27-11-2025, 05:48 PM
There are special "Coreboard Riser" PCBs you can use to lift the top "Core" Board out of the way so you can access all the signals. I have heard of people using a bunch of dupont male to female cables as a substitute, but I can't imagine they would be great for signal integrity.
Someone here might have a spare set of the PCBs for sale. I'm not sure if the gerbers are out there. If they're not, I can probably remake them pretty easily. I have some ideas on how to make a "better" version with tap points for key signals.
I know I found my set invaluable for tracking down an issue with the reset.
The reset signal comes out on the edge connectors that go up to the Core Board, so you can check it there. Pin 18 of the RHS X5 connector. I think Pin 12
Also, if you haven't yet grabbed them, there are schematics and board layouts for all the various models of main board and core board which I found invaluable when tracking through the issues I had seen. They're in the repository.
Depending on what tools you have access to, there's other things we can do. I found an oscilloscope and an EPROM burner to be genuinely useful tools. If you don't have them, see if there's a "Maker" space nearby that you can join and borrow them from. I've got a RAM Test ROM burned that helped me pin down some bad 4164 chips on my DRAM Core board. (Also in the repository)
If you do have a scope, check to see if there's a video signal coming out of the composite plug on your cable. It could just be your output device is playing up. (Ask me how I know about that particular issue :-D )
Hopefully we can help you get it working sooner rather than later.
Cheers!
John
Someone here might have a spare set of the PCBs for sale. I'm not sure if the gerbers are out there. If they're not, I can probably remake them pretty easily. I have some ideas on how to make a "better" version with tap points for key signals.
I know I found my set invaluable for tracking down an issue with the reset.
The reset signal comes out on the edge connectors that go up to the Core Board, so you can check it there. Pin 18 of the RHS X5 connector. I think Pin 12
Also, if you haven't yet grabbed them, there are schematics and board layouts for all the various models of main board and core board which I found invaluable when tracking through the issues I had seen. They're in the repository.
Depending on what tools you have access to, there's other things we can do. I found an oscilloscope and an EPROM burner to be genuinely useful tools. If you don't have them, see if there's a "Maker" space nearby that you can join and borrow them from. I've got a RAM Test ROM burned that helped me pin down some bad 4164 chips on my DRAM Core board. (Also in the repository)
If you do have a scope, check to see if there's a video signal coming out of the composite plug on your cable. It could just be your output device is playing up. (Ask me how I know about that particular issue :-D )
Hopefully we can help you get it working sooner rather than later.
Cheers!
John
John "CheshireNoir" Parker
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One Dark Little Kitten
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One Dark Little Kitten