Problem: Swapping arcade boards requires fiddling with the remote board to dial in 9 settings (Contrast, R gain, B gain G gain, Brightness, H Size, H Posi, V Size, V Posi). This can sometimes involve lifting the bonnet to get the screen size and position set just right. Its not that hard to do, just somewhat annoying when you want to plug in a game and go.
Solution: A 'Smart' remote board that can save your settings and can load them as needed. A smart remote board would have POTs just like a normal remote board. It would additionally have a ADC, 9 channel DAC, adrunio, small screen and navigation buttons. You would have to manually adjust the monitor the first time using the pots, you could then hit a button to have the ADC sample the voltages set on the 9 POTs. Those voltages are saved in the ardunio. The ardunio then commands the 9 channels of the DAC to drive the voltages the ADC just read in.
https://wiki.arcadeotaku.com/images/8/81/Nanao_MS9_Schematic_1.jpg
https://wiki.arcadeotaku.com/images/a/a3/Nanao_MS9_Schematic_2.jpg
It appears that 12 volts comes into the remote board, there are 2 fixed resistors and a pot that form a voltage divider. The 2 fixed resistors will set the min and max band and the pot will adjust inside that band. Thinking something along the lines of 6 volts when pot in centered with min and max values of 3-9 volts, I will have to get the actual resistor values to figure out the ratios exactly, this is just some rough estimation.
Could also use some form of digital potentiometer if the risk of changing the underlying circuit poses some risk of damaging the monitor. I find it hard to believe that the remote board provides little more than reference voltages being it just hangs off the monitor chassis with a long, un-shielded cable. I see 2 main requirements for the output reference voltages:
-Protection diodes to clamp the output voltage of the DAC to the same range allowed by the POT and fixed resistors of the stock remote board,
-Slew rate is controlled nice and slow like would be done with a human and a POT, potentially add some capacitance on the output to get an RC constant to slow things down a bit. This thing doesn't need to go very fast.
Challanges:
Can the 12 volts that is supplied to the remote board, once stepped down to 5 volts, provide enough current to power an arduino, OLED screen, DAC?
What is the availability of 9+ channel DAC that support 12 volt rails?
How do you cleanly switch from manual to remote without the monitor going crazy during the transitions? I was thinking of putting some ceramic caps in parallel with the POTs to give me an RC constant. Hopefully I can get a large enough RC constant that it doesn't slow down the responsiveness of the POT adjustments, but large enough that I can withstand the switch from the voltage dividers to the DACs, without the monitor seeing those voltages drop and resizing the screen momentarily.
These voltages set by the POTs are fed into somewhat complex analog circuits (Not the RGB gains, those go into an IC) - Am I over simplifying the circuit down to a voltage divider and neglecting things like current. Not sure exactly what will happen when I drive a voltage using a DAC rather than a voltage created from a divider with a POT. I am assuming as long as I used the same power rails to create the voltage, the DAC should function somewhat the same.
So that is about as far as I have brainstormed this out. Seeing Frank make those cool OLED multi selectors really kicked this project to the front of mind as I would love to have that interface to select monitor profiles. Lets poke at this idea and if it hold water I will start the component hunt and PCB layout.
Documenting MS9 Remote Board:
https://imgur.com/a/MHODFTe
Service Manual for Sega Touring Car - has wonderful BOM, schematic, etc for MS9
https://www.gamesdatabase.org/Media...ga_Touring_Car_Championship_-_1996_-_Sega.pdf
So I noticed that the schematic on AO and the schematic in the Sega Touring Car Service Manual (PDF page 185) have slight differences with respect to the remote board schematic, specifically in the Sega Touring Car Service Manual, there are 3 Diodes in series on the H.Size control.
The Diodes (D213, D214, D215) are not shown in the AO schematic for the MS9, however both schematics have the same title Block "MS9-29SU Schematic Diagram" and same Drawing No. (E-B0279 (5T01087))
The schematic on AO, has the date of May 1994, whereas the date on the Sega Touring Car Service Manual is June 1994.
So what is the deal with the 3 extra diodes in series? These diodes (D213, D214, D215) have 2 didoes in the package and the schematic seems to imply both are in series, so a total of 6 Diodes in series. If you assume a drop of 0.7v per PN junction, thats something like 4.2 volt drop across all those diodes. Depending on how the H size set point voltage is used internally, I can see this making the H size either more narrow or more wide.
