Sharp x68000 Repair

[Arcade King]

I'll be working on this thread over the next several days so it will stay closed until completed.

As a Retro Arcade, Computer and Console enthusiast I think it's all our dreams to own somthing special like the Sharp x68000 which was the pinacle of 16 bit computers of the day even stomping on greats like the Amiga.

I recently purchased 2 orignal model (OG) Sharp x68000's (CZ-600CE) , one from Ebay the other from a Japanese Proxy site. The one from Ebay I found out was some guy pre listing the computer on Ebay. This is why you some times see the same item from Japan listed from multiple sellers on Ebay. You buy it from them, they then buy it from what ever Japanese site it was listed on, have it sent to them, then they send it to you.

As I found out with the second computer it's far cheaper to use a Japanese Proxy site and buy it directly from the seller.

A Run down on both machines.

Both machines came without keyboard and mouse which is pretty common and both listed as Junk.

Ebay machine.

This machine had obviously been worked on before. I'd say it's a very early model, there are a lot of jumpers and external parts added to all of the PCB's. The case has been damaged with tabs that clip the case together broken off , many screws missing, RF shielding missing, internal speaker was missing and lastly the floppy status indicator LED board missing 😕 other than that all boards and floppy drives present.

Proxy site machine.

Later revision, all boards very clean without the hacks found on the earlier revision, Everything present in this machine including screws, RF shielding, Floppy drives, Speaker etc.

Both machines didn't have the 1mb upgrade. 😞 I havent seen any come up for sale as of yet and you need at least 2mb to run most games.

Latest Edition.

I have an Illness yes i know.

Model CZ-613C-BK (EXPERT HD)

This model has 2 megs of ram standard and a 40 MB SASI hard drive installed.

Overall in good condition, no signs of tampering and has 2 disks left in the drive. No Keyboard or Mouse.

Power Supply

Before even attempting to power on the machines it's important to either rebuild the original PSU and run off a 100vac step down or in my case I used a more modern solution called X68k Pico PSU v2 created by mattsoft and is open source on github. https://github.com/mattsoft/X68K_Pico_PSU_v2

Its essentially a board that replaces the guts of an original x68000 psu with a ATX PicoPSU https://mini-box.com.au/product/picopsu-120-120w/

Original PSU

X68k PicoPSU

I would have prefered something that fit direcly into the existing case however I adapted it for now and works fine.

This board was designed for later model machines like the ACE, Expert, PRO etc with the "Tetris" style PSU. The PSU was changed from the OG rectangular style to the Tetris style to make room for a SCSI hard drive.

Because I need a second PSU for my other machine I decided to redesign the board using KiCad to better suit OG models.

Firstly I measured the original PSU case which has spacers already installed to screw down the PSU's internal so I've made the board larger to suit. Secondly I've done away with the screw terminals in favour of 3.96mm Molex headers and plugs which I use all the time in my Pinball repairs. I've moved the headers closer to the top right to get everything closer to the hole for the wires. The last change was adding extra terminals for the +5VSB which is Standby power which like on modern PC's is used to soft start the computer with the button on the front, it's also used for ejecting disks when the machine is in standby mode with a button on the back on the X68k.

There are 3 white wires on the OG x68k for +5vSB with only 1 terminal on the Tetris PicoPSU board which makes it hard. On mine I've made sure there is enough room for all wires.

Crossing my fingers when my boards come back they will fit in.

UPDATE.

I wasn't happy with my v1 board so I had it remade doubling the track size from 1.5 to 3.0mm and added a Molex header in for the 12v fan, something I should have done in the first place.

V1 vs V2

Everything neatly installed.

and back in the machine. You wouldnt even know it wasnt the original psu.

I can confirm everything is powering up and working beautifully 🙂

[Arcade King]

Now We have the PSU sorted its time to look at the boards.

x68000 boards are split into 3.

Info can be found of the Wiki https://en.wikipedia.org/wiki/X68000

The main CPU or "Core" board which as the main 68000 CPU clocked at 10mhz, 1mb of roms , 16k of Battery backed up SRAM (bottom right) and the CYNTHIA sprite controller chip at the top left.

