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From: grr@cbmvax.UUCP (George Robbins)
Newsgroups: comp.sys.amiga
Subject: Re: Amiga 1000 - PAL Pin 10 Grounding Gripe
Message-ID: <2703@cbmvax.UUCP>
Date: Sun, 8-Nov-87 04:43:20 EST
Article-I.D.: cbmvax.2703
Posted: Sun Nov  8 04:43:20 1987
Date-Received: Tue, 10-Nov-87 07:31:43 EST
References: <2153@gryphon.CTS.COM>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Organization: Commodore Technology, West Chester, PA
Lines: 40

In article <2153@gryphon.CTS.COM> bilbo@pnet02.cts.com (Bill Daggett) writes:
> Ever since I expanded my A1000 2 months or so ago with a 2Meg Micron board and
> 20Meg Supra hard drive I've experienced various gurus/crashes that have been
> attributed partly if not completely to the PAL (timing?) chips.  I replaced
> the "so called" affected PALs causing expansion port trouble with the
> faster/better variety prior to using the expansion port but this seems not to
> be enough.  Through Supra I learned that ALL the PALs have floating pin 10s
> that should be grounded.  And I asked them to send me info on this operation
> along with a new Supra driver program disk - all of which I am still waiting
> for 3 weeks later.
>  
> And I thank you in advance very much.  My gripe is that if Commodore knows
> that these pin 10s are not grounded and that the health and well being of my
> computer has probably been suffering for it WHY can't they make it "official"
> in some way with details on how the user can get their machines fixed - either
> take it to a dealer or "do-it-yourself"?  Or have my eyes and ears been closed
> up tight?  GRIN...  I hope that Commodore can discover a way of communicating
> with Amiga users better -- please bear in mind and respect that I am not a
> hacker/programmer type but an end user.

The problem, sir, is that Pin 10 on the PAL's are grounded.  If you (or others)
will check, the two PAL's that are lifted from the mainboard (U6K and U6N)
obtain power and ground thru the headers that connect them to the mainboard,
while the other two are part of the daughter board power and ground system.
To the innocent, this may not make much sense, but there are a number of
reasons for wanting to control the number of points where you want grounding
systems interconnected.  When used with devices that follow the precepts
mentioned in the expansion documentation and good engineering practice it
seems to work pretty well, while others, especially those combined in non-
buffered stacks or daisy chains seem to have problems.

If you want to try the reputed "fix", which may well help in some cases, simply
solder a very short wire between pin 10 of U6J and U6K and one between pin 10
of U6L and U6N.  Oh yeah, voids the warranty, but that's most likely academic
at this point.

-- 
George Robbins - now working for,	uucp: {ihnp4|rutgers|allegra}!cbmvax!grr
but no way officially representing	arpa: out to lunch...
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)