Design:
Github Link
https://github.com/wifiber/Smart-Remote-Board-MS9
I am using the original Potentiometer values and fixed resistor values - this hopefully will ensure that each POT has the same feel to it. These POTs are feed into (2) different 4:1 MUX. These are nice Analog Devices (AD) MUX with very low turn on resistance. The output from the MUX is fed into a pair of buffer op amps. These OP AMPs present up a nice high impedance input to the POTs that are setting the reference voltages and get the voltage division I need to go into the 0-5V DAC on the Arduino. The remote board is all referenced to 12 volts. The Arduino will accept up to 12 Volt input to its 5V regulator, but all the logic levels on the Arduino need to be 5V TTL. I am using a voltage divider on the output of the OP AMP to scale down the voltage from 0-12V range to 0-4.8V range, before being fed into the 10-BIT ADC built into the Arduino. The Arduino will cycle thorough all 4 channels of the MUX, and use its internal ADC to sample the voltages set by the POTS. The voltage set by the contrast POT is sampled similar, but not through the 4:1 MUX, this was mainly done by the package constraints of buffers/amplifiers. Have 9 separate POTs on the remote board and many buffers/amps are 4/8/16 Inputs. Once the voltages are sampled by the Ardunio, they can be displayed numerically on the OLED or saved as game profiles that can be recalled later - the main focus of this project.
Recalling the sampled values is done via a DAC (Digital to Analog Converter). The Arduino output is connected to an 8 bit, parallel DAC. The sampled voltages set by the POTs will be sent out to the DAC, which in turn feeds some high precision sample and hold amplifiers (S/H). The S/H amplifiers will be presenting up these reference voltages to the MS9 main chassis, in place of the POTs. By using S/H amplifiers, that are updated by the DAC every few 100ms this board should be able to achieve very good voltage stability.
Planning on having a small screen and button for seeing and recalling game settings, as well as live display of current POT values .
Note - I didn't include the diodes on the Hsize line as I am trying to keep the part count down and I believe that just sets minimum width for the H size. Will need further testing and pry add the pads for the diodes if needed later, this is still in early Alpha stages.
Solution: A 'Smart' remote board that can save your settings and can load them as needed. A smart remote board would have POTs just like a normal remote board. It would additionally have a ADC, 9 channel DAC, adrunio, small screen and navigation buttons. You would have to manually adjust the monitor the first time using the pots, you could then hit a button to have the ADC sample the voltages set on the 9 POTs. Those voltages are saved in the ardunio. The ardunio then commands the 9 channels of the DAC to drive the voltages the ADC just read in.
https://wiki.arcadeotaku.com/images/8/81/Nanao_MS9_Schematic_1.jpg
https://wiki.arcadeotaku.com/images/a/a3/Nanao_MS9_Schematic_2.jpg
It appears that 12 volts comes into the remote board, there are 2 fixed resistors and a pot that form a voltage divider. The 2 fixed resistors will set the min and max band and the pot will adjust inside that band. Thinking something along the lines of 6 volts when pot in centered with min and max values of 3-9 volts, I will have to get the actual resistor values to figure out the ratios exactly, this is just some rough estimation.
Could also use some form of digital potentiometer if the risk of changing the underlying circuit poses some risk of damaging the monitor. I find it hard to believe that the remote board provides little more than reference voltages being it just hangs off the monitor chassis with a long, un-shielded cable. I see 2 main requirements for the output reference voltages:
-Protection diodes to clamp the output voltage of the DAC to the same range allowed by the POT and fixed resistors of the stock remote board,
-Slew rate is controlled nice and slow like would be done with a human and a POT, potentially add some capacitance on the output to get an RC constant to slow things down a bit. This thing doesn't need to go very fast.
Challanges:
Can the 12 volts that is supplied to the remote board, once stepped down to 5 volts, provide enough current to power an arduino, OLED screen, DAC?
What is the availability of 9+ channel DAC that support 12 volt rails?
How do you cleanly switch from manual to remote without the monitor going crazy during the transitions? I was thinking of putting some ceramic caps in parallel with the POTs to give me an RC constant. Hopefully I can get a large enough RC constant that it doesn't slow down the responsiveness of the POT adjustments, but large enough that I can withstand the switch from the voltage dividers to the DACs, without the monitor seeing those voltages drop and resizing the screen momentarily.
