Major Havoc - Garbage Screen

advans13

Requested Self-Ban
Joined
Feb 26, 2008
Messages
7,378
Reaction score
5,649
Location
Portland, Oregon
so i received my conversion board from billtronix (awesome piece btw) , and took out my space duel pcb to throw the mh pcb in to test. i bought it "untested" so i was assuming it would be dead, but in fact it did boot.

here is some of the screens that i was greeted too. i cannot identify any errors on self-test, as i cannot read them. i did swap the avg from my working space duel pcb, and vice versa...both had no effect, but the mh avg did play space duel fine. all socketed chips were cleaned thoroughly.

the game does play, and all the sounds work. it is just a garbled mess.
 

Attachments

  • mh_tests.jpg
    mh_tests.jpg
    112.3 KB · Views: 107
  • mh_tests2.jpg
    mh_tests2.jpg
    112 KB · Views: 82
Bad DAC on video output? Y looks good, X looks corrupted.

Try swapping DACs at 11D and 11A/B to see if it changes anything.

To other readers, AVG substitution has already been made with no change in screen.


Possibly bad vector data shifter 74LS194 at 8A, 8B, 8C ? Swapping these amongst themselves should not change anything but if it does, one is bad.



Bill Boucher
 
Last edited:
Done some probing but nothing high level. Think I will send this off to someone. So who's would that be? Is there anyone on the west coast?

I would tackle this, but it is too high dollar of a board for me to mess with any further.

Chips at 8a,b, and c probed and look normal. The two chips at 11a and d. Am6012's pin 16 when probed kills display and the spot killer goes on. The lower am6012 a the same pin collapses the image to a vertical line down center of screen. That is about all I've messed with.
 
Do you have activity on pins 2 thru 11 of the DACs? If 8A thru 8C look good it could be 9A, 9B or 9C. The effect of loading on pin 16 seems odd but isn't really.
 
I've been slacking on this. However I have ordered some parts.

I was looking at the two jumper points, and was wondering if everyone's look like below. Note: top two pins in pic. ImageUploadedByTapatalk1355620767.714469.jpg
 
I've been slacking on this. However I have ordered some parts.

I was looking at the two jumper points, and was wondering if everyone's look like below. Note: top two pins in pic. View attachment 128520

I don't get it. What do you mean "look like"?
 

Attachments

  • IMAG1652.jpg
    IMAG1652.jpg
    108.8 KB · Views: 20
  • IMAG1653.jpg
    IMAG1653.jpg
    102 KB · Views: 18
This is my MH PCB in my Tempest cab......it is working with no issues....hope this helps.

034_zps2c312572.jpg


033_zps52331fdd.jpg


DSCF1480_zpse1b103c3.jpg
 
So I found this between 9a and 9b. Not sure if you can make it out. But, I will highlight it with pic software tomorrow.ImageUploadedByTapatalk1355638338.338408.jpg
It appears that one trace is whack, at one solder point there in the middle of the chips are showing continuity to an adjacent trace.
 
Back
Top Bottom