Taito Sky Shark Board Repair Help

[r67055]

Hi there.
I would like to start repairing a Sky Shark board.
I want to ask for help. I haven't met a Taito board yet.
Black screen after switching on...
I read all Eproms.
All flawless.
I checked the operation of the 28Mhz quartz and found it to be good.
The clock signal is received by the 68K Cpu.
made it this far. What should I look into next?
Thanks

 

[ekorz]

Admittedly my luck is low if it doesn’t boot, but two more easy things to check…

Reset signal operation on cpu’s reset pin (and accompanying reset circuit)

Ram connected to the main program roms (i.e. work ram) enablement lines and probing other data/address lines.

 

[XtraSmiley]

I've had two boards with this problem now.

https://www.arcade-projects.com/threads/help-with-this-hishouzame-pcb.16716/

 

[XtraSmiley]

And this:

View: https://www.youtube.com/watch?v=IsSb0gXmLYo

 

[r67055]

I checked the 68K reset pin. It is at high level. So it's not in permanent reset.

Experience: The C-01 (GXC) costum chip shown in the picture is heating up. Not like if it was short-circuited. The other Chips are not hot.
I think that C-01 could be the cause of the error.
The repro chip is not cheap, 70 USD plus TMS32010 chip 40usd __110usd .this pcb is not worth that much money
I would spend money on it. if that's not the problem, what do I do with the Repro Chip?

 

[XtraSmiley]

I checked the 68K reset pin. It is at high level. So it's not in permanent reset.

Experience: The C-01 (GXC) costum chip shown in the picture is heating up. Not like if it was short-circuited. The other Chips are not hot.
I think that C-01 could be the cause of the error.
The repro chip is not cheap, 70 USD plus TMS32010 chip 40usd __110usd .this pcb is not worth that much money
I would spend money on it. if that's not the problem, what do I do with the Repro Chip?

Yes, the game is only worth $100-150. Tough position to be in.

Do you know someone close who has the game, you could swap the chip to test.

Otherwise, sell the board as non-working and buy a working one.

 

[r67055]

Yes.
Thank you very much for your help everyone!!!

 

[Blio Seri]

I checked the 68K reset pin. It is at high level. So it's not in permanent reset.

Experience: The C-01 (GXC) costum chip shown in the picture is heating up. Not like if it was short-circuited. The other Chips are not hot.
I think that C-01 could be the cause of the error.
The repro chip is not cheap, 70 USD plus TMS32010 chip 40usd __110usd .this pcb is not worth that much money
I would spend money on it. if that's not the problem, what do I do with the Repro Chip?

To be honest it doesn't look that complicated (TMS32010 + external ROM?).
I'd try to make my own repro, you'd learn a tad in the process, and if ultimately it becomes open source that would be great for the community.

 

[r67055]

Yes, the game is only worth $100-150. Tough position to be in.

Do you know someone close who has the game, you could swap the chip to test.

Otherwise, sell the board as non-working and buy a working one.

I can get a superman sheet as a trial part. does this have a C-01 chip?
I don't think it has C-01, but you must have seen more pcbs.

 

[r67055]

the repro part arrived, it doesn't want to work. Black image.

 

[r67055]

I didn't feel good when I turned it on and it didn't work. I started researching again. I read the main cpu eproms. I burned it again. then I took out the rams and checked them. 2 RAM ok. I noticed that the AV screen is wavy. there is something wrong with the output signal. out of curiosity, I burned the Flaying Shark rom US 1 content (b02_17-1, b02_18-1) then the AV text was displayed correctly on the screen. This indicates that the rom content is not the fault. I don't know where to go? can other L-02 (GLX-02) cause the error?

 

[r67055]

maybe i didn't check things properly...
I checked the maincpu eproms (17-18 ). Logic probe shows no signal on many pins. I checked the 20 pin, it shows High level. There is no movement on the data legs. the 17-18 maincpu eprom does not start. What could be the reason?

 

[r67055]

I powered up the pcb again.
I noticed that the C-01 costum Chip starts to get hot after 5 minutes. Maybe there is a mistake there?