Author Topic: Original 68000 - Does not seem to boot.  (Read 5229 times)

Offline BlueBMW

  • MassiveMember
  • ****
  • Posts: 444
Original 68000 - Does not seem to boot.
« on: April 27, 2012, 02:03:34 pm »
New question:

I'm not entirely sure where to start, but I have this original 68000 machine here (early launch model) and it will turn on, but not seem to do anything.  It will not display anything on a monitor, nor will it read floppy disks.  I have confirmed that the PSU is at least supplying the correct +/- 5v and +/= 12v.  I've also tested the floppy drives and they work great on another system.

Any ideas what to look at first?



Original question I asked in this thread has been answered by me.  The original 68000 floppy drives additionally have a 5V standby line.  You can eject disks etc even while the system is off...

I'm attempting to replace a power supply in an original 68000 machine using the guide on gamesx.  I have one issue though.  The floppy drives on this system have a different connection than on other 68000 machines.  They have a four pin connector with four wires.  Based on color, it would appear the 4th wire is a 5v stby signal, but that seems odd to me.

Anyone know what the pinout on these floppy drive power connectors is?






« Last Edit: April 27, 2012, 03:47:17 pm by BlueBMW »

Offline lydux

  • MassiveMember
  • ****
  • Posts: 238
Re: Original 68000 - Does not seem to boot.
« Reply #1 on: April 27, 2012, 09:43:28 pm »
This model interest me... Is there any way you could post a good quality picture of the mainboard ?

What about the front leds when power plug it on and turn it on/off ?

Offline Lawrence

  • Runs the place
  • Administrator
  • ThrobbingMember
  • *****
  • Posts: 3331
    • NFGgames
Re: Original 68000 - Does not seem to boot.
« Reply #2 on: April 27, 2012, 09:49:07 pm »
It sounds like you have a capacitor problem, I have a similar issue with my XVI Compact.  Basically, the caps are leaking and it prevents the computer itself from properly controlling the power (mine will turn on, go through the shutdown motions and never actually power down).  Have a look around the mainboard for caps that are leaking, the fluid from them will wreck your motherboard so it's sort of critical. 

Offline BlueBMW

  • MassiveMember
  • ****
  • Posts: 444
Re: Original 68000 - Does not seem to boot.
« Reply #3 on: April 27, 2012, 10:16:30 pm »
It sounds like you have a capacitor problem, I have a similar issue with my XVI Compact.  Basically, the caps are leaking and it prevents the computer itself from properly controlling the power (mine will turn on, go through the shutdown motions and never actually power down).  Have a look around the mainboard for caps that are leaking, the fluid from them will wreck your motherboard so it's sort of critical. 

This model uses leaded caps and not the SMT ones like on the compact I've got.  So far I dont see much leakage, but being from 1987, I suppose these caps are probably done anyways.

When powered on, the power led turns from red to green and the High Resolution LED comes on.  The floppy drive lights turn on, and they will accept disks, but not read them.  No video signal seems to be coming out of the system as my monitor never turns on, just stays on standby as if it has no video signal.  When powered down, the system will just sort of hang, even pressing reset wont get it to shut down.  I have to flip the power switch.

I did verify that the PSU is producing +/- 5V and +/- 12V   Thats also how I confirmed that the floppy drives additionally have a 5V standby line to them.  I guess its so you can load / eject floppy disks without turning the system on to do so.

Here's all the pictures I've taken of the unit, I'll try and make some high quality scans of the boards etc tonight.  The unit is fully disassembled right now.




















Old NiCd battery removed,  not too much corrosion, but something to clean up a bit.



I tested the floppy drives by basically connecting the floppy cable to another system but using this system to power them.  They work great!





Offline lydux

  • MassiveMember
  • ****
  • Posts: 238
Re: Original 68000 - Does not seem to boot.
« Reply #4 on: April 27, 2012, 10:49:54 pm »
As i thought !

You got the one with two eprom socket filled, they maybe faulty. And if not, they may contains a special IPL version that we do not have a dump. Got an eprom reader/writter ?

Offline BlueBMW

  • MassiveMember
  • ****
  • Posts: 444
Re: Original 68000 - Does not seem to boot.
« Reply #5 on: April 27, 2012, 11:44:01 pm »
As i thought !

You got the one with two eprom socket filled, they maybe faulty. And if not, they may contains a special IPL version that we do not have a dump. Got an eprom reader/writter ?

Ive got a chip reader / writer so ill see what i can get out of them!

Update:

I pulled the two eproms and read them out.

They are MBM27C512-25 eproms labelled IX0897CE V1.0 and IX0898CE V1.0

When I read them out and saved the buffer I ended up with two 64kb bin files.  Hopefully this is what you guys need.  I dont have much experience dealing with eproms and the like.

http://www.mediafire.com/?329mroir36kftfa
« Last Edit: April 28, 2012, 09:41:33 am by BlueBMW »

Offline lydux

  • MassiveMember
  • ****
  • Posts: 238
Re: Original 68000 - Does not seem to boot.
« Reply #6 on: April 30, 2012, 03:49:29 am »
Ok ! Thanks for this dump and pictures BlueBMW.

