Sep 202015
 

I got this Major Title 2 PCB for cheap from ‘Smitdogg’ of MAME team:

Major Title 2_PCBX i

He said me board had some GFX issues.Actually when I powered it up I got no sprites at all:

no_sprites

For first I checked the sprites EPROMs with my logic probe and found no activity on all pins.These four sprites MASK ROMs on video board are addressed by the ASIC “GA22” on CPU board :

NANAO_GA22

I probed it and all its pins were silent too.I tried to reflow it without luck, sprites were still absent.Then, looking at the board, I noticed an open jumper ‘J3’ right hear the GA22 ASIC:

J3_open_jumper

Looking at other M92 CPU boards I could see that this jumper was always closed to position ‘B’ (so with central and right pins shorted together).So I did it on my board too:

J3_closed_jumper

and sprites were magically restored!

Now the technical explanation.The jumper is actually for selecting which clock signal must be delivered to the sprites generator ASIC “GA22”.If closed in ‘B’ position, ASIC will receive a clock signal of 26.6666 Mhz (which is the correct value for most of M92 games) :

26.66666_signal

If closed in ‘W’ postition, the ASIC will get a 18.000MHz signal (no sprites with this configuration) :

18.000MHz_signal

Last issue to fix was some audio background noise:

I quickly traced it to a missing 47uF 16V electrolytic capacitor @C213 in analog sound section:

missing_C213_capacitor

End of job.

 Posted by at 10:17 pm

  4 Responses to “Major Title 2 repair log”

  1. i hope you know that since you changed the website layout, it has not worked on a lot of browsers – the text goes off screen.
    including what i’m typing now.

  2. Personally I have no problem with Chrome and Explorer.Please, let us know your setup.Thanks.

  3. Like always a great repair log my dear italian arcade hero! 🙂
    I had like 2 or 3 M92 board in the past with the same problem and fix it also adding the missing jumper.
    Easy and fast fix to revive a lot of great games available on Irems M92 platform.

    Keep up the good work Fabrizio!