CPC6128 mod.

[Bryce]

Hi All,
   It was a long weekend here in Germany. Four days off in a row, but MrLou made sure I didn't waste my time hanging around pubs or the like. He'd sent me his latest "challenge". Not as major as the 464+ mod, but I thought I'd document it here anyway. Standard CPC6128, the mod is to install a MegaFlash internally and replace the 3in drive with a HxC, but the RevF version in this case.
First off, the internal expansion connection. It's an edge connector version. This makes it easier or at least neater to add an internal expansion port, because it has all the expansion port pins available as unused holes on the PCB. You can see them here. They're usually filled with solder, so you'll need to remove that first like I've done here.


[attach=2]


To solder the flat cable you need to split and strip every second wire and solder the rear ones first. It's a pain in the arse and takes ages, but there's no easy way.


[attach=3][attach=4]

With a 90° fold it sticks out the right side where I've attached a 50 way header and there's quite a bit of space for expansions to be located here.

[attach=11]


Under the PCB there are quite a few sharp pins. There's lots of space, so they shouldn't really be a problem, but the capacitor pins are rather long and sharp, so cut them back a bit in case they end up poking through the flat cable and causing a short.
The next stage was a bit more difficult than I was expecting. I'm not sure whether I should call it a "Guide" or a "Warning". I had suggested to MrLou that the RevF version might be better to install in a CPC than the RevC. The main reason being that the display is tiny compared to the RevC version and allows space for the display, buttons, LEDs and SD Slot in the space the front plate needs. It also comes in a nice frame that I thought might fit nicely in the CPC. I was wrong.
First off my apologies to Jeff and Lotharek, this is by no means critical of your device. The RevF is perfect for what it is designed to do. What I've done here is tried to hammer it into a place it was never designed to be. You may prefer to look away during some of this post
The first problem was obvious: It doesn't fit, it was never meant to. So things had to go. I wanted to edit the CPC as little as possible, so the HxC was going to have to take a beating. But some bits of the CPC still had to go.

[attach=5]

The 3in drive has two posts on the left. The rear one would be under the HxC PCB, so it had to go. The front one happens to be in front of the PCB, so I "edited" the metal frame so that I could even make use of the post/screw to mount the HxC. To do this I needed to cut the metal to form a tag and raise it to the level of the post, then I added a hole to fix it like the original drive was.

[attach=6]

Note: This frame is made of bloody hard stamped steel. It's extremely hard to cut, almost impossible to drill and extremely sharp when you've modified  it. In fact after doing all these changes I now know how Steve McQueen felt in that final scene of the Great Escape: http://theselvedgeyard.files.wordpress.com/2010/02/js1565847.jpg you can cut yourself to threads doing this.
Another warning: The two holes on the side of the frame fit exactly to the side screws of the CPC, BUT they're not threaded! I completely sheered an original CPC screw finding this out Got out my threading kit and fixed that, but it was still annoying. Are the current HxC RevF still like that or has that been rectified? It should be M3 0,5mm for anyone who needs to know.

[attach=7]

The next problem was the top left corner. The CPC case drops to the keyboard level right after the drive, so the case hits the HxC and this corner had to go. Out with the hacksaw again and this was solved too. Now it all fits nicely in place and is even mounted using 3 of the 4 orinigal screws.

[attach=8]

Next up was making a faceplate. I used the case of a DVD to make this. The plastic is a bit thin, but easy to work with and very close to the original drive plastic. I cut a piece the size of the 3in drive and glued it in place. Cutting the holes was easy as I had a perfect metal stencil so no measuring was required.

[attach=9]

After putting it all together and trial fitting it a new problem became obvious. The buttons aren't long enough to poke through the plastic. On top of that, they're red! That definitely wouldn't be MrLous first choice. So they had to be longer and black. The three buttons are soldered on the lower side of the PCB. They're SMD parts. I had some similar parts here with a longer shaft in black, so I swapped them out.
Next warning: The PCB is soldered with Lead-free solder, if you are swapping parts and using leaded solder, remove the entire solder from the pad before you re-solder, don't mix leaded and unleaded, it will fail pretty quickly.
Anyway, after that I swapped the pinout of the power connector to the drive and made an adapter cable to connect the drive, this one: DIY:Floppy Drives - CPCWiki and gave it a quick test (ended up playing Gauntlet for over an hour).

