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Amiga 2000 disk drive connector - broken pin

Amiga 2000 motherboard broken floppy connector pin interface

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#1 Nebulon OFFLINE  

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Posted Wed Mar 22, 2017 2:25 PM

Definitely my bad this time. Ugh.

 

Here's a great example why it's not a good idea to do hardware changes when you're in a rush. You know, by lifting the cage that houses the power supply and bays without first disconnecting the ribbon cable from the motherboard.

 

In the process I accidentally broke one of the pins off of the floppy drive connector on an Amiga 2000 motherboard. The pin is securely stuck in the end of the ribbon cable's connector.

 

Any advice on the best way to fix/replace the motherboard's connector?

 

I'm guessing that the cable itself is kaput, since I don't see how I can get the actual pin out of it.

 

Another question: It's been awhile, but I was pretty sure that PC and Amiga disk drive ribbon cables were the same. Is that correct?

 

Thanks!



#2 JamesD OFFLINE  

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Posted Wed Mar 22, 2017 2:28 PM

Definitely my bad this time. Ugh.

 

Here's a great example why it's not a good idea to do hardware changes when you're in a rush. You know, by lifting the cage that houses the power supply and bays without first disconnecting the ribbon cable from the motherboard.

 

In the process I accidentally broke one of the pins off of the floppy drive connector on an Amiga 2000 motherboard. The pin is securely stuck in the end of the ribbon cable's connector.

 

Any advice on the best way to fix/replace the motherboard's connector?

 

I'm guessing that the cable itself is kaput, since I don't see how I can get the actual pin out of it.

 

Another question: It's been awhile, but I was pretty sure that PC and Amiga disk drive ribbon cables were the same. Is that correct?

 

Thanks!

Test it.  If it works, it's the key to keep you from inserting the cable backwards.



#3 Nebulon OFFLINE  

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Posted Wed Mar 22, 2017 3:03 PM

Test it.  If it works, it's the key to keep you from inserting the cable backwards.

It doesn't seem like it's the key for the cable orientation. It appears to be broken. Keys like this that I've seen in the past have been plastic and not metal. Then-again, I suppose it's possible.

 

Based on another Amiga 2000 sitting here, there isn't supposed to be a missing pin on the Amiga 2000 motherboard floppy drive connector.

 

Unless perhaps there are some motherboard revisions on which they did remove a pin and place it in the cable. An odd practice though, since that you stop you from being able to move the cable from one revision to another.

 

Drives connected to that machine internally exhibit the same behavior (read for awhile, then stall out or error with a statement saying that the disk isn't there suddenly). All of the usual chips have been replaced (CIAs, Paula, Gary, 68000, Blitter).

 

I hope you're right about the key thing.


Edited by Nebulon, Wed Mar 22, 2017 3:27 PM.


#4 save2600 OFFLINE  

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Posted Wed Mar 22, 2017 3:08 PM

n/m



#5 eightbit OFFLINE  

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Posted Wed Mar 22, 2017 3:23 PM

It must have been some force to break the pin right off. I could see bending it, but a clean break? I have never encountered floppy pins that are so brittle as to snap on ANY of my Amigas.

#6 Nebulon OFFLINE  

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Posted Wed Mar 22, 2017 3:29 PM

It must have been some force to break the pin right off. I could see bending it, but a clean break? I have never encountered floppy pins that are so brittle as to snap on ANY of my Amigas.

I'm hoping that you're right.

 

It does seem a bit strange for the second pin in from the end to break and not the last one as well.

 

I'll do more research into this and see if I can pull up more motherboard revision photos.



#7 eightbit OFFLINE  

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Posted Wed Mar 22, 2017 3:31 PM

I wonder if it was broken in the past and then patched. I wonder if a previous owner purposely broke it in order to use a blocked pin floppy cable like this one:

https://i.stack.imgur.com/tdcDr.jpg

Edited by eightbit, Wed Mar 22, 2017 3:32 PM.


#8 Nebulon OFFLINE  

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Posted Wed Mar 22, 2017 3:50 PM

I wonder if it was broken in the past and then patched. I wonder if a previous owner purposely broke it in order to use a blocked pin floppy cable like this one:

https://i.stack.imgur.com/tdcDr.jpg

Hmmm.... This pieces are beginning to fall into place here.

 

Pun sort of intended.



#9 JamesD OFFLINE  

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Posted Wed Mar 22, 2017 5:34 PM

Maybe other people don't remember the "missing pin scandal" series of posts from back in the day, but there was this guy that stirred up a fuss because the drive connector had a missing pin... aaaaaand it was for the keyed connector.  Not sure what forum that was on.  Amiga.org?
 