Video Board which has the VSPO video processor and VRAM

and lastly Peripheral board which sits at the bottom and tends to get very dirty with dust and crap. This board has the sound, floppy and SASI controller hardware.

x68k 1 Repair.

First off was to give the dirty Peripheral board a clean and deal with the battery on the main CPU (Core) board.

It's well documented that the biggest killers of the OG x68000's is battery leakage from the old 3.6v Ni-CD battery which sits right next to the main 69mhz crystal and reset chip.

As you can see somebody had already clipped out the battery and luckily minimum damage done. This early CE has the crystal on a some standoff which is super lucky, most have them flat on the board.

I decided to use a 3.6 volt lithium battery with axial leads. Looking at the schematics it's just a matter of cutting off the charge resistor R88 and install the battery.

Eventually I'll replace it with a coin battery but this will do for now.

At this point I reassembled the machine and powered it on. and from what I could tell it was booting. The Power led turns from red to green and Hi RESQ led comes on. Turning the machine off with the soft on/off buttom the green led flashes several times them goes red. A VERY good sign! unfortunately my SCART cable hadn't arrived so I couldnt verify if anything was on the screen.

Cable finally arrived. I'm running the Scart cable though my OSSC scan converter to a DELL 2007FPB

and she is in fact alive! Message reads "Unable to book from disk. Set the correct Disk"

This is as far as I got with this machine. Inserting a disk it would spin for a bit then eject it back out on both drives, I tried cleaning the heads, recapped both drives etc with no luck. The heads would just sit there and didnt look like it was even trying to seek. Without a working drive I was reluctant to take it any further. 

Thinking what are the chances both drives could be bad I thought the fault may be on the Peripheral board however no luck there even after changing the NEC flopper controller chip and SED9420AC CMOS data separator IC still nothing. At this point I made the decision to buy another junk machine for parts.

Writing Floppys.

I used 2 different Retro PC in m y collection, a 1500mhz P3 and a 386 DX40 with 5 1/4" disk drives to write x68000 disks using Omniflop on Win XP and Xfloppy on Win 98 and 95. I had doubts because I didnt have any original disks to verify if it was the issue the drive wasnt reading however I can confirm both programs work fine.

No point going over this as it's already well documented.

https://gamesx.com/wiki/doku.php?id=x68000:writing_floppies

 

A lot of images are in the DIM format and will need to be converted to a raw format XDF. I recommend vf011010

https://nfggames.com/X68000/index.php/PC_Tools/Disk/?upload=1

Disk Drive Status LED board

For what ever reason the LED indicator board was removed form this machine. 0 drive is supposed to flash green when no disk inserted then solid green when inserted and changed red when read/writing.

I basically just made my own from some veroboard, 2 x 3 pin Red/Green LED's (3 colour) and Micro JST 2.0mm 3 pin connectors.

I'll leave it here for now 🙂

[Arcade King]

x68000 no 2 repair.

I bought a second machine from a Japanese proxy site for a very good price. I wanted this machine primarily as parts and Floppy Drives.

I didn't want to start tearing down the Floppy Drives from the first machine until I had a working unit.

Replacing the power supply and turning on the machine it was dead. 😞

Overall very clean board set without the factory hacks of the earlier revision.

Unfortunately as previously discussed the OG x68000 model had a 3.6 volt NiCAD rechargeable battery which leaks when discharged right next to a pair of oscillators and reset circuit. We've all experienced this one time or another with retro gear.

Somebody has already done some work replacing the oscillators with Epson programable ones and replaced the battery.

On both these machine's I will eventually install a lithium battery holder and battery probably a CR2450 like in later models.

As previously stated the machine was dead, No life from the CPU what so ever and Rom outputs were dead.

Hitting the reset button I would get some activity from the cpu but machine still didn't boot.

These OG models seems to be generally reliable so I'm going to focus on the power on reset circuit.

 

Using the working machine as a guide I quickly found IC77 the voltage supervisor/reset chip TL7705 was bad. I didn't have any on hand so I pinched it off the working board for now.

