x68000 Thread - Now with MIDI!

[vanpeebles]

Ok, sadly I lost all my old x68000 posts, both on my thread and the retro area. So I'll try and start again from the beginning.

Before Chrimbo last year, while browsing ebay for goodies, I picked up a Pro II Desktop x68000 on ebay for the price of a modern console, and very much enjoyed what it had to offer. It already had an ATX PSU fitted, came with some boxes of floppies, and also had a PS/2 keyboard adaptor plus a VGA adapter cable. I also picked up a RAM expansion, to take it from 2mb to 6mb.










That was the end of chapter one!

[vanpeebles]

Chapter two! While reading and posting on a special x68000 group, I got the chance of buying a large bundle of x68000 goodies, including a proper keyboard, mouse, boxed ram expansion, original manuals, original OS floppies, some spare parts, some loose floppies, and a load of boxed games, joypads etc.

It also came with a much sought after x68000 XVI tower model, which can run at 10mhz or 16mhz, sadly this was sold as not working, but the value of all the rest of the stuff, way out weighed the dead XVI.







Surely it was worth having a go at fixing it?!

[QualityChimp]

YES!

Both the thread and the X68000 rising from the ashes like a phoenix!

[Zaki]

Chapter two! While reading and posting on a special x68000 group, I got the chance of buying a large bundle of x68000 goodies, including a proper keyboard, mouse, boxed ram expansion, original manuals, original OS floppies, some spare parts, some loose floppies, and a load of boxed games, joypads etc.

It also came with a much sought after x68000 XVI tower model, which can run at 10mhz or 16mhz, sadly this was sold as not working, but the value of all the rest of the stuff, way out weighed the dead XVI.







Surely it was worth having a go at fixing it?!

Castlevania takes advantage of the 16mhz Hope you fix it pal.

[vanpeebles]

Castlevania takes advantage of the 16mhz Hope you fix it pal.

Give us time, I had to go for me tea!

So, I was hoping that the x68000 XVI was just suffering from the usual issue of a dodgy PSU. The modern fix is to convert it to an ATX PSU (far more reliable), but this needs a loom making, and also a small circuit board to handle the soft power on design. To start with I checked out what I had my working x68000.



And then set about making my own. I pulled the PSU to bits, and clipped out the cables, after making notes of what they were, and then following a wiring guide online for the XVI (all X68000s models are slightly different). There was signs of cap leakage all over the old PSU, and it looked knackered.





On the old PSU most of the lines were labelled on the PCB, to also check off. I made my own notes, and compared them to the old line guides.

I used an ATX extension cable, and also a molex power extension cable. Cut one side off, and soldered on my x68000 wires. I kept the drives on the separate molex.









I've never made a small circuit like that before, so it was a little rough in places, but I checked all my wiring for continuity using a beeper on a multi meter.

[vanpeebles]

Sadly this didn't fix the problem. Random lights came on, but nothing else. Although the floppy drives had power. I noticed that if I unplugged the motherboard cables then the switches, and lights worked fine. Next up it would be capacitor job. I started to dismantle the system, and began the task of listing all the capacitors in the system.



While all this was going on, I got carried away trying out all my new disks, and forgot to check them for disk mould, which grows on the organic media surface of 5.25" disks mostly. A noob error, and something I was already familiar with from BBC disks. I dirtied the heads on my working x68000. I had to source a 5.25" floppy cleaning disk on ebay, which got me back in action. To clean the disks properly, you need to move the media round by hand, and clean the window area with a cotton bud dipped in distilled water.

[vanpeebles]

I decided I would do the motherboard first, as that had only four caps, and the RGB module, as that had around 10. I left the I/O board which sits in the base, as that had a million of the damn things on. I'd leave that until last.

I started out on the RGB module, removing caps. Some of them snapped off leaving the tails in, which I just couldn't shift. I spent a lot of time wondering how best to shift them, heating needles to poke with, trying fine braid, trying the iron at a hotter temperature. By luck, I found my old model hand drill, called a pin vice, this had a tiny drill bit, which was just say small enough to go inside the metal rings on the PCB. So I gently drilled them out using hand power. While I was doing this, I noticed that the first three new caps, that I soldered in, where the wrong way round lol.



