Path: utzoo!utgpu!watmath!att!pacbell!ames!henry.jpl.nasa.gov!elroy.jpl.nasa.gov!gryphon!jdm
From: jdm@gryphon.COM (John Mesiavech)
Newsgroups: comp.sys.amiga
Subject: Re: MotherBoard(Rev 6) Noise Problem with HardFrame
Message-ID: <18629@gryphon.COM>
Date: 9 Aug 89 10:37:00 GMT
References: <268@syteke.UUCP> <21093@cup.portal.com>
Reply-To: jdm@gryphon.COM (John Mesiavech)
Organization: Trailing Edge Technology, Redondo Beach, CA
Lines: 75

In article <21093@cup.portal.com> DavidS@cup.portal.com (David Kenneth Schreiber) writes:
>in article 268@syteke.UUCP, Jim Sanches writes:
>
>>I just purchased a 2000 with a Rev 6 motherboard in Germany and picked
>>up a MicroBotics Hardframe while I was in the US.  The hardframe came
>>with Rev 1.55 software.  I found that when I tried to format or prep
>>the drive(a Quantum-40S by the way) that is was VERY intermittent.  It
>>would hang the system requiring a power off or work partially.  When
>>I finallly got it preped(after serveral attempts) I found that the
>>same behavior would occur during a copy df0: dh0: all.  I finally
>>called MicroBotics in Texas and Mike(their QA/QC) guy tells me that
>>yes Commodore KNOWS about a noise problem on the motherboard and is
>>getting a fix out for it "real soon now".  Has this news come out on


The fix is simple.  Turns out there's a chip at position U605 that can generate
an excessive amount of noise on the bus, causing random Gurus with
some highspeed peripherals that demand a clean bus.  The fix is
known to CBM dealers, and involves a 100K resistor to be soldered
onto two legs of the chip.  If you have a Rev 4.4 motherboard, the
rev changes to 4.5.  If you have a 6.0 motherboard, it changes
the rev to 6.01.

 [stuph removed for brevity]
>
>I recently bought a 2000 from Go Amigo that was also rev. 6.  I also
>installed a Hardframe and an 8-UP DIP memory board with 2 megs (I have
>a 67 meg Epson SCSI hard drive attached to the Hardframe).  When I used
>either one of the boards by themselves, they worked fine.  Together, I'd
>be lucky to go two minutes before guruing.  I took the machine in to a
>local dealer to be looked at;  the dealer called Microbotics and got
>basically the same story you did.  He called Commodore and was told
>in essence "what problem?"  So I called Go Amigo and they exchanged my
>2000 for a rev. 4.5 machine in which they installed the one-meg Fat

[diatribe removed for brevity]

>at                                              DavidS@cup.portal.com
>

Davit et al;
 
The local dealers here in Cal have known of problems with the rev 6
motherboard for some time (since they started getting them).  The
Rev 6 motherboards have significant noise problems with the bus slots,
and any timing-sensitive peripheral won't work reliably on them.  These
types of devices include DMA peripherals, and ram expansions.
 
If your board rev is 4.5, you don't have the problem.
 
At first, the dealers thought it was the Fat Agnus chip that caused the 
problem, but experience has since proven that it's not.
 
BTW David, in me personal machine I'm running a Hardframe-2000 connected
to TWO Quantum drives (a Pro-40 and a Q280), with a 8-up SIMM board
populated to 4 megs, a tablet card (Easyl), AND a A2620 board.
 
I can definitely say that there are no Guru problems with the above
mentioned setup.  
 
You may have gotten a defectinve board somewhere.
 
John


-- 

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|                   ----------------------|-------------------             |
| "I want a New Duck                      |  John Mesiavech                |
|  One that won't try to bite             |  net.soldier.of.fortune        |
|  One that won't chew a hole in my socks | {backbone}!gryphon!jdm         |
|  One that won't Quack all night"        |    Go Purdue! (by req)         |
|  Weird Al Yankovic, "I Want a New Duck" |                                |
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