SNESNESCUBE64 | 540 Posted June 9, 2023 Share Posted June 9, 2023 (edited) So a few months ago, I bought a Nintendo arcade board on Yahoo Auctions Japan called Head On N. It is a Nintendo counterpart of Head On by Sega. Unfortunately I don't know the story behind this one, but I figure it was just licensed to Nintendo by Sega. The main difference between the two games is that the Nintendo version is meant for a vertically oriented screen where as the Sega one is for a horizontally oriented one. Anyway, I got this thing as a converted mess. Someone had converted it to play (according to the listing) Heiankyo Alien, even modding the sound section with a weird hand built daughter card. Unfortunately I could not confirm this though, since all of the ROMs were missing on the back. So basically I had to remove everything and fix all the cut traces (there were plenty on the front and back). This was also used as a parts board at some point as well, as it was missing a lot. I did document the hacks, but I have to do a proper writeup on that. After populating everything in the sound section, I ran into the issue of ROMs. They use 2708 tri-voltage eproms, which are hard to program with modern hardware. My solution was actually to design a PCB to condense all 8 ROMs into one 2764 ROM, mapped with a 74LS148 encoder IC. It just fits into the original sockets. From there, it was time to fix the boardset, I was having graphics issues, but fortunately that was a fairly quick fix. You can read more about it on my repair log: The TLDR is that the chip that serializes graphics was faulty. After getting that replaced, I was able to actually see the game. Head On N, like with other Nintendo arcade boards, does indeed output inverted video. For this I just used a Sanyo 20EZ. It seems to be working just fine. The next step for me now is to do two things: Make a proper reset circuit and test the audio. Unfortunately I don't have a power supply in my test setup that does the -12V that it requires. I also have to hook up controls so I can actually play it. One down the road thing that I would like to do is modify the ROMs so it can just be used on an upright cabinet. It seems that it is meant to be used in a cocktail table, as it will flip the screen. It's been a fun project so far, I hope to do a custom cabinet for it one day, but that is down the road. I have to just get this board fully working first. Edited September 11, 2023 by SNESNESCUBE64 Changing the scope of the thread 2 1 Link to comment Share on other sites More sharing options...
dogbowl | 150 Posted July 8, 2023 Share Posted July 8, 2023 (edited) This is excellent work. I've never heard of this game before and while I've tackled some basic arcade PCB repair -- never would I consider something on this scale. Keep us updated Edited July 9, 2023 by dogbowl 1 1 Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted July 10, 2023 Author Share Posted July 10, 2023 (edited) I actually did get it up and running to test with sounds. I ended up redoing my test harness so that way the power lines hooked up to a separate Happ power supply. Surprisingly I only had to make one correction, I forgot to fix one cut trace. It was involved with the pellet catching sound, which sounded really flat before I fixed the trace. After that, the pellet catching sound was as correct as I could guess. The only one that I might look into is the crashing sound. it almost sounds like it is too high pitch, but it is close enough to where I don't mind. Other than the cut trace, the only other thing I did to the board itself was replace the two onboard potentiometers. I was getting a lot of inconsistencies with adjustment so I just went ahead and replaced them. One thing that I did learn, is that on the power connector, there is a reset pin. What's weird is that as long as the coin switch is hooked up, it will reset on it's own as long as that reset pin is tied high on the connector via a pullup resistor. I already had a little PCB designed though that I use for external resets on my test harnesses though. To explain the circuit, it uses a BD47xx series power supervisory IC. How it works is it monitors the 5V rail, once it crosses the set threshold, I used a BD4746 so 4.6V, it pulls the reset line low (pulled up via pullup resistor). Some games, like space invaders use an inverted version of this, hence the second active high RESET signal. Head On N uses the first active low /RESET signal on this board. By adding this reset circuit to my harness, it will be a more properly set up harness. For now, I just have an old junk microswitch hooked up as it is required for the game to operate correctly as it uses all three pins on the microswitch. At this point, the PCB deconversion is complete. It was a cool project that I hope to put into a cabinet one day. Edited July 10, 2023 by SNESNESCUBE64 Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted July 11, 2023 Author Share Posted July 11, 2023 Here are my notes from the deconversion, I had a rough time finding pinouts and stuff online, so I figure I can post it here. Unfortunately I don't remember the buttons for actual gameplay, I just kind of poked around with a ground wire to test it. I apologize, but it is a bit disorganized as this was just transcribed from my handwritten notes. PinoutsCPU Board - P1 Power GND Key GND +12V +12V +5V +5V Unused 12V Coin Counter / Lockout coil Voltage Counter/Lockout return Voltage Active Low Reset CPU Board - P2 Sound Sound out GND (Sound Return) Unused Unused CPU Board - P3 Sub Controls - - - - - GND GND GND GND GND CPU Board - P4 Main Controls - - - - - 1P Start 2P Start GND GND GND GND GND