Time to analyze this things. These 2 dumps are useless as is. Here is why :
Basically, an m68000 based system works like this : the cpu have a 16bits data bus (pins D0-->D15), and so will fetch 2 bytes at a time from its address space.
You have 2 eproms, which  are 27c512. These eproms are each 512*8bits in data width (D0-->D7) and 512/8=64KBytes.
So, 1 eprom is hooked to the lowest part of cpu's data bus (D0-->D7), and the other eprom, to the highest (D8-->D15).
When the cpu access the rom space, it will get/set 1byte from/to the first eprom, and the next byte from/to the second eprom.
That it, the eprom mark IX087CE_V10.BIN contains EVEN bytes of IPL, and IX0898CE_V10.BIN contains ODD bytes.
Make sense ?

Now, you have to merge these together to get your full exploitable 128KB IPL.
I've uploaded on the file archive : http://nfggames.com/X68000/Uploads/BIOSCZ600.zip

You can try it under XM6, it will work (and as concequence, indicate that your problem is not here...) and does look like the same as the widely known iplrom.dat.
But deeper in code inspection give me a lots of differences. I don't know if the dump is good or not (we need a dump from another CZ600 to confirm this), but this IPL is diffinitively a different one.


Anyway, back the topic.
I have two ACE which suffers of the same symptoms as yours (I hope this is not the case... as I haven't found a solution yet)
Here is some pinouts you can test on the cpu to verify the working conditions :
- CLK (pin 15)
- #RESET (pin 18)
- #HALT (pin 17)
- #BR (pin 13)
- #BG (pin 11)
- #IPL0 (pin 25)
- #IPL1 (pin 24)
- #IPL2 (pin 23)


Offline BlueBMW

  • MassiveMember
  • ****
  • Posts: 444
Re: Original 68000 - Does not seem to boot.
« Reply #7 on: May 01, 2012, 03:14:20 pm »
I'll do some probing on the 68000 and see what I get.  Looks like I may have another junk original 68000 coming in.  Might take 6 weeks to get it though.  Once I do, I'll dump its chips so we can compare the two.

Offline BlueBMW

  • MassiveMember
  • ****
  • Posts: 444
Re: Original 68000 - Does not seem to boot.
« Reply #8 on: May 08, 2012, 02:57:47 pm »
I just got a second Original 68k system in.  Fortunately, this one works perfect!  So I'll start swapping boards / parts until I find the faulty piece in the other system, then diagnose from there.  Also, I'll dump the eproms from this system so we can compare them to the ones in my other system.

Offline Artemio

  • SmallMember
  • **
  • Posts: 21
    • The Policenauts Translation Project
Re: Original 68000 - Does not seem to boot.
« Reply #9 on: October 16, 2016, 05:44:01 pm »
I know this is deep necroposting, but I got another dump from a X68000 CZ-600CE. Mine is named RH-IX0898CEZZ.

Here is the dump:

http://junkerhq.net/cps2/x68000/RH-IX0898CEZZ.zip

A photo of the MB:

http://junkerhq.net/cps2/x68000/x68000_CZ-600CE.JPG

And romcmp throws this when compared to BlueBMW's one:

RH-IX0898CEZZ.ic12            IX0897CE_V10.BIN            99.992371%
RH-IX0898CEZZ.ic11            IX0898CE_V10.BIN            99.990845%

with -d

RH-IX0898CEZZ.ic11 [1/4]      IX0898CE_V10.BIN [1/4]      IDENTICAL
RH-IX0898CEZZ.ic11 [2/4]      IX0898CE_V10.BIN [2/4]      99.975586%
RH-IX0898CEZZ.ic11 [3/4]      IX0898CE_V10.BIN [3/4]      IDENTICAL
RH-IX0898CEZZ.ic11 [4/4]      IX0898CE_V10.BIN [4/4]      99.987793%

RH-IX0898CEZZ.ic12 [1/4]      IX0897CE_V10.BIN [1/4]      99.987793%
RH-IX0898CEZZ.ic12 [2/4]      IX0897CE_V10.BIN [2/4]      99.987793%
RH-IX0898CEZZ.ic12 [3/4]      IX0897CE_V10.BIN [3/4]      99.993896%
RH-IX0898CEZZ.ic12 [4/4]      IX0897CE_V10.BIN [4/4]      IDENTICAL




Offline kamiboy

  • ThrobbingMember
  • *****
  • Posts: 542
Re: Original 68000 - Does not seem to boot.
« Reply #10 on: March 12, 2017, 02:24:48 am »
Yo, blue, still around? I just got an OG X68000 in with the exact same symptoms as yours back from 2012. If you remember the results and conclusions of your board swapping experiments I'd love to know.
« Last Edit: March 12, 2017, 07:41:08 am by kamiboy »

Offline kamiboy

  • ThrobbingMember
  • *****
  • Posts: 542
Re: Original 68000 - Does not seem to boot.
« Reply #11 on: March 12, 2017, 07:50:54 am »
For the record, there was another thread here about repairing OG X68000 units. Well, as the author of that thread mentioned the problem with these OG's seems to be the 69mhz crystal, and I have a theory as to why.

You see, these crystals are situated right next to that notoriously problematic nicad battery. These things leak, and I am guessing, take out the oscillator right next to them. When I soldered mine out I saw a cake of leakage on its underside extending, I pressume, to the inside of the crystal can, doing only gaming gods know what.

I borrowed a crystal from an ACE and presto, it came to life. The OG has other problems though. It cannot shut down, so it is on all the time, and the video flickers whenever the floppy drive reads.

I've already exchanged all the caps on the PSU, so perhaps the other caps need servicing to fix the other issues. It is perfectly capable of playing games right now though.