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Help Repair NMK PCB (Bio Ship Paladin)

R

_rm_

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Have this board that doesn't boot, onlyu shows screen with green garbage.

Checked the basics and found no Reset signal on the MC68000. Tried to trace back the signal but seem like the logic on the 74LS on the relevant area are ok. Even dessoldered a couple to check outside the circuit and and they were fine.

Running out of ideas, does anyone with experience on these type of boards can give me any hint? Or do you know what are the relevant and expected signals to check on the NMK 004 Custom Chip? Starting to suspect that guy...

Any help will be much appreciated.

Thanks in advance and kind regards
 
004 is quite solid, but the 6116 ram with it is a common fail.
the reset section on these is very fussy, i have a macross somewhere that only boots occasionally and never tracked down the fault...
 
I've spent the last few days with this board and it never booted, consistently showing the same Green screen. So at least is not some fussy problem that happens sometimes...
Will double check those rams and try to be sure.

Many thanks for your input
 
Hammy said:
I have a test rom for the normal boards, (it test ram, nmk004 comms etc) but it won't work on strahl or bio ship due to the extra chipset.
Maybe i can mod it to run on that board fairly easily, but i'm low on time right now.
Click to expand...
Wow, that would bem amazing, but I can wait the PCB is not going anywhere 😅

Took the time to check the 6116 rams yesterday and they all look fine on the scope. Even piggybacked them just in case.
 
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