These voltages set by the POTs are fed into somewhat complex analog circuits (Not the RGB gains, those go into an IC) - Am I over simplifying the circuit down to a voltage divider and neglecting things like current. Not sure exactly what will happen when I drive a voltage using a DAC rather than a voltage created from a divider with a POT. I am assuming as long as I used the same power rails to create the voltage, the DAC should function somewhat the same.
So that is about as far as I have brainstormed this out. Seeing Frank make those cool OLED multi selectors really kicked this project to the front of mind as I would love to have that interface to select monitor profiles. Lets poke at this idea and if it hold water I will start the component hunt and PCB layout.
Documenting MS9 Remote Board:
https://imgur.com/a/MHODFTe
Service Manual for Sega Touring Car - has wonderful BOM, schematic, etc for MS9
https://www.gamesdatabase.org/Media...ga_Touring_Car_Championship_-_1996_-_Sega.pdf
So I noticed that the schematic on AO and the schematic in the Sega Touring Car Service Manual (PDF page 185) have slight differences with respect to the remote board schematic, specifically in the Sega Touring Car Service Manual, there are 3 Diodes in series on the H.Size control.
The Diodes (D213, D214, D215) are not shown in the AO schematic for the MS9, however both schematics have the same title Block "MS9-29SU Schematic Diagram" and same Drawing No. (E-B0279 (5T01087))
The schematic on AO, has the date of May 1994, whereas the date on the Sega Touring Car Service Manual is June 1994.
So what is the deal with the 3 extra diodes in series? These diodes (D213, D214, D215) have 2 didoes in the package and the schematic seems to imply both are in series, so a total of 6 Diodes in series. If you assume a drop of 0.7v per PN junction, thats something like 4.2 volt drop across all those diodes. Depending on how the H size set point voltage is used internally, I can see this making the H size either more narrow or more wide.
Design:
Github Link
https://github.com/wifiber/Smart-Remote-Board-MS9
I am using the original Potentiometer values and fixed resistor values - this hopefully will ensure that each POT has the same feel to it. These POTs are feed into (2) different 4:1 MUX. These are nice Analog Devices (AD) MUX with very low turn on resistance. The output from the MUX is fed into a pair of buffer op amps. These OP AMPs present up a nice high impedance input to the POTs that are setting the reference voltages and get the voltage division I need to go into the 0-5V DAC on the Arduino. The remote board is all referenced to 12 volts. The Arduino will accept up to 12 Volt input to its 5V regulator, but all the logic levels on the Arduino need to be 5V TTL. I am using a voltage divider on the output of the OP AMP to scale down the voltage from 0-12V range to 0-4.8V range, before being fed into the 10-BIT ADC built into the Arduino. The Arduino will cycle thorough all 4 channels of the MUX, and use its internal ADC to sample the voltages set by the POTS. The voltage set by the contrast POT is sampled similar, but not through the 4:1 MUX, this was mainly done by the package constraints of buffers/amplifiers. Have 9 separate POTs on the remote board and many buffers/amps are 4/8/16 Inputs. Once the voltages are sampled by the Ardunio, they can be displayed numerically on the OLED or saved as game profiles that can be recalled later - the main focus of this project.
Recalling the sampled values is done via a DAC (Digital to Analog Converter). The Arduino output is connected to an 8 bit, parallel DAC. The sampled voltages set by the POTs will be sent out to the DAC, which in turn feeds some high precision sample and hold amplifiers (S/H). The S/H amplifiers will be presenting up these reference voltages to the MS9 main chassis, in place of the POTs. By using S/H amplifiers, that are updated by the DAC every few 100ms this board should be able to achieve very good voltage stability.
Planning on having a small screen and button for seeing and recalling game settings, as well as live display of current POT values .
Note - I didn't include the diodes on the Hsize line as I am trying to keep the part count down and I believe that just sets minimum width for the H size. Will need further testing and pry add the pads for the diodes if needed later, this is still in early Alpha stages.
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CS for DAC)(Pin D4, DAC-AB/sample and hold) need to look for logic conflicts, but it seemed to be alright on the surface. Knowing that the Enable line for the input mux isn't needed when the CS line for the output DAC is needed. Also using the DAC AB select line and the Sample/Hold signal seems alright as long as I select the correct DAC (DAC B) and the correct mode for the S/H (Sample).
