TG16:FRAM/FeRAM Mod

With the introduction of the PC Engine CD in 1988, NEC also introduced a way for people to save their games due to the read-only nature of CD-ROM media and the lack of any save methods for HuCards at the time. This was accomplished by using a 2 KB SRAM (static RAM) chip backed by a 0.47F supercapacitor, which is charged by the system's 5V rail and provides power to the SRAM chip even when the system is powered off. This method has a significant flaw in that if the system is not powered on within two to three weeks, the supercapacitor will lose charge and all saves will be lost. Thankfully this can be rectified by replacing the original SRAM chip with a modern FRAM chip, which can retain data for decades without needing a power source.

Materials required

• 4.5 mm gamebit screwdriver (for most systems)
• T10 security screwdriver (for Japanese Duo consoles and Super CD-ROM2)
• Phillips head screwdriver
• FM16W08 FRAM chip (best to source this from Digi-Key or Mouser when available as sites like eBay and Aliexpress contain counterfeits)
• Temperature-controlled soldering iron (preferably with a J-hook tip)
• Hot air station
• Kapton tape and/or aluminum foil
• Leaded solder
• Flux
• Desoldering braid
• Desoldering gun (optional)
• Multimeter
• Magnet wire (for systems where an adapter PCB is not available)
  

Installation

The principles behind the FRAM mod remain the same for all PC Engine/TurboGrafx-16 systems which have memory backup, but the method varies significantly between them.

PC Engine Duo/TurboDuo

1. Flip the console over and unscrew the five security screws (4.5 mm gamebit screws on the TurboDuo, T10 security screws on the PCE Duo), then remove the top case.
2. Remove the screws holding the motherboard down to the bottom case and disconnect the CD drive and power jack. Unsolder the two ground wires from the CD drive, there is one connected to the bottom RF shielding and another on the right-hand edge of the motherboard. If you have a TurboDuo, you will also need to remove the top RF shield which covers most of the internals.
3. With the motherboard removed, locate the save RAM chip. It is a Sanyo LC3517BML-15 chip located immediately to the right of the right-hand heat sink.
4. Place Kapton tape or tin foil around the components in the vicinity of the SRAM chip so that they will not be damaged or accidentally removed during the removal process.
5. Set your hot air station for low to medium airflow and set the temperature for around 335 degrees Celsius. Hold the nozzle within an inch of the chip and swirl it around so that the heat is applied evenly. After about 10-15 seconds, the SRAM chip should become loose. Carefully remove it from the board and set it aside. Do not force it or make any fast movements as you could damage or lift pads.
6. Though this is optional, you may also want to take the opportunity to remove the supercapacitor since it will now be redundant.
7. Clean the pads by applying flux and then carefully and lightly dragging desoldering braid over them. Once the old solder has been removed, clean off the area with IPA or flux remover.
8. To simplify the installation of the FRAM chip, PC Engine developer David Shadoff has designed a flex PCB which sits over the pads for the SRAM chip and reroutes these pads to the appropriate pins on the FRAM chip.
9. Align the flex so that the open part of the "U" is oriented towards the top of the chip and the castellations line up with the pads. Solder one castellation down to anchor it to the board and check your alignment again.
10. If the alignment is good, apply a generous amount of flux to the board and then put a small amount of solder on the tip of your iron. Drag the tip across the pads so that the solder flows evenly; the flux will do most of the work for you. If you wind up with a solder bridge, apply more flux and "sweep" the excess solder away onto your iron tip.
11. Check that all your connections are good and that the castellations are properly connected. You will not be able to access these points once the FRAM chip is installed so double or triple check if you need to.
12. With the flex secured, solder two 0603 47k ohm resistors on the pads below the copyright text. You will need these resistors present regardless if you want to use the extra banks on the FRAM chip or not.
13. Now that the flex is ready, you can begin installing the FRAM chip itself. Align it so that the top of the chip corresponds to the open part of the "U" and the top of the original SRAM chip. Anchor down one of the corner pins and verify your alignment before installing. Solder the FRAM chip as you did with the flex PCB; apply a large amount of flux, put a small blob of solder on your iron tip, then drag the tip across the pins to solder them to the flex.
14. After the FRAM chip has been soldered down, check your work visually and use a multimeter to verify the connections.
15. Reassemble the Duo and turn it on without a HuCard inserted. When the Super CD-ROM2 System splash screen appears, press Select to enter the backup memory menu. Select the middle option to format the backup memory. If the FRAM install was performed correctly you should not encounter any errors.
16. Test with a game which saves to backup memory, then boot the system without a HuCard. Press Select on the splash screen and select the top option to delete a save file. If there is a save file present, congratulations! No longer will you need to keep your system constantly powered on to retain your precious save files, and they will always be there no matter if it's been a day or 30 days since you last powered it on!

