[Coco] calling all MM/1 owners

[Joel Ewy]

Bob Devries wrote:

> Joel, as far as I know, the termination resistors have a power and a

> ground pin at opposite ends with a number of pairs of 220 and 330 ohm

> resistors strung between them. The centre point of these pairs is

> connected to the SCSI bus data/control lines. Yes, having them

> backwards would make some difference, but how much? Certainly it

> appears that it's not enough to stop the SCSI cold.

>

Sounds like you need to do some rework on your I/O board.  :-(  I'd
offer to send you some parts but it probably doesn't make sense to ship
to Australia from central Kansas.  (There ought to be some kind of
tornado-powered Oz to Oz express wormhole...)  I still have MM/1 I/O
board parts, though I have it in the back of my mind that the
terminators for the SCSI interface may have changed to a different
package between the board you have and the ones I was going to produce. 
And I have a rail of unused DS1287As -- brand new in about 1994.

JCE

> -- 

> Regards, Bob Devries, Dalby, Queensland, Australia

>

> Isaiah 50:4 The sovereign Lord has given me

> the capacity to be his spokesman,

> so that I know how to help the weary.

>

> website: http://www.home.gil.com.au/~bdevasl

> my blog: http://bdevries.invigorated.org/

>

> ----- Original Message ----- From: "Joel Ewy" <jcewy at swbell.net>

> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>

> Sent: Friday, January 25, 2008 1:54 PM

> Subject: Re: [Coco] calling all MM/1 owners

>

>

>> Bob Devries wrote:

>>> I just removed the I/O board from the MM/1 to more closely examine the

>>> RTC.

>>>

>>> I found that one of the termination resistors for the SCSI bus is

>>> oriented the opposite way to the other two. RN5, the middle one is

>>> different. Now I'm wondering what effect this will have on the working

>>> of the SCSI bus? Could this be my problem?

>>>

>>> Joel, the termination resistor's 'notch' or 'dot' end should be in the

>>> solder pad that's square, am I correct?

>>>

>> Yeah, that's right.  I think that's the common lead for the resistors.

>> Resistors themselves aren't directional.  Does it make a difference

>> because of the way they're assembled in an array?

>>

>> JCE

>>> -- 

>>> Regards, Bob Devries, Dalby, Queensland, Australia

>>>

>>> Isaiah 50:4 The sovereign Lord has given me

>>> the capacity to be his spokesman,

>>> so that I know how to help the weary.

>>>

>>> website: http://www.home.gil.com.au/~bdevasl

>>> my blog: http://bdevries.invigorated.org/

>>>

>>> ----- Original Message ----- From: "Dave R in Illinois"

>>> <lazyhand at sbcglobal.net>

>>> To: <coco at maltedmedia.com>

>>> Sent: Thursday, January 24, 2008 12:03 PM

>>> Subject: [Coco] calling all MM/1 owners

>>>

>>>

>>>> Have you checked to make sure the drive / cable is properly

>>>> terminated? I've

>>>> seen corroded pins on terminators do strange things to raid arrays. I

>>>> never

>>>> owned a mm1 so I am not sure if there even is one, I would assume

>>>> there

>>>> would be.

>>>>

>>>>

>>>>

>>>> -Dave

>>>>

>>>>

>>>>

>>>> ______________________________________________________

>>>>

>>>>

>>>>

>>>> I have a small problem with my MM/1, and I'm wondering if there was

>>>> ever a

>>>> fix for it?

>>>>

>>>> When I power it up, the computer goes through its procedure to try to

>>>> boot

>>>> from the floppy, and then from the SCSI hard disc. It *always* locks

>>>> up the

>>>> SCSI bus at that point, and pressing reset does not unlock it. I

>>>> need to

>>>> cycle the power to unlock it. It then usually fires up correctly, but

>>>> not

>>>> always.

>>>>

>>>> My MM/1 is a 3MB with the expansion board. It has a 170MB Quantum SCSI

>>>> drive. The drive itself initialises properly (at least, it makes

>>>> all the

>>>> right noises).

>>>>

>>>> Comments anyone?

>>>> -- 

>>>> Regards, Bob Devries, Dalby, Queensland, Australia

>>>>

>>>> Isaiah 50:4 The sovereign Lord has given me

>>>> the capacity to be his spokesman,

>>>> so that I know how to help the weary.

>>>>

>>>>

>>>> -- 

>>>> Coco mailing list

>>>> Coco at maltedmedia.com

>>>> http://five.pairlist.net/mailman/listinfo/coco

>>>

>>>

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>>>

>>

>>

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