The outputs  Pin 5 and 6 were now behaving like they should however the machine was still not booting and Pin 18 on the 68000 cpu was still sitting high. Powering the machine on the reset should sit low for a second then come high.

Hitting the reset button resulted in a sync signal to the monitor which was a good sign.

Found a track broken between Pin 5 of the TL7705 and Pins 4 and 5 of IC 64 (74ls08) which in turn goes to the CPU's reset pin (18)

Machine now boots! however, no blue

Fortunately the solution was simple.

There are 3 pots to adjust the colour sitting in the upper right hand corner of the board, Blue was the pot on the right right next to the video out header.

Success, 2 working OG x68000's

I managed to get the floppys working on all machines. I'll eventually do a post dedicated to the Sharp 5 1/4" floppy drives.

[Arcade King]

I recently aquired a 1MB upgrade board for the OG X68000 above.

This bring the machine to 2MB which is the minimum required to expand the memory further using RAM expansion cards in the I/O slots at the back. 2MB is the minimum required to run most games.

I forgot to take a pic of the board installed. I'll add it next time I open the machine.

I also installed a CR2450 coin battery holder in this machine and mounted it on a piece of veroboard and stuck it on using Gorilla double sided tape.

Thanks for the suggestion @pocketmoney

 

[Arcade King]

X68000 Expert HD

Picked this one up from Yahoo Auctions Japan listed as "Junk". The same seller had 3 others listed at the same time all saying they were put into storage and hadnt been turned on since.

This model has 2 megs built in and a 40 Megabyte SASI hard drive.

This one arrived with 2 disks stuck in the drive.

As per the other 2 before even attempting to power on I upgraded the PSU to a Pico ATX.

Main CPU board side. I/O slots in the top right under the cover and bottom right is the video output module which can be removed.

Floppy drives at the bottom right, "Tetris" style PSU in the top left and SASI 40 Megabyte hard drive in top right. VERY neat design change to the OG model to fit everything in there without changing the case design.

40 mb SASI drive...Still working!

Main CPU board.

This is pretty much a all in 1 board as opposed to the OG x68000. All the video hardware that was on a seperate board is now on the main CPU and the Video output circuitry has been moved on a seperate board.  The battery has been also removed from this board to the Peripherals board.

The Peripheral board. Pretty much the same as the OG model except the battery that was on the main CPU board has been moved here. Battery is a CR2450, I replaced it with a CR2430 I use in System 3 Gottlieb Pinballs for the time being.

From what I can tell, the Expert / Expert HD was the first to use a coin battery, all previous models used a rechargeable Nicad which leaked when they went dead.

For what ever reason I can't find the pics of the PSU rebuild but I used the above board that was specifically made for the "Tetris" style psu's

This is the board populated taken from one of posts above installed in a OG housing, I ended up designing my own board for the OG model.

I'll replace this pic next time I open my Expert HD.

Not really much more to say on this one, installed the psu and the machine fired right up 🙂

Heres a pic of the disks that were left in the drives.

Nobunaga's Ambition Haoden?

Needless to say this disks don't work in fact they screwed up the drives on my other x68000 which then needed to be stripped down and re-cleaned.

Thats 3 for 3 x68000 now 🙂

 

[Arcade King]

It's been awhile since I've updated this thread. There's certainly a lot of stuff I would have liked to cover first like floppy drive servicing but seeing as I had a heap of soldering to do, I thought I'd get stuck into the ram expansion now that I've finally collected all the parts.

The project is called Galspanic and is a ram expansion board for the Sharp x68000 which can potentially expand the system to it's maximum 12 megabytes.

You'll need a TSSOP adapter to program the ATF22V10C-10XU Gal and a programmer capable of doing the job.

Most expensive part is the CY62167E SRAMs. You'll need the 5 volt variant not 3.3v. Back in June I purchased 10 CY62167GN-45ZXI at $20 a pop! They seem pretty hard to get so I didn't procrastinate.

Lastly you'll need a x68000 with 2megs of base memory.

https://github.com/stas2k/galspanic

Unpopulated Board.

I decided to start of with 2 chips (4 megs) which gives you 6 megs of total system memory which realistically is more than enough to play 99.9% of games from hard drive.