[attach=11]

So this is what it looks like at the moment. I still need to install the read/write switch for the MegaFlash and the write LED. I'll do that later this week when I have time.

There's actually enough space above the HxC to add a slimline 3.5in drive, so it would be possible to have A: and B: (HxC and 3.5in) within the space of the 3in drive

Bryce.

[mr_lou]

This is awesome!
Great work!

Sorry that it's been so troublesome.

But we all know you like a good challenge. 
(especially when it's over  )

[Bryce]

It was extremely time consuming, but I'm pretty happy with the results so far. The fact that it retains the metal frame and uses the original mounting points make it really robust and keeps the CPCs case rigid like it should be. There's also no give / pushback when you press the buttons, so it feels pretty solid too

Bryce.

[Kris]

Nice job !
About the megaflash, what about the deport of the switches upper the case of the CPC to avoid open/close CPC each time you want to set up a new rom ?

[Bryce]

The read/write switch will be mounted at the back of the CPC as a black sliding switch, so opening the CPC won't be necessary. The LED will also be visible but well hidden The ROM0 and ROM7 switches will be left inside as MrLou will rarely or possibly never use these.
If you look at the picture above, you'll see that the MegaFlash doesn't have the read/write switch or LED on the PCB.

Bryce.

[Kris]

Sounds good ! 

[TFM]

Very nice project. 

[Bryce]

I had time to do some hardware today, so as well as fixing a pile of stuff from Beaker, I also had a chance to get some more of this 6128 done. I've added the read/write switch at the back of the CPC. I used a black sliding switch and even sank the screws to keep it neat. I also decided to make the write LED as good as invisible (MrLou likes discrete). I used a 5mm flat LED which I tappered and installed in one of the cooling slots, so in write mode the grill glows red, when it's off you'd never notice it was there. I've also removed the original LowerROM/ROM0 and replaced it with a socketed EPROM with the patched version that scans all 32 ROMs.

Here's a few pics.

Bryce.

[beaker]

Damn, that looks all sorts of fine 

[dcdrac]

it looks great and over time as the mechanical parts of the old floppy drives fail to me the way to go.

[beaker]

True, I am using SD card solutions where I can, SD2IEC, Turbo MMC, 2x HxC, MegaEverdrive, Super Everdrive, Turbo Everdrive. The only thing I wonder is what happens when SD cards become obsolete?

[Bryce]

SD cards have a long life ahead of them and even their successors, the mini SD can be used with an adapter.

Bryce.

[Gryzor]

Just... wow. How much do you charge man?

[Bryce]

Depends what you want

Bryce.

[Gryzor]

Less than you could imagine, probably... everything crammed in, probably plus a Pi with proper outputs that patches into the CPC's keyboard (ok, that's taking it too far)

[Bryce]

I've been taking a look at the "keyboard question" lately. There were some posts lately asking how to connect a PS/2 keyboard without having to add a pcb crammed full of ICs. I think there are easier solutions than the current ones, so I've added it to my "possible projects" list. So it might get built later.

Bryce.

[ralferoo]

To solder the flat cable you need to split and strip every second wire and solder the rear ones first. It's a pain in the arse and takes ages, but there's no easy way.

Couldn't you have just used an IDC socket and just pressed a header onto the cable?

[Bryce]

Couldn't you have just used an IDC socket and just pressed a header onto the cable?

Unfortunately not. The pin rows are 5mm apart as the were meant for the Schneider Centronics header. Any IDC headers I know of need a 2,54mm pitch.

Bryce.

[Bryce]

Couldn't you have just used an IDC socket and just pressed a header onto the cable?

Unfortunately not. The pin rows are about 7,5mm apart as the were meant for the Schneider Centronics header. Any IDC headers I know of need a 2,54mm pitch.

Bryce.

[wilco2009]

I like it!
It is a great project.
Thanks to Bryce for the detailed explanation.