There's very little mention of this conversion online so I thought I share it here, the DK PCB has provisions to swap between negative/positive video and onboard/external sound amplification.
The DK PCB was normally paired up with a Sanyo EZ20 monitor which uses negative video and has an onboard sound amp.
If you want to plug a DK PCB into a Jamma cab you need a special Jamma adapter that inverts the video signal and amplifies the audio.
I'm repairing some boards for our Australian 'Kong Off' in November that need to be able to be plugged into both an original Nintendo cab as well as a standard Jamma cab.
Fortunately the PCB is designed to be able to do this and you just need to populate it with the missing components.
Below is what you need to do to mod a board.
There's two sections on the CPU board where there are a number of unpopulated component locations.
One is video and the other is sound.
Video section...
Sound section...
The yellow jumpers are where a 10 way DIP switch needs to be fitted to swap between outputs.
This is what it looks like when modded.
The video transistors should be 2SC1815's but they're not commonly available here so they have been substituted for 2N3904's, they have a different pinout so the centre and right legs (Collector-Base) need to be swapped around.
It uses an MB3712 amp which can be substituted with an MB3713 flipped around (reverse pinout).
The correct sized 10K volume pot is also not commonly available here so I made a small riser/adapter board to in a standard trimmer pot (a 24mm pot could be remotely mounted somewhere off the board if desired), VR3/VR3/VR5 adjust the video bias.
All the component values are marked on the board for convenience.
The DIP switch in the last image shows the correct settings for a Jamma cab (onboard sound amplification and positive video signal).
I did this conversion today and it's tested and working fine.
Kaizen0882018-07-23 11:10:51
The DK PCB was normally paired up with a Sanyo EZ20 monitor which uses negative video and has an onboard sound amp.
If you want to plug a DK PCB into a Jamma cab you need a special Jamma adapter that inverts the video signal and amplifies the audio.
I'm repairing some boards for our Australian 'Kong Off' in November that need to be able to be plugged into both an original Nintendo cab as well as a standard Jamma cab.
Fortunately the PCB is designed to be able to do this and you just need to populate it with the missing components.
Below is what you need to do to mod a board.
There's two sections on the CPU board where there are a number of unpopulated component locations.
One is video and the other is sound.
Video section...
Sound section...
The yellow jumpers are where a 10 way DIP switch needs to be fitted to swap between outputs.
This is what it looks like when modded.
The video transistors should be 2SC1815's but they're not commonly available here so they have been substituted for 2N3904's, they have a different pinout so the centre and right legs (Collector-Base) need to be swapped around.
It uses an MB3712 amp which can be substituted with an MB3713 flipped around (reverse pinout).
The correct sized 10K volume pot is also not commonly available here so I made a small riser/adapter board to in a standard trimmer pot (a 24mm pot could be remotely mounted somewhere off the board if desired), VR3/VR3/VR5 adjust the video bias.
All the component values are marked on the board for convenience.
The DIP switch in the last image shows the correct settings for a Jamma cab (onboard sound amplification and positive video signal).
I did this conversion today and it's tested and working fine.
Kaizen0882018-07-23 11:10:51