*IMPORTANT*

Due to a mistake in the V2 board design you need to cut the trace on the 1MB pad between off and the center pad and jump a wire from pin 1 of the GAL (DTACK) to the center pad as per the pic above.

The 4,6,8 and 10 MB jumpers correspond to the amount of ram installed on the board NOT overall system ram.

In my case I have 2 chips installed (4Mb) so jumpers 6,8 and 10 need to be cut and soldered to the "off" position. 

Installed in my OG X68000

This machine now has 6 megs! I'll upgrade my Expert to the full 12mb just for shits and giggles.

Ghouls n Ghosts

Strider

6 megs is more than enough to play all the best games! I've been waiting months for this.

I'm going to leave the thread open now. When I finally get around to updating the thread I'll edit a previous post and add content.

[alessiman]

3 Holy Grails!

Would you ever consider making up other Galspanic Memory Cards?  I have an OG X68000 here in Melbourne with only 2 Meg of installed ram 

[Arcade King]

4 hours ago, alessiman said:

3 Holy Grails!

Would you ever consider making up other Galspanic Memory Cards?  I have an OG X68000 here in Melbourne with only 2 Meg of installed ram 

Possibly the one I've already made up I could sell. I've got 4 blanks left.

My intention was to make a card for all 3 of my x68000's.

I'd love to see your machine if you don't mind posting some pics. It's rare to see another AAer with the retro PC bug.

[alessiman]

1 hour ago, Arcade King said:

Possibly the one I've already made up I could sell. I've got 4 blanks left.

My intention was to make a card for all 3 of my x68000's.

I'd love to see your machine if you don't mind posting some pics. It's rare to see another AAer with the retro PC bug.

Where do i start with the Retro PC's!  besides the X68000 i have an FMTowns, An MSX 1 and MSX 2, Sinclair, Oric, Atari, Amiga, TSR-80, Spectravideo and numerous other machines. 

Here are some images.  It came with 2Meg of RAM installed as well a SCSI2SD.  The unit has been converted to run off 240V but unsure if its a PICO PSU

I did pick up a 4 Meg card for the unit but its causing all sorts of issues

https://nfggames.com/forum2/index.php?topic=7246.0

But for now.  Here are some pics! 

[Arcade King]

On 01/10/2023 at 3:20 PM, Arcade King said:

It's been awhile since I've updated this thread. There's certainly a lot of stuff I would have liked to cover first like floppy drive servicing but seeing as I had a heap of soldering to do, I thought I'd get stuck into the ram expansion now that I've finally collected all the parts.

The project is called Galspanic and is a ram expansion board for the Sharp x68000 which can potentially expand the system to it's maximum 12 megabytes.

You'll need a TSSOP adapter to program the ATF22V10C-10XU Gal and a programmer capable of doing the job.

Most expensive part is the CY62167E SRAMs. You'll need the 5 volt variant not 3.3v. Back in June I purchased 10 CY62167GN-45ZXI at $20 a pop! They seem pretty hard to get so I didn't procrastinate.

Lastly you'll need a x68000 with 2megs of base memory.

https://github.com/stas2k/galspanic

Unpopulated Board.

I decided to start of with 2 chips (4 megs) which gives you 6 megs of total system memory which realistically is more than enough to play 99.9% of games from hard drive.

*IMPORTANT*

Due to a mistake in the V2 board design you need to cut the trace on the 1MB pad between off and the center pad and jump a wire from pin 1 of the GAL (DTACK) to the center pad as per the pic above.

The 4,6,8 and 10 MB jumpers correspond to the amount of ram installed on the board NOT overall system ram.

In my case I have 2 chips installed (4Mb) so jumpers 6,8 and 10 need to be cut and soldered to the "off" position. 

Installed in my OG X68000

This machine now has 6 megs! I'll upgrade my Expert to the full 12mb just for shits and giggles.

Ghouls n Ghosts

Strider

6 megs is more than enough to play all the best games! I've been waiting months for this.

I'm going to leave the thread open now. When I finally get around to updating the thread I'll edit a previous post and add content.

Just an update on the Galspanic ram expansion board.

