CPS2 No sprites

[yavuzg]

This is a non-corroded B board (Dungeons & Dragons: SOM - Japan). First problem was completely garbage screen but the sound, music was OK and game was blindly playable. I've checked the gfx ROMs with oscilloscope and found that the address lines of all the first column of gfx ROMs (i.e. 13,14,15,16) were stuck high.

Replaced the DL-1927 (CGA) and the video is now clean but still the sprites are missing. All the gfx ROMs now have activity on their address and data lines, according to my scope. Obviously this board had faced some sort of voltage problem which burned the DL-1927 partially. There is a big possibility that some other customs may have been partially burned too.

So my question is; If a CPS2 B-board has absolutely NO sprites (I mean, not garbage sprites but totally missing) what might be the reason?

Ah, almost forgot to mention that I've also tested the PCB with Raz's suicide tester ROM and all looks GOOD there. Also results of memory check on the test menu is all OK.

 

[kuze]

It definitely sounds like one of the other customs has gone bad. :-/

 

[yavuzg]

It definitely sounds like one of the other customs has gone bad. :-/

The million dollar question is; which one

The Object RAM is OK. they seem happily working on my scope and pass the tests. Could it be the DL-1827 (CIF) ? (which is right next to the object RAM)

I can replace that one with no time but I'm using an already dead board to salvage parts, meaning the salvage parts might be bad also...

 

[kuze]

It definitely sounds like one of the other customs has gone bad. :-/

The million dollar question is; which one
The Object RAM is OK. they seem happily working on my scope and pass the tests. Could it be the DL-1827 (CIF) ? (which is right next to the object RAM)

I can replace that one with no time but I'm using an already dead board to salvage parts, meaning the salvage parts might be bad also...

Indeed!

I don't think anyone has publicly posted what custom does what, but I could be wrong.

You might have to try swapping one custom over at a time and hoping that your salvage parts are good.

 

[yavuzg]

yeah I was hoping @l_oliveira would jump in for that question

I know (CGA) is for something like addressing of the graphics and (CGD) is for the data. I also know the SPA contains the 68000 and the encyption keys. MIF and CIF are totally unknown for me...

 

[l_oliveira]

Have you tried replacing the CIF IC? MIF is apparently some sort of bus arbitration controller for the CPU bus. I'd guess it means "Memory InterFace".

I believe CIF is the register frontend for the sprites hardware. The object RAM is connected to the CIF chip.

 

[yavuzg]

SOLVED...

While I was probing the data lines with my scope I noticed that the signal pattern was a bit weird. Although there is activity, didn't looked right. Then I've checked the DL-2027 (CGD) custom's legs, and some of them were generating that weird pattern...

I did have another D & D: SOM 100% working non-suicided B-board and took it out from the shelf and monitored the same pins. The signal shape was different...

I replaced the DL-2027 and now I have the sprites back and 100% working board...

 

[l_oliveira]

SOLVED...

While I was probing the data lines with my scope I noticed that the signal pattern was a bit weird. Although there is activity, didn't looked right. Then I've checked the DL-2027 (CGD) custom's legs, and some of them were generating that weird pattern...

I did have another D & D: SOM 100% working non-suicided B-board and took it out from the shelf and monitored the same pins. The signal shape was different...

I replaced the DL-2027 and now I have the sprites back and 100% working board...

Glad to hear you have it solved. Well, the fact that it was passing object ram tests reinforced the possibility of CIF being ok. But I have no idea how it connects to the hardware on the A board (SPB, DRC and the 1MB of EDO RAM buffer) which generates the sprites. Which means I would suspect faults could happen on the path between them or at the CIF outputs.

 

[yavuzg]

For future reference, this was the situation (after I replaced the DL-1927); Sprites were totally missing

And the signal I monitored on my scope at the certain data pins of the DL-2027. Look at the edges...

And this is the signal at the same pins on my other 100% board. Notice the difference...

After replacing DL-2027

 

[l_oliveira]

Probably a control pin bonding failed and it made a internal buffer stop working. You probably noticed that the graphics ROMs are arranged in 2x2 way. The board is capable of reading two or four of them at once. Scroll layers need two of them at once (half of a bank) and sprites need all four(full bank).