Duo-R/Duo-RX

1. Flip the console over and unscrew the five T10 security screws. Carefully pull off the top case as the CD door pinswitch is connected to the motherboard on the right-hand side. Remove the connector for the pinswitch and you can now set the top case aside.
2. Remove the screws holding the motherboard down to the bottom case and disconnect the CD drive. Set the CD drive aside and you can now remove the motherboard.
3. With the motherboard removed, locate the save RAM chip. It is located on the underside of the motherboard towards the front left-hand edge and labeled IC512.
4. Place Kapton tape or tin foil around the components in the vicinity of the SRAM chip so that they will not be damaged or accidentally removed during the removal process.
5. Set your hot air station for low to medium airflow and set the temperature for around 335 degrees Celsius. Hold the nozzle within an inch of the chip and swirl it around so that the heat is applied evenly. This may take a while as the SRAM chip is secured by small blobs of epoxy to the motherboard, not unlike certain Sega Saturn board revisions. After about 15-20 seconds, the SRAM chip should become loose. Carefully remove it from the board and set it aside. Do not force it or make any fast movements as you could damage or lift pads or traces.
6. Though this is optional, you may also want to take the opportunity to remove the supercapacitor since it will now be redundant.
7. Clean the pads by applying flux and then carefully and lightly dragging desoldering braid over them. Once the old solder has been removed, clean off the area with IPA or flux remover.
8. Although designed for the original Duo, David Shadoff's flex PCB also works with the Duo-R.
9. Align the flex so that the open part of the "U" is oriented towards the top of the chip and the castellations line up with the pads. Solder one castellation down to anchor it to the board and check your alignment again.
10. If the alignment is good, apply a generous amount of flux to the board and then put a small amount of solder on the tip of your iron. Drag the tip across the pads so that the solder flows evenly; the flux will do most of the work for you. If you wind up with a solder bridge, apply more flux and "sweep" the excess solder away onto your iron tip.
11. Check that all your connections are good and that the castellations are properly connected. You will not be able to access these points once the FRAM chip is installed so double or triple check if you need to.
12. With the flex secured, solder two 0603 47k ohm resistors on the pads below the copyright text. You will need these resistors present regardless if you want to use the extra banks on the FRAM chip or not.
13. Now that the flex is ready, you can begin installing the FRAM chip itself. Align it so that the top of the chip corresponds to the open part of the "U" and the top of the original SRAM chip. Anchor down one of the corner pins and verify your alignment before installing. Solder the FRAM chip as you did with the flex PCB; apply a large amount of flux, put a small blob of solder on your iron tip, then drag the tip across the pins to solder them to the flex.
14. After the FRAM chip has been soldered down, check your work visually and use a multimeter to verify the connections.
15. Reassemble the Duo4g and turn it on without a HuCard inserted. When the Super CD-ROM2 System splash screen appears, press Select to enter the backup memory menu. Select the middle option to format the backup memory. If the FRAM install was performed correctly you should not encounter any errors.
16. Test with a game which saves to backup memory, then boot the system without a HuCard. Press Select on the splash screen and select the top option to delete a save file. If there is a save file present, congratulations! No longer will you need to keep your system constantly powered on to retain your precious save files, and they will always be there no matter if it's been a day or 30 days since you last powered it on!