I've been tinkering in Kicad on this board. I wanted to play around with autorouting so I though this would be a great project to edit and fix the issues.

I manage to find the older 1.2 version of the board on github which used buffers and a DIP gal to study the pcb and schematics.

Pic of Rev 1.2 and the GAL pin assignment. Take note  of MSK (13) and DTACK (20).

This design is limited to 8 megs of SRAM.

 

and here is 2.0

Those will a keen eye will noticed Dtack is on pin 1 which is a input and MSK is on an I/O pin. They should be the other way around. CEM 5 was added to enabled the extra SRAM for a max of 12mb, 2 on machine and 10 on card.

As far as I can tell MSK which is tied to J1 a jumper pad is reserved for 1MB X68000 machines, however this hasnt been implemented in the GAL's fuse map so essentially does nothing.

My revised version does away with MSK and J1 and moved DTACK to the correct pin.

So here my revised board.

UPDATED 2/11/2023

Changes in Rev 2.2.1 from 2.0

1. Removed MSK and J1. I think its completely impractical considering this design uses a SMD GAL so its not like you can easily take it out and play with the fuse map. Pin 1 is now grounded.

2. Moved DTACK to Pin 23 and corrected the mistake in Rev 2.0

3. Changed the closed jumper pads to open so no need to cut the traces when using less than the max amount of ram.

4. Added 74AHCT1G07QSE-7 non inverting buffer into the DTACK line. It's been suggested that adding other boards into the system using DTACK could cause issues. All unconfirmed mind you but doesnt hurt adding this in.

Full credit goes to stas2k who original created the board. I don't know how GITHUB works in regards to adding open source revisions so I'll just post it here for now.

JLCPCB options

•     PCB Thickness: 1.6
•     Surface Finish: ENIG-RoHS
•     Gold Fingers: Yes
•     30° finger chamfered: Yes

JED for the Gal can be downloaded from Github.

Please note this revision as of 02/11/23 is untested so use at your own risk....it should be fine though. I'd like to get 5 made up asap...it is a shame to waste the remaining 4 blanks 😞 Geting them made up in ENIG with gold chamfered fingers is expensive.

I'll also create a version using a DIP 22V10 GAL. I'd like to easily be able to play around with the fuse maps for stock 1Mb x68000's and mush easier to program without needed special adapters. I'm also considering extending the board to make it easier to remove.

galspanic.kicad_pcb_v2.2.1.zip

galspanic._gerber_2.2.1.zip

 

[Arcade King]

Here's my final "hybrid" design for this Galspanic project.

This is my ideal version of the Galspanic ram expansion board v3.0

Changes.

1. Larger footprint for easy installation and most importantly removal. Yeah at the time of posting this it costs $10 AUD more per board but I don't care. It's about the same footprint as the midori midi interface board. When I was testing and working out the DTACK bug in the v2.0 board, I had to tear the side off the machine so I could easily remove the smaller board...Very annoying.

2. Reverted back to a DIP 20V10 Gal and added back the MSK jumper pad which is tied to ground. Did this for 2 reasons, easier GAL to source than the TSSOP SMD 20V10 and can be removed if somebody wants to play around with the GAL equations. I think part of the original designers goal was to make these work on a stock 1mb x68000. He never got as far as to writing the equations for the GAL to implement this, I honestly don't know if it's even possible. All ram expansions, old or modern require the machines base memory to be upgraded to 2MB. The MSK jumper looks like it was implemented to select how much base memory you have but as I mentioned above it's not implemented in the fusemap for the GAL.

3. Kept the open jumpers I implemented on v2.1 for 4, 6, 8 and 10 MB.

4. Lastly added a giant X68000 logo just because.

I'm getting 5 boards made up for personal use via JLCPCB so I'll update the thread and make the gerber files available once I've tested it for those who want to have a go making one themselves.

 

 

[Berty]

Very cool. I've wanted an X68000 for years and years but I've been put off by the cost of the more highly spec'd machines. I'm going to YAJ right now...

[Arcade King]

4 minutes ago, Berty said:

Very cool. I've wanted an X68000 for years and years but I've been put off by the cost of the more highly spec'd machines. I'm going to YAJ right now...

