So I had a sega 16b pcb as part of an untested joblot off Mozie then bought the 16b multi off him as well since I didn't have any rom boards for the PCB.
It worked but with colour issues:
Aurail was looking particularly poorly:
But all the games had wrong colours in some way or other.
There were lots of fujitsu on the main PCB so I expected an easy fix but because of the way the rom board fits to the main board using the slice on most of the PCB was out.
So I piggybacked the fujitsu chips with known workers but none of them made any difference.
Cue lots of work with the oscilloscope on the back of the PCB where I could check the chips without the rom board stopping me but I could find no missing signals.
I started to suspect it could be a custom issue but I decided to see if I could see what parts of the main board handled colours and found if I shorted data lines on the two 2015 ram chips at J9 and J10 I found the good colours started to look corrupt as well so I took the plunge and replaced those ram chips.
And that fixed it. All colours good now.
It worked but with colour issues:
Aurail was looking particularly poorly:
But all the games had wrong colours in some way or other.
There were lots of fujitsu on the main PCB so I expected an easy fix but because of the way the rom board fits to the main board using the slice on most of the PCB was out.
So I piggybacked the fujitsu chips with known workers but none of them made any difference.
Cue lots of work with the oscilloscope on the back of the PCB where I could check the chips without the rom board stopping me but I could find no missing signals.
I started to suspect it could be a custom issue but I decided to see if I could see what parts of the main board handled colours and found if I shorted data lines on the two 2015 ram chips at J9 and J10 I found the good colours started to look corrupt as well so I took the plunge and replaced those ram chips.
And that fixed it. All colours good now.
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