IFU-30A

1. Flip the interface over and unscrew only the three long 4.5 mm gamebit screws toward the back. You do not need to take out all the screws as the internals are all inside the rear gray section. Carefully undo the three tabs holding the gray section together and manipulate the eject lever so that it can be worked free. Make sure to remove the connector for the power LED before completely separating the two halves.
2. Remove the two screws near the CD drive connector and disconnect the power switch and AV/power jack block on the left-hand side. Lift up the board and then unscrew the ground lug connecting the SRAM board shielding to the bottom RF shield.
3. With the motherboard removed, carefully and slowly remove the SRAM board that sits near the PC Engine connector. This PCB is attached by several dense connectors around its perimeter so make sure to go around and loosen each one before taking the board off.
4. With the SRAM board removed, locate the save RAM chip. It should be located right next to the green supercapacitor that powers it.
5. Place Kapton tape or tin foil around the components in the vicinity of the SRAM chip so that they will not be damaged or accidentally removed during the removal process.
6. Set your hot air station for low to medium airflow and set the temperature for around 335 degrees Celsius. Hold the nozzle within an inch of the chip and swirl it around so that the heat is applied evenly. After about 10-15 seconds, the SRAM chip should become loose. Carefully remove it from the board and set it aside. Do not force it or make any fast movements as you could damage or lift pads.
7. Though this is optional, you may also want to take the opportunity to remove the supercapacitor since it will now be redundant.
8. Clean the pads by applying flux and then carefully and lightly dragging desoldering braid over them. Once the old solder has been removed, clean off the area with IPA or flux remover.
9. Take your FRAM chip and prepare it for installation. You will need to lift up five pins on it before it can be soldered to the board. This is because the FM16W08's pinout doesn't quite line up with the original SRAM chip. This includes the 5V and write enable pins which are crucial to the chip functioning properly. Lift pins 1 (not connected), 2 (A12), 23 (A11), 27 (write enable) and 28 (5V). You can also snip off pin 1 as it is not connected and is therefore useless.
10. Carefully align the FRAM chip so that the back pins correspond with those of the original SRAM chip.
11. Apply a generous amount of flux to the area and solder one of the back pins to anchor down the chip. Check your alignment to ensure that are no pins overlapping pads and that the pins sit in the center of the pads.
12. Once you have verified that the chip is aligned, you may proceed with soldering it to the board. Place a small blob of solder on the tip of your iron and slowly drag the tip across the pins, watching out for the ones you have lifted. The flux will do most of the work for you and will help to spread the solder evenly across the pins. If you have solder bridging a couple of pins, apply more flux and "sweep" the excess solder away so that it collects on your tip.
13. With the FRAM chip soldered down, inspect your work. You may also use a multimeter in continuity mode to ensure that the pins are properly connected.
14. Using magnet wire, connect pin 28 of the FRAM chip to pin 26. Pin 26 is unused on the FRAM chip and is soldered to the 5V line of the original SRAM chip.
15. Connect pin 27 of the FRAM chip to the pad sitting underneath pin 23. This is the write enable line which was previously connected to pin 21 of the original SRAM chip.
16. Connect both pins 2 and 23 of the FRAM chip to either 5V or ground, as these are unused address lines.
17. When rewiring is complete, inspect your work again and use your multimeter to check for possible shorts and that everything is properly connected.
18. Reassemble the IFU and plug in a PC Engine with a system card inserted (any will do). When the CD-ROM2 System splash screen appears, press Select to enter the backup memory menu. Select the middle option to format the backup memory. If the FRAM install was performed correctly you should not encounter any errors.
19. Test with a game which saves to backup memory, then use the CD system card to verify that the game was able to save a file. Press Select on the splash screen and select the top option to delete a save file. If there is a save file present, congratulations! No longer will you need to keep your system constantly powered on to retain your precious save files, and they will always be there no matter if it's been a day or 30 days since you last powered it on!

TurboGrafx-CD

1. Flip the dock over and unscrew only the three long 4.5 mm gamebit screws toward the back. You do not need to take out all the screws as the internals are all inside the rear section where the CD drive sits. Carefully pull the rear section off and disconnect the power switch connector.
2. You will see that the main board and sub board with the expansion connector are sandwiched together inside the rear section. Unscrew the four Phillips head screws on the main board and then unsolder the two grounding straps which connect the sub board's shielding to the shielding lining the inside of the case. This should free the "sandwich" from the case.
3. Flip the "sandwich" over and unscrew the four screws that secure the sub board to the plastic spacer underneath it.
4. To fully free the assembly, you must undo the three black screws securing the CD drive connector board and the small screw that holds in the pinswitch for the CD drive lock.
5. With all the boards liberated from the case, remove the RF shielding over the sub board and desolder the two grounding straps on top of the expansion connector. Once the outer shielding is removed, desolder the inner shield on the bottom of the sub board to expose all the solder joints.
6. Locate the save RAM chip. It should be located right next to the green supercapacitor that powers it.
7. Place Kapton tape or tin foil around the components in the vicinity of the SRAM chip so that they will not be damaged or accidentally removed during the removal process.
8. Set your hot air station for low to medium airflow and set the temperature for around 335 degrees Celsius. Hold the nozzle within an inch of the chip and swirl it around so that the heat is applied evenly. After about 10-15 seconds, the SRAM chip should become loose. Carefully remove it from the board and set it aside. Do not force it or make any fast movements as you could damage or lift pads.
9. Though this is optional, you may also want to take the opportunity to remove the supercapacitor since it will now be redundant.
10. Clean the pads by applying flux and then carefully and lightly dragging desoldering braid over them. Once the old solder has been removed, clean off the area with IPA or flux remover.
11. Take your FRAM chip and prepare it for installation. You will need to lift up five pins on it before it can be soldered to the board. This is because the FM16W08's pinout doesn't quite line up with the original SRAM chip. This includes the 5V and write enable pins which are crucial to the chip functioning properly. Lift pins 1 (not connected), 2 (A12), 23 (A11), 27 (write enable) and 28 (5V). You can also snip off pin 1 as it is not connected and is therefore useless.
12. Carefully align the FRAM chip so that the back pins correspond with those of the original SRAM chip.
13. Apply a generous amount of flux to the area and solder one of the back pins to anchor down the chip. Check your alignment to ensure that are no pins overlapping pads and that the pins sit in the center of the pads.
14. Once you have verified that the chip is aligned, you may proceed with soldering it to the board. Place a small blob of solder on the tip of your iron and slowly drag the tip across the pins, watching out for the ones you have lifted. The flux will do most of the work for you and will help to spread the solder evenly across the pins. If you have solder bridging a couple of pins, apply more flux and "sweep" the excess solder away so that it collects on your tip.
15. With the FRAM chip soldered down, inspect your work. You may also use a multimeter in continuity mode to ensure that the pins are properly connected.
16. Using magnet wire, connect pin 28 of the FRAM chip to pin 26. Pin 26 is unused on the FRAM chip and is soldered to the 5V line of the original SRAM chip.
17. Connect pin 27 of the FRAM chip to the pad sitting underneath pin 23. This is the write enable line which was previously connected to pin 21 of the original SRAM chip.
18. Connect both pins 2 and 23 of the FRAM chip to either 5V or ground, as these are unused address lines.
19. When rewiring is complete, inspect your work again and use your multimeter to check for possible shorts and that everything is properly connected.
20. Reassemble the dock, paying very close attention to the order of assembly. The TurboGrafx-CD dock is a rather convoluted piece of hardware so take your time.
21. After reassembly, plug in a TurboGrafx-16 with a system card inserted (any will do). When the TurboGrafx-CD splash screen appears, press Select to enter the backup memory menu. Select "Format" to format the backup memory. If the FRAM install was performed correctly you should not encounter any errors.
22. Test with a game which saves to backup memory, then use the CD system card to verify that the game was able to save a file. Press Select on the splash screen and select "Delete" to delete a save file. If there is a save file present, congratulations! No longer will you need to keep your system constantly powered on to retain your precious save files, and they will always be there no matter if it's been a day or 30 days since you last powered it on!