I think its a good time to buy considering the AUD is almost on Par with the yen. I guess thats why so many people are going for holidays over there now.

[Berty]

8 minutes ago, Arcade King said:

I think its a good time to buy considering the AUD is almost on Par with the yen. I guess thats why so many people are going for holidays over there now.

What do you reckon about the X68030? I hear that there are some compatibility issues, but I don't know how material those issues are. 

[Arcade King]

24 minutes ago, Berty said:

What do you reckon about the X68030? I hear that there are some compatibility issues, but I don't know how material those issues are. 

I'd avoid. stick to something thats reliable unless you got money to burn. I think the XVI is probably the best over all because you can switch between 10 and 16 mhz however it has the same sorts of issues as the x68030 with leaking SMD caps so you'll want to make sure its working.

With the OG models you can get them cheap but its a gamble with the battery. I'd probably recommended getting a EXPERT and above, they started using lithium coin battery's at this point. Super and above have full SCSI compatibility which gives you a wider choice with SCSI emulation devices however I highly reccomed BLUESCSI or PiSCSI, both support SASI for older machines. I'll do a write up on these eventually.

I will be selling one of my OG models at some point if you want somthing you can plug in and play 🙂

[Berty]

I might take you up on that.

[Arcade King]

Here's my final version of the GalsPanic ram expansion board v3.1.1

There is a new board some genius had made with ram expansion and midi interface in one board. Seeing as I've already had some midori midi interface boards made and put many hours into the Galspanic update I continued on this route.

I wasn't happy with the first revison of my hybrid board so chucked it in the bin 😞. People had commented that the original design by stas2k should have a line buffer for the DTACK line to prevent issues with other boards installed for example a midi interface, so this is exactly what I've done.

Most changes are the same as the cut down 2.2.1 version.

Changes in Rev 3.1.1

1. Added back in J1. Not really needed however could be useful if the implementation of the ram upgrade is possible on a stock 1MB machine. When I get time I'll have a play with the GAL equations and see if it's possible.

2. Moved DTACK to Pin 23 and corrected the mistake in Rev 2.0

3. Changed the closed jumper pads to open so no need to cut the traces when using less than the max amount of ram.

4. Added 74AHCT1G07QSE-7 non inverting buffer into the DTACK line. It's been suggested that adding other boards into the system using DTACK could cause issues. All unconfirmed mind you but doesnt hurt adding this in.

5. Made the board larger for easy removal, this adds about $10 AUD on per board. If you want to save money use the compact 2.2.1 above.

6. Decided to use the DIP 22v10 GAL instead of the SMD ATF22V10C-10XU Gal. There were several reasons for the change.

• Cheaper and easier to obtain. I'm currently using a common Lattice GAL22V8D-15.
• Easier to program, no adapter required and makes it easier to reprogram if you want to play around with the fusemap.
• Runs much cooler...the GAL is not even slightly warm after an hours use.

Now I've tested it with 4 megs I'm going to fully populate the board to the full 10 megs for a total of 12 MB.

I'm not going to bother putting this up on Github as I made this revision for myself but happy to share the files so other can do the same.

JLCPCB options

•     PCB Thickness: 1.6
•     Surface Finish: ENIG-RoHS
•     Gold Fingers: Yes
•     30° finger chamfered: Yes

JED for the Gal can be downloaded from Galspanic Github page.

 

galspanic.kicad_pcb_v3.1.1.zip

galspanic.kicad_pcb_v3.1.1-gerbers.zip

 

[Arcade King]

I decided to fully populate a board to the full system memory of 12 megabytes. I'd only reccomed 6MB if you want all games to run off hard drive.....and you will 😉

Warning, only attempt hand SMD soldering if you are complete masochist like me.

 

Tested and working 100% This one is going in my x68000 Expert.

I also modified the PLD equation file to WinCUPL. I'm far more familiar with that format than GALasm from my Berserk project.

Well all 3 of my Sharp x68000's are now fully upgraded with ram expansions. Next project will be the Midori midi interface card.

Galspanic WinCUPL.PLD