Toplan Out Zone Pcb

[r67055]

Hello!
Can I ask you for help?
There is a Video Error Pcb. Can you tell me which is the Video ram based on the schematic?

shematic : https://www.jammarcade.net/files/Sc...x0eNQQ_ruL3rLNlRcNe-hTUnVPWF-d1ZCCUBjS5JfMUHA

Thanks!

 

[cwispy]

The video ram is going to be 14J and 14K, but its not a certain that they are going to be the problem. It could be any one of the ic's in the area depending upon the actual fault. It may not even be in the video section at all.

 

[r67055]

The video ram is going to be 14J and 14K, but its not a certain that they are going to be the problem. It could be any one of the ic's in the area depending upon the actual fault. It may not even be in the video section at all.

thank you very much for writing to me.
the error has changed over time.
An object ram error has occurred.

 

[cwispy]

Looking at the circuit again, the rams at locations 14J and 14K appear to be colour rams. Unfortunately I am not familiar with that particular pcb. There is a lot of srams on that board according to the circuit. My best guess would be to start around the rams at 16A.

 

[r67055]

Looking at the circuit again, the rams at locations 14J and 14K appear to be colour rams. Unfortunately I am not familiar with that particular pcb. There is a lot of srams on that board according to the circuit. My best guess would be to start around the rams at 16A.

I checked all 6264 rams D0-D7 pins are connected to the FCB costum chip. I checked the 6264 rams A0-A12 pins are connected to several logic chips. I checked A17, 74ALS174 Ic which is faulty. I replaced it, but I only have 74ls174 ic at home. no changes were made, the error remained. I know that the ALS has a faster speed than the LS. I noticed in the schematic that pin 1 (CLR) is connected to vcc, which the pcb is not. I connected it but unfortunately nothing changed.

 

[cwispy]

Well done finding the faulty 74ALS174. I would be very surprised if a 74LS174 wouldn't work in its place, as these boards generally do not run anywhere near the speed that an LS is capable of.
All I can suggest is to continue doing what your doing to find the remaining faults. Good luck!

 

[r67055]

Well done finding the faulty 74ALS174. I would be very surprised if a 74LS174 wouldn't work in its place, as these boards generally do not run anywhere near the speed that an LS is capable of.
All I can suggest is to continue doing what your doing to find the remaining faults. Good luck!

thank you for the trust.
I don't understand why they didn't put 74LS174 in it and why they chose the faster ALS...
Is there a way to exclude Ram groups?
Which refers to Obiject Ram?
For example, in group 62256, I cause the A0-A14 error by connecting 2 lines (short circuit), then the screen errors can be seen.
Does this mean that the 64256 ram group is not the Obiject rams?

 

[cwispy]

Without knowing the boards better I cant say for certain that those rams do not have anything to do with the objects, but it would appear that they do not based on your image.

 

[r67055]

Without knowing the boards better I cant say for certain that those rams do not have anything to do with the objects, but it would appear that they do not based on your image.

I also think that the rams are not the fault in this pcb. my fear is that costum Chips can also cause the error. I would like to exclude all ram groups. Unfortunately, I don't know how to exclude groups for sure.

 

[cwispy]

If those boards use the same or similar customs as the Snow Bros boards, then a faulty custom ic would not be surprising at all. Sorry I can not really be more help.