Jan 082016
 

Got this Taito Megablast for a repair:

Mebaglast_PCB

When I powered it up, I was greeted by a solid black screen, /RESET and /HALT on main 68000 CPU were stuck high.A visual inspection revealed that JAMMA connector was oxidized.Once cleaned it, the board booted:

issues

As you can see both tiles and sprites had sever issues, besided the sound was all garbled and scratchy:

So, for first I went to dump the devices containing tiles/sprites (three 40 pin MASK ROMs 27C400 compatible) and audio samples (two 32 pin MASK ROMs 27C040 compatible) and dumps were not matching the MAME ROM set for the ones @IC32 (sprite data), IC58 (tiles data) and IC29-IC30 (audio samples data) :

DATA_location

Loading my dumps in MAME I could reproduce the issues more or less accurately:

Replacing these bad MASK ROMs with the equivalent EPROMs fixed completely the game.

fixed

 Posted by at 4:51 pm

  One Response to “Megablast repair log”

  1. That game always sounded interesting to me. Glad you got it fixed !

    These 42pins mask roms present on Taito F1/F2 boards seems to be fragile. I had to replace a bad one on a Thunder Fox as well.