Just to add, it took hours, listing all the caps, and then finding them all on ebay. I went for high quality panasonic 105 degree capacitors. The day after, I went to remove some more caps, I forgot my iron was at the hotter temp from the day before, and I burnt a small ring track clean off the board. Using the maintenance manual found online. I repaired my error using some wire, running from the capacitor to where the trace was going on the board. All the time I checked my work for continuity, making sure, stuff did go where properly. My best friends were print outs of circuit diagrams.





Learning from my wrong doings, I also recapped the four the on the motherboard. By this time, I was a dab hand at dismantling the x68000, and reassembly. I could put it back together and dismantle again, with all the screws in the right places, time after time, Full Metal Jacket style.

So tentatively. With my big metal box ATX PSU, I powered it on, while trying to keep both hands over my ears, my face looking all >_<

0_< What's this, a normal power light, a CPU light? And a flashing floppy drive light searching for a disc. I reach for a game, and put Alien Syndrome in, the drive chugs into life and the music starts! Wow!

But!! I connected the display, and nothing, no display, not even a syncing effort from the monitor, it stayed asleep It was a case of really close and getting there, but not quite yet. Time to consider my next move.

Buoyed by this success, I was now a soldering world champion, and socketed the bios chips in both my Neos. Amazingly they both went perfect, de-solded lovely with my special silicone tip Japanese de-soldering pump, and when I soldered the socket in, I just had to look at the pins, and they soldered themselves flowing lovely.

[vanpeebles]

Once again I turned to the internet for answers, and it was suggested, that a small chip on the motherboard that handles some of the rgb signalling can fail. I ordered a replacement from ebay for £4 quid, had a bit of battle, but got the old one unsoldered, and the new one in. I checked off all the pins for continuity, against small testing points on the board, or the other end of the track where they were going. Everything looked ok, I was sure this was a winner.

I plugged it in, and before I could even turn it on, there was a high pitched whine from my PSU, and the system was totally dead, I'd gone from not working, to nearly working, now completely knackered, I was crest fallen. I took to the internet again, and some legend posted, that his did the same, and it was an incorrectly fitted RF shield, shorting out a line to earth.

Sure enough the 5 volt line, was grounded to the RF shield. I totally dismantled it (again), noticing that the motherboard wasn't clipped in properly, and this had caused the top flexible shield to flex a bit. I reassembled the whole, testing the earth at each step. Everything seemed ok, powered on, game ran again! Back to where I was, I tentatively connected the rgb/vga cable, and YES! A working picture, Alien Syndrome, was on and running. I let it run on a loop for a few hours, success!!

[Colin]

Top work Van!

[vanpeebles]

I'm now on the final straight, I switched from my external metal box ATX psu, to a small internal micro PSU, with external laptop style box, a lot neater. I broke out the hot gun glue, and glued up my little circuit board to make the wires safe.

I then cut up a broke old xbox 360 case, and glued that in to protect the PSU from shorting on the metal shielding. I glued the ATX socket to the plastic, and then glued in the adapter socket to the back of the case, using a free hole, with the original PSU not fitted.

[vanpeebles]

Next step is check the wiring on a home made looking vga to rgb cable, and compare that to my working one. Incase it was that which blew something. I also have a scsi2sd card thing to try out. Then it's time to enjoy some games on it.

I'm not sure what is extra on the 16mhz Dracula, I noticed that the annoying hidden secret block, which fires a ton of monsters, now runs flawless with no slowdown. Cotton also runs with no slow down.

[garrz32]

lovely machine, was looking at getting one a while back.Good job

[Zaki]

Great work Pebble!

All your posts reminded me of this

http://www.hakko.com/english/hikaru/pages/story1.html

[vanpeebles]

Hahaha, I love those stories. For my soldering, I used my Hakko, and after the early struggles I switched from a pointed tip to a small Hakko chisel tip.

[QualityChimp]

I love this thread!