Need help with a Mario Bros coversion - white screen
hey guys,
I bought a DKJR with MB conversion and I'm having trouble figuring out if the board is bad or if it's something else. I get the white screen so many others get and I've searched and tried all suggestions but still no luck.
Right now I'm not getting sound or anything so I can't say if it's playing blind but I am planning to change out the sound board and amp with a known working one to see. And it's a known working monitor with new flyback and cap kit, B+ is dead on 108v
Now all my voltages from the PS to the filter board are good, the only thing I've noticed is that the power from the filter board to the PCB is ok except for the video feeds, they all drop to about 4 volts, everything else stays the same. I've also checked the monitor cable and power is right about 4 volts for R,G,B and sync. I did put in a working PS from my DK cab and had someone mention that being an issue but after checking the #'s the MB is a 7B and the DK is a 7A, should be the same outputs from everything I've read.
I have tried swapping the Z80 chip, removed and cleaned all the chips (sorry, EPROMS I think they're called, not too savvy in this dept), cleaned the board, etc. I have not tested every circuit for continuity but did a visual inspection and can't see any scratches, bad solder joints, etc. I also plugged the PCB into the adapter bypassing the filter board, same white screen.
Any ideas, tips, advice???? I'm still learning and not great with much beyond checking voltage, continuity and soldering. I do not have an EPROM reador or a logic probe or really any idea how to use them but am willing to learn. Thanks!
hey guys,
I bought a DKJR with MB conversion and I'm having trouble figuring out if the board is bad or if it's something else. I get the white screen so many others get and I've searched and tried all suggestions but still no luck.
Right now I'm not getting sound or anything so I can't say if it's playing blind but I am planning to change out the sound board and amp with a known working one to see. And it's a known working monitor with new flyback and cap kit, B+ is dead on 108v
Now all my voltages from the PS to the filter board are good, the only thing I've noticed is that the power from the filter board to the PCB is ok except for the video feeds, they all drop to about 4 volts, everything else stays the same. I've also checked the monitor cable and power is right about 4 volts for R,G,B and sync. I did put in a working PS from my DK cab and had someone mention that being an issue but after checking the #'s the MB is a 7B and the DK is a 7A, should be the same outputs from everything I've read.
I have tried swapping the Z80 chip, removed and cleaned all the chips (sorry, EPROMS I think they're called, not too savvy in this dept), cleaned the board, etc. I have not tested every circuit for continuity but did a visual inspection and can't see any scratches, bad solder joints, etc. I also plugged the PCB into the adapter bypassing the filter board, same white screen.
Any ideas, tips, advice???? I'm still learning and not great with much beyond checking voltage, continuity and soldering. I do not have an EPROM reador or a logic probe or really any idea how to use them but am willing to learn. Thanks!