#10 JamesD OFFLINE  

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Posted Wed Mar 22, 2017 5:41 PM

Compare to this picture

http://www.bigbookof...2000rev43mb.jpg



#11 eightbit OFFLINE  

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Posted Wed Mar 22, 2017 10:59 PM

That's a busted off pin....or so it looks to me. Might have been missing on that rev board...not sure. I have a rev 6.3 and all pins are there.

 

To the original poster: Does the floppy drive still WORK?


Edited by eightbit, Wed Mar 22, 2017 11:01 PM.


#12 JamesD OFFLINE  

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Posted Wed Mar 22, 2017 11:15 PM

That's a busted off pin....or so it looks to me. Might have been missing on that rev board...not sure. I have a rev 6.3 and all pins are there.

 

To the original poster: Does the floppy drive still WORK?

 

No, it's a keyed connector. 
 



#13 eightbit OFFLINE  

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Posted Thu Mar 23, 2017 10:12 AM

So many people spoke of keyed connectors on Amiga's but I have never owned one with one. Then again, I have only owned A500's and A2000's (and once an A600) in my lifetime.



#14 Nebulon OFFLINE  

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Posted Thu Mar 23, 2017 10:19 AM

The floppy drive works in the other Amiga (the one with all the pins intact). Interestingly, both the A2000 with the missing pin / internal drive issues and the working Amiga 2000 are both Rev 6.2 boards.

 

I also have a PC floppy drive cable kicking around here (new actually). And it has a piece of plastic. But instead of being the second hole in from the red wire, it's the third hole from the red wire that's plugged with plastic.

 

And to confuse things even more, I found a picture on the web of a floppy drive cable that has the second hole in from the red wire blocked and on the other end of the cable, the third hole in from the red wire is blocked with plastic.

 

?!?

 

So now I'm wondering what on earth is happening in MFM disk drive world. If I go through my really old cables and disk drives, no pins are missing and no connector holes are blocked. It's too bad manufacturers couldn't have just stuck with that since it doesn't hurt anything to plug a data cable in backwards.

 

Does anyone have the pin-out for the motherboard's floppy drive connector? I'm wondering what the second and third pins in from the red wire actually do...



#15 Nebulon OFFLINE  

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Posted Thu Mar 23, 2017 10:33 AM

This article suggests the Amiga has a slightly different pinout than a PC for the motherboard disk drive interface. Two things that stood out when I read it were:

 

http://pinouts.ru/HD...sk_pinout.shtml

 

"The same thing affects the classic Amiga. It uses a very slightly modified Shugart interface pinout at the motherboard (the other /MTRON on pin 4) and a PC drive just doesnt work correctly unless the /DCD is remapped to its original pin. The correctly mapped /DCD is enough for AmigaOS but many trackloaders (X-Copy Pro for example) require the /RDY signal which the drive should set low when the motor rotation has stabilised. This signal does exist on most drives but at worst it requires relocating a soldered SMD jumper on the circuit board."

 

and

 

"On some mainboards pin 3 is used as the key (missing pin) and on some pin 5 is used as the key pin, while a lot of mainboards dont have the key pin removed at all. This can all cause problems when using cables which have the key pin hole closed. As all odd pins are ground there are no technical implications in modifying such cables by removing the key pin closure by force."

 

So pin 3 matches up with the PC cable that I got recently.

 

That still leaves the Amiga's missing pin 2 as a bit of a mystery (unless maybe pin 2 on the Amiga serves the purpose of pin 3 on the PC?)

 

To be continued...



#16 Nebulon OFFLINE  

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Posted Thu Mar 23, 2017 10:39 AM

Okay, so now that I've seen a diagram and not just a list of pin numbers, I can see that pin 3 would be two in from the end, since they're numbered in a zig-zag pattern.

 

The diagram and description suggest that both pin 3 and 5 (or two in and three in from the end) are unused and are just connected to ground).

 

And that bodes well for JamesD's statement that it's keyed.

 

That would be good!  I can't wait to work on this machine on the weekend.

 

http://www.primroseb...torage_fdis.htm


Edited by Nebulon, Thu Mar 23, 2017 10:46 AM.


#17 JamesD OFFLINE  

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Posted Thu Mar 23, 2017 11:43 AM

LOL, the "missing pin scandal" thread was caused by Commodore not communicating the change to dealers.
The first boards weren't keyed, so when this guy got one that was, he brought it to the dealer and was like WTF?

And the dealer was like, WTF?  I've never seen that before.
And they opened a couple other new machines and were like WTF?  It must be a bad run of machines!
PANIC!  SCANDAL!  BEWARE!  RED ALERT!   ALL ENGINES STOP!  Defective machines!