Tennokoe 2

The Tennokoe 2 (天の声2, meaning Voice From the Heavens) was an add-on released in late 1989 by Hudson Soft, the designers of the PC Engine hardware. It functions in much the same way as the CD systems' memory backup, but instead of using a supercapacitor to hold charge, it uses two user-replaceable AA batteries in order to reduce cost. Unlike most CD hardware, it uses a through-hole DIP SRAM chip, again done to save cost. Despite all this, the Tennokoe 2 can also be modified with FRAM though in a different manner. Because modern FRAM chips are SMD components, the use of a special adapter board is required. Developer David Shadoff has also designed a PCB which serves this purpose.

1. Flip over the Tennokoe 2 and remove any batteries that are present, then remove the screws holding it together. Remove the board from the case and set it aside.
2. The SRAM is the only chip on the top side of the board and hence is very easy to locate. Carefully desolder it from the board using a desoldering gun or desoldering braid with flux, then set it aside.
3. Next you will need to prepare the adapter PCB. Insert two 12-pin headers into the board where it will sit in place of the SRAM chip, but do so in a way that the pins do not protrude from the board.
4. Solder two 0805 47k ohm resistors on the pads labeled R1 and R2. You will need these resistors regardless if you plan to use the extra banks of the FRAM chip or not.
5. Carefully align the FRAM chip so that the top of the chip faces towards the resistors and bank selection area on the adapter PCB.
6. Apply a generous amount of flux to the area and solder one of the back pins to anchor down the chip. Check your alignment to ensure that are no pins overlapping pads and that the pins sit in the center of the pads.
7. Once you have verified that the chip is aligned, you may proceed with soldering it to the board. Place a small blob of solder on the tip of your iron and slowly drag the tip across the pins, watching out for the ones you have lifted. The flux will do most of the work for you and will help to spread the solder evenly across the pins. If you have solder bridging a couple of pins, apply more flux and "sweep" the excess solder away so that it collects on your tip.
8. With the FRAM chip soldered down, inspect your work. You may also use a multimeter in continuity mode to ensure that the pins are properly connected.
9. Place the prepared adapter board into the holes where the original SRAM chip was so that the top of the FRAM chip faces towards the expansion connector. Flip over the Tennokoe 2 board and solder the adapter PCB into place.
10. Reassemble the Tennokoe 2, minding the position of the LED so that it is aligned properly inside the case.
11. Plug in a PC Engine and test with a game which saves to backup memory, then use a CD-ROM2 system card (any will do) to verify that the game was able to save a file. Press Select on the splash screen and select "Delete" to delete a save file. If there is a save file present, congratulations! Your Tennokoe 2 no longer needs to be fed a supply of batteries to keep your saves preserved!