[Coco] calling all MM/1 owners

[Bob Devries]

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.

--
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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