Someone returned sanity to the thread and was like... it's keyed!
Oh... really? 
Yeah really.
Are you sure?
I'm sure.
Never mind.

The thread erupted with "mine is missing a pin too" or "mine's not like that" replies for a couple days.
We actually had people call us about it. We were an authorized dealer/service center.
When we heard about it we laughed.
 



#18 eightbit OFFLINE  

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Posted Thu Mar 23, 2017 10:12 PM

Yes, and I stand corrected as well! I had my A2000 apart today to finally replace that stupid loud PSU fan with a nice quiet Noctua 80MM fan (which was a success!) and double checked the floppy connector while I was there. Indeed it is keyed on my Rev 6.3 model (missing the pin), and indeed the floppy cable itself had the pin stuck in the hole :) So, you did not break anything. This is how it is....at least on certain models. My old eyes thought this one was full pin the last I checked, but I guess not. Interesting nonetheless :)


Edited by eightbit, Thu Mar 23, 2017 10:15 PM.


#19 Nebulon OFFLINE  

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Posted Fri Mar 24, 2017 10:51 AM

Yayy!  Thanks everyone. I wasn't as awful to my Amiga 2000s as I thought I was.

 

Regardless, that one machine is giving me the one-two Kung-Fu kick.

 

Everything from it alternating between the Workbench 1.3 insert disk screen and trying to load WB from diskette (it does that strange alternating thing about 100 times a minute sometimes).

 

Then there's the weird GURU on reset that happens about once every three reboots.

 

Ack!



#20 eightbit OFFLINE  

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Posted Fri Mar 24, 2017 3:29 PM

I had issues with a previous A2000 I acquired as well. It would guru every bootup and do all sorts of strange things. I found the CPU socket was poorly patched and when I tried to fix it it only got worse. There were other patches and things on the board as well and I threw in the towel on it, purchased another A2000 (which is pristine) and kept the leftovers from the first one as spare parts.

The biggest problem with the A2000 (other than the exploding battery) is that it was a big box computer that was MEANT to be opened for upgrades and so on. Because of this you had a lot of inexperienced people inside of these machines messing about. Pretty difficult to get an unadulterated model in general because of this.

Alternating between WB and disk does not seem normal though...never saw that before.

#21 JamesD OFFLINE  

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Posted Fri Mar 24, 2017 10:50 PM

I had a 3000 motherboard that would go for days without a problem and then boom... corrupt hard drive.
I tried swapping several chips but nothing worked.  It was impossible to track it down to another component due to the intermittent nature of the problem so I finally had to swap motherboards.


Edited by JamesD, Fri Mar 24, 2017 10:51 PM.


#22 Nebulon OFFLINE  

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Posted Tue Mar 28, 2017 12:47 PM

I had a 3000 motherboard that would go for days without a problem and then boom... corrupt hard drive.
I tried swapping several chips but nothing worked.  It was impossible to track it down to another component due to the intermittent nature of the problem so I finally had to swap motherboards.

Many years ago, I corrupted an Amiga 2000 SCSI chain because I didn't terminate it properly.

 

The other thing I ran into was that some devices had trouble with certain drive controllers. I ended up ordering a Guru ROM upgrade for the SCSI controller I was using (I think it was so that I could use a 1GB Jaz drive).



#23 JamesD OFFLINE  

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Posted Tue Mar 28, 2017 9:21 PM

Many years ago, I corrupted an Amiga 2000 SCSI chain because I didn't terminate it properly.

 

The other thing I ran into was that some devices had trouble with certain drive controllers. I ended up ordering a Guru ROM upgrade for the SCSI controller I was using (I think it was so that I could use a 1GB Jaz drive).

The 3000 has the SCSI controller on the motherboard.  Swapping boards made the problem go away.
I seem to remember a hard drive controller we sold needing an upgrade.  GVP?



#24 Zippy Zapp OFFLINE  

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Posted Tue Mar 28, 2017 10:34 PM

Heh. I did the same thing to my A2000.  Pulled the cable out and there was a pin in the Ribbon connector that was not there previously.  But like yours my turned out to be a ground pin and it wasn't necessary so it worked anyway.  I remember asking the same question on another board and got the same response with "It's a key pin it's supposed to be missing".  haha It could be true but is it supposed to be on the header one minute and in the ribbon cable another?   ;-)



#25 Nebulon OFFLINE  

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Posted Thu Mar 30, 2017 12:17 PM

The 3000 has the SCSI controller on the motherboard.  Swapping boards made the problem go away.
I seem to remember a hard drive controller we sold needing an upgrade.  GVP?

 

Yep! You are correct. It's GVP.







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