of job.

 Posted by at 10:56 am

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