No so much of a fix log as another cautionary tale from me.
I'm fixing a few boards for Vamino and one was a konami Mikie.
When I tried it it wasn't outputting anything,no sync or video but there was activity around the CPU so after tracing the sync backwards I found a faulty 74LS368 at D14 on the video board.
Removed it but only had 40H368 in my spares so used one of them and got video but it was cycling garbage:
At first I thought the code wasn't running so spent a while checking the CPU,roms plus all the bus chips and other parts of the main CPU system but to no avail.
Then I remembered that Vamino told me it was booting to a rom or ram error when he tried it and since most of the boards he gave me were Konami I knew that these boards reboot a short while after showing an error message so I figured it was maybe constantly booting to an error but corrupt video was stopping me from seeing it.
Long story short after about 4 days of looking around the video board it ended up being the 40H368 at D14 I had used.
Since I could see graphics and text on the screen I figured the timing must be correct but taking a 74LS368 off a scrap board and putting it in this one fixed it and it now plays fine.
You live and learn.....
I'm fixing a few boards for Vamino and one was a konami Mikie.
When I tried it it wasn't outputting anything,no sync or video but there was activity around the CPU so after tracing the sync backwards I found a faulty 74LS368 at D14 on the video board.
Removed it but only had 40H368 in my spares so used one of them and got video but it was cycling garbage:
At first I thought the code wasn't running so spent a while checking the CPU,roms plus all the bus chips and other parts of the main CPU system but to no avail.
Then I remembered that Vamino told me it was booting to a rom or ram error when he tried it and since most of the boards he gave me were Konami I knew that these boards reboot a short while after showing an error message so I figured it was maybe constantly booting to an error but corrupt video was stopping me from seeing it.
Long story short after about 4 days of looking around the video board it ended up being the 40H368 at D14 I had used.
Since I could see graphics and text on the screen I figured the timing must be correct but taking a 74LS368 off a scrap board and putting it in this one fixed it and it now plays fine.
You live and learn.....