GND GND GND CPU Board - P5 Coin Blocker Coil Voltage Unused Coil Return CPU Board - P6 Coin Counter Coil Voltage Coil Return CPU Board - P7 Coin Switch Coin Switch Common Coin Switch Normally Closed Coin Switch Normally Open Video Board - P1 Video Out (Inverted Video) Green Red Blue GND GND Negative Composite Sync Video Board - P2 Power In GND Key GND GND +12V +12V +5V +5V -5V Mod Notes These were the mods that were done to the board. Stacked Chip at E4 - 74175 Connected to lower chip Unconnected/Cut Unconnected/Cut Unconnected/Cut Connected to Lower chip Floating Connected to daughtercard GND F4 Pin 9 R74, E4 Pin 7 Side Unconnected/Cut F5 Pin 17 F5 Pin 8 Unconnected/Cut Connected to daughtercard +5V 5A - LM1458 removed 5C pin 2 - Remove pin from original circuit, removed pin to +5V R42, R43, R50, R40, R41, R48, R49, R65, R21, R26, R15, R55, R66, R83, R77, R7, R8, R9 - 100k resistor removed (perhaps parts board removal) C32, C31, C18, C24, C25, C78 removed D1 - Removed (probably because parts board, replaced with 1N4007) C78 to R61 Cut C44 2.2uF -> 3A - LM741 Op Amp removed (probably because parts board) 4A - LM1458 Op Amp removed (probably because parts board) 1C pin 10 -> diode - 3B - Pin 4 1C pin 8 cut from circuit 3B-2 Pin 4, cut from circuit Trace from R67 to C43 cut Trace from R67 to 2C cut R67 -> 2C pin 15 added C40 capacitor replaced with 2.2uF 35V tantalum connected to 100k R56, R79, R89, R34 10k resistor removed R80 -> slid over to 1C pin 8 R33 -> 5E pin 15 cut, jumped to pin 14 P6 pin 10 -> Cut, jumped to RM1 pin 7 C23 10uF/25V tantalum -> .47uF electrolytic P2 pin 1 cut, 10uF tantalum added inbetween C26 -> Chagned to .0022uF mylar P4 pin 13 cut, jumped to RM2 pin 6 P4 pin 15 cut, jumped to RM2 pin 8 P3 pin 5 cut, jumped to 1G pin 5 P4 pin 5 cut, jumped to RM2 pin 7 P4 pin 6 cut, jumped to 2F pin 15 P4 pin 7 cut, jumped to 1G pin 3 C48 .047uF mylar -> 10uF 35V tantalum Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted July 11, 2023 Author Share Posted July 11, 2023 (edited) The schematic for the external soundboard, I had to make some guesses because it was damaged it seems, but this is my best guess. I attached it as a screenshot and as a PDF because VGS compresses this.Head On N Mod Board.pdf Edited July 11, 2023 by SNESNESCUBE64 Link to comment Share on other sites More sharing options...
CMR | 520 Posted July 11, 2023 Share Posted July 11, 2023 Man that is some impressive work. I'm glad you documented the mods before ripping them off. 1 Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted August 29, 2023 Author Share Posted August 29, 2023 So I decided to change the scope of this thread. I am doing a full Head On N upright cabinet. Since fixing up the PCB, I aquired a Nintendo cabinet that had been converted (and LCD'd) to a 10-yard fight themed multicade (as well as a punchout project). It was originally a Donkey Kong cabinet, so it's time to turn it into Head On N with good ole fashioned original hardware (for the most part). The first step towards the cabinet was figuring out the power supply situation. The problem is that Head On N uses a power supply with -12V and -5V. Many power supplies used in arcade cabinets had one of those but not the other. To complicate things more, the original also provided a reset signal. I took a different approach to this one. I decided to make a proper adapter board that just fits in a modern switching power supply. For this I used a Meanwell RT-125B mounted to a Donkey Kong power supply block (which was missing it's original supply). The 125B is very reliable and high quality so it was a no-brainer for me to use. It provides a -12V line which I tap from and make -5V using a 7905 regulator. The reset signal is made using a BD47xx series power monitor IC. It should work just fine, but I haven't assembled it yet. I do know that my design fits the power supply though. 1 Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted September 10, 2023 Author Share Posted September 10, 2023 I brought the cabinet home yesterday. So tonight I started the de-greening process. For this task I am using Citrusstrip, it is harsh enough to the green paint but isn't effecting the really sturdy blue gelcoat that Nintendo used back in the day. After 20-30ish minutes, the green was peeling right off. Residue was coming off easily with simple green cleaner after. It cleaned up really nicely. So far, this is just one side. I have a lot to do tomorrow, but I am hoping to be able to strip the other side and the front tomorrow. The front is going to be a bit tricky, but that is tomorrow me's problem. Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted September 11, 2023 Author Share Posted September 11, 2023 The cabinet is now for the most part de-greened. It cleaned up a lot better than I thought it would and the cabinet is really nice. The parts I need to build the harness are now on order, so I will be able to hopefully build it that this week. I also have a monitor on the bench that needs a lot of work, that will be a separate post. I was able to mount the game board, so that turned out nice. I wanted to work on and mount the coin door, but the screws that were mounting it when I got it were not correct (phillips head screws vs metric carriage bolts). The worst part is that I know I have these carriage bolts, but they are in the coin bucket of DK Jr which I took to storage. So I will have to grab them later. I was able, however, to mount new coin mechs since the ones that were on there were just spray painted face plates. These are not Asahi mechs like the original, but they are clones of the old Coin Co Asahi-clone mechs (yes, clone of a clone) that were found on old gremlin cabinets (like head on). I have a goal to have every one of my large Nintendo coin doors to be in a different configuration with the return setup, return catch, and how many mechs per machine; so this helps. Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted September 18, 2023 Author Share Posted September 18, 2023 Well I finally had time to assemble my power board and build the power wiring harness. It worked out pretty well, so I finally had this game booting for the first time in the cabinet. The only thing I had to do was add a cord cap for the light fixture because someone cut the end off. So here's what's left: Upright cabinet romset Controls wiring harness Art package needs to be made Finish ground wiring (almost done) Monitor adjustments One thing that I am a bit agitated about with my power setup, was that I decided to use the RT-125B, which was great because it has a 5V, 12V, and -12V. I used the -12V rail to make a -5V rail using a 7905 regulator. However, meanwell makes ANOTHER power supply that also includes the -5V rail built in: RQ-125B. So I might switch to that and make a new power board. Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted September 19, 2023 Author Share Posted September 19, 2023 Coins are dumb, or at least the way they are handled on this board. So the way it has to work, is there are three wires that hook up to a coin switch: Normally Open (N.O.), Normally Closed (N.C.), and Common. Head On N uses all three, where as most other games later on used just N.O. and Common. So I have a coin door harness for a Donkey Kong machine, so ideally I would like to use that, so I have to adapt it. Well this morning, I had a thought: what if I use a mosfet to drive N.C.? The whole idea is that the coin signals are pulled high via weak pullup resistors. When the switch is flicked N.C. becomes high and N.O. goes low. That said, if I add the mosfet, the weak pullup will be enabling the driving of the mosfet. When the coin switch gets flicked the mosfet is no longer engaged so the signal goes back high. So to test I just soldered the transistor to the back of the board. It worked as it should so I will make a cleaner implementation as I had to bend the transistor legs as the pinout wasn't ideal. I'll probably make a little board so I can use an SMD component, making the mod better hidden. Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted September 20, 2023 Author Share Posted September 20, 2023 Rigged up a control panel harness and modded the roms to be single player only. Reason I chose single player only is because I am trying to figure out how to make two player mode work without flipping the screen. Head On N is meant to be in a cocktail table, unfortunately there is no dip switch for setting it to upright from what I can figure out. Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted September 26, 2023 Author Share Posted September 26, 2023 (edited) I am still working on Head On N, I have most of the modifcations I need to make to the ROMs to make it work properly in an upright cabinet done. Just a couple things left. From there it's just art. https://youtu.be/3UxzfF92F0I?si=a9lsUj5Z0hCYg6Uy Edited September 26, 2023 by SNESNESCUBE64 Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted October 3, 2023 Author Share Posted October 3, 2023 (edited) Well I am done messing around with the ROMs. I finished making the upright version of the ROMs. On top of that I even made a freeplay mod because most of the rest of my games are freeplay. What's next: - Custom artwork - Update power board to support RQ-125B power supply and switch to that supply - Update ROM board to have switches to enable/disable freeplay and switch to cocktail table mode. Edited October 3, 2023 by SNESNESCUBE64 Link to comment Share on other sites More sharing options...
CMR | 520 Posted October 5, 2023 Share Posted October 5, 2023 Nice work. I'm looking forward to seeing the completed cabinet when you get it done. 1 Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted October 9, 2023 Author Share Posted October 9, 2023 I finalized the hardware stuff this weekend. I designed a new ROM board to be able to switch between upright and cocktail versions as well as freeplay versions. I also modified my power supply adapter for use on a different supply more suited for this application. I also rerouted the power switch to be inside the coin door area like I did with my other Nintendo cabinets. Nintendo put the switch on the back and it is really inconvenient. The last thing I did was make a back door sheet. I cannot do the artwork, but I made this one in the style of Radarscope/early donkey kong back door sheets. Attached it both as an image and pdf due to compression. Head On N Backdoor Sheet.pdf 1 Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted November 3, 2023 Author Share Posted November 3, 2023 Updated my coin mod to be a cleaner mod. I made a tiny pcb (as small as oshpark will let me make). Also made an updated version of the power supply breakout to utilize the RQ-125B instead of RT-125B. It eliminates the need to include an inefficient 7905 on the breakout. Making it this was also reduces the size of the board. 1 Link to comment Share on other sites More sharing options...
SNESNESCUBE64 | 540 Posted November 8, 2023 Author Share Posted November 8, 2023 Finally got around to printing my back door sheet. If I had to change one thing, I'd make the text less bold. But it turned out great. Compared to a DK Jr sheet Link to comment Share on other sites More sharing options...
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