name resolution

[Liam Proven]

On 26 November 2017 at 09:41, Gene Heskett <gheskett at shentel.net> wrote:
>>
> And after you'd fixed that again , it was still the termination.

Ex-ACT-ly!

> 99% of
> all the termination problems with scsi is that the designers of the
> interface cards specced a schotkey diode for the powerline isolation
> diode, but the fscking bean counters changed it for a std si diode on
> the way to the production floor because it was $3 cheaper, with its .7
> volts voltage drop across it, which in turn reduced the logic one noise
> margin to zip, so the bus errors were at least once per write. One
> company that makes cards for the amiga even drew up the artwork for
> resistive terms bass ackwards, so in addition to putting a schotkey
> diode in it, I had to cut the traces and reverse the 5 volt and grounded
> ends of all 3 of its soldered in terminators. That card never again had
> a bus error that wasn't a fading psu. The termination was finally fixed.
> Logic one resting voltage was finally at 3.3 volts, the design target
> for a scsi bus. But watch for fading psu's, long before the logic or
> anything else complained because the 5 volts was down to 4.7, screwing
> the logic one noise margin, the buss errors were raising their heads
> again.

That's... terrifying.

I am, sadly, almost totally incompetent at electronics. Stuff like
this was well over my head.

I've certainly seen machine/drive combinations that Just Would Not
Work, though, when both tested fine with other devices -- and now you
make me wonder if it was electronics/component-level problems.

> But that was the 2nd time in my life as a journeyman C.E.T., which I  am,
> that I called the maker and gave him hell, telling him the best part
> must have run down his mothers leg. Totally unrelated but important in a
> production room for a tv station where we had quite a few amiga's doing
> video work, and several of the A4000's had 68060 cards in them, I found
> that some production people at Commode Door had installed all the 6.3
> volt electrolytic bypass caps backwards on that $1500 card.

:-o

> Took about a
> year before they started blowing out the tops. With the soldering tools
> of the day, fixing that wasn't my idea of fun. But by then there wasn't
> anybody answering the phone at Commode Door.

:-(

The early Amigas were a premium product, but had to compete in a
mass-commodity market.

> Just before I retired in 2002 as the CE there at that tv station, we
> bought some Apple G5's to replace the failing amiga's, but they should
> have come with fire extinguishers. None of them lasted 6 months.

Wow!

That's horrific.

Time did show that the G5s *were* pushing the PowerPC envelope, but
still, they were _beautifully_ built machines. I still have one, over
a decade old and working fine.


> Which, if dealing with a sata thats flooding the syslog with bus and
> drive resets, and the sata cables are that pretty hot red color, replace
> them with ANY other color of cable, that plastic dye converts the copper
> its in contact with into powdered copper oxide. Very poor conductor.

:-o

> That plastic dye was known to be a problem by the early 1970's as cable
> production moved to the J.A.Pan company, but all the cable makers could
> see was a booming business selling replacement cables as it was always
> the red wire that failed. See it, replace it with any other color.

... Wow.

-- 
Liam Proven • Profile: https://about.me/liamproven
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