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From: nevets@ihlpm.ATT.COM (Steven R Ringwood)
Newsgroups: comp.sys.amiga
Subject: Re: PALs,jumpers and expansion on the Amiga 1000.
Message-ID: <1367@ihlpm.ATT.COM>
Date: Fri, 4-Sep-87 09:52:18 EDT
Article-I.D.: ihlpm.1367
Posted: Fri Sep  4 09:52:18 1987
Date-Received: Sat, 5-Sep-87 18:04:08 EDT
References: <8709010613.AA05631@cogsci.berkeley.edu>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 66
Keywords: Two on the Bus
Summary: It works -- for me at least

In article <8709010613.AA05631@cogsci.berkeley.edu>, bryce@COGSCI.BERKELEY.EDU (Bryce Nesbitt) writes:
> The solution that has worked in several cases is to improve the grounds for
> these PALs.  The ground pins of each of the four PALs are connected, and a
> clip extends from the last PAL (U6J) down to the motherboard.  Here's a
> diagram:
> 
>      ^ clip
>      |
>      |    J	   K	  L      N
>      ---X---O  X---O  X---O  X---O
>	  O---O  O---O  O---O  O---O
> 	  ..........................
> 
> The X's indicate pins to be connected.  The clip connects to ground on the
> motherboard at a point just to the left of the power supply connector
> (There is a row of 8 capacitors with ground on the side nearer the
> connector).
> 
> |\ /|  . Ack! (NAK, EOT, SOH)
> {O o} . 
> ( " )	bryce@hoser.berkeley.EDU -or- ucbvax!hoser!bryce
>   U	If "hoser" does not work, try my old address at "cogsci"


Bryce sent us this other solution to the bus problem just when I had
discovered my Amiga would not work with two devices on the bus.

So I decided to try it, opened up the Amiga, took of the shield,
and sat and thought about how to do the job.
In the end I used wire-wrap wire, a solding iron, and an old alligator clip.
Since the pins in question were flat against the board, i first straightened
them out.  (I used a dentist tool to lift the pins away from the board).
Then using a single piece of wire and careful spot stripping, i
connected the four pins together.  The wire was wrapped around a pin,
the a small (very small) drop of solder applied, then on to the
next pin.  For practical reasons i started at U6J and left extra wire hanging
toward where the clip would be attached and worked toward U6L.

I then attached the alligator clip, and clipped it to the negative end
of one of the capacitors.  A note of caution here, not all the
capacitors have the negative side toward the connector.
The negative side can been told by the large blue strip and large minus sign.

Bryce also mention a capacitor on the diving board, i skipped this
step.

Did it work, for me YES.

Before making this change i could not get by 2Meg Starboard II and
Supra 30Meg harddisk to work together.

After the 'fix', they both work but only if the Supra is first on the
bus for some reason.

It took me about two hours from start to finish working at a slow pace.
Since the job requires solding i would not recommend it to everyone,
but if you are confortable with this type of work it is not very
difficult.

Thanks to Bryce for this tip.

BTW: How many people knew that besides the paw print, and many
	English signatures, two of the signatures are in Chinese?
	
Steven Ringwood
ihnp4!ihlpm!nevets