From: mrubino@csws12.ic.sunysb.edu (Michael N Rubino)
Subject: Re: A3000 struck by lightning, which chips to replace?
Organization: State University of New York at Stony Brook
Date: Mon, 17 Aug 1992 00:01:51 GMT

In article <15767@star.cs.vu.nl> sreiz@cs.vu.nl (Reiz Steven) writes:
>My A3000, actually my modem, has been struck by lightning.
>At first, it seemed a simple case of 'dump blasted modem, 
>buy new one', but after I had done that, it turned out that
>it wasn't just the modem that smelled of burned toast...

I know EXACTLY how you feel.  My A3000 was hit on Tuesday :-(  I believe a
surge came through the phone line.  My modem was toast as well as the 3000's
power supply, 8520's, 1488 and 1489 (more on those later).

>My amiga still works, but it is acting very weird... I'm trying
>to figure out which chips should be replaced. The first thing I
>noticed was that when trying to move icons, the old image would
>stay behind, and after a few more mouseclicks the machine would
>hang. Besides that, the serial port wouldn't work, not even with
>the new modem. I seemed to recall that the icon problem could be
>caused by bad CIAs, so I swapped both with the two in my A500.
>And indeed, the icon problem was fixed (well, transfered to the
>A500)!

I had a similar problem.  My floppy was also going nuts.  New 8520's did the
trick.

>Unfortunately, the serial port still doesn't work,

Look at the 1488 and 1489 chips.  I believe they are at loactions U304 and
U305.  They are located at the rear right of the mother board, right next to
the serial port.  Actually, you can look at the schematic in the "Introducing
the Amiga 3000" book, page E-7.  Page E-1 shows the whole MB but you'll never
find the 1488 and 1489.  It's probably one or the other but I replaced both.
The only thing is that they are soldered to the MB.  I now have the chips in
sockets (just in case).

> and I've found some more problems:
>- Sometimes a green screen at bootup (means 'bad chip ram').
>- Reading/writing floppies is very unreliable.
>- Sound samples are played with a lot of noise and distortions.

Sounds like Paula.  She takes care of sound and floppy access as well as the
serial port.  Mine seems to have survived.

>- The screen is distorted by small horizontal lines that 'pop up'
>  regularly, they have different colors, are mostly 8 pixels wide,
>  sometimes 16, occasionally only 1 or 2 pixels wide, and after they
>  pop up, they are there to stay (i.e. they don't disappear, unless
>  I clear the window/screen, and in shell windows they scroll up with
>  the text when I press return.)

Hmm... could be Agnus or Denise.  Try Paula, 1488 and 1489 first and see how
things are.

>I think that this points to a chip ram refresh problem. Could this also
>cause the serial port to disfunction?  Which chip does chip ram refresh
>in an A3000? (Ramsey? Agnus?) I'm only assuming here that the problem is
>limited to chip ram. Could other defects cause these symptoms? Are
>there any specific tests I can do to track down the problem?

I work at an Amiga dealer so I ran the CBM test software on my machine.  It
passed all tests but I can't seem to get my new modem (Supra V.32bis) to do
data compression.  I'll have to play some more.

I'm going to look into filing a claim with my home owners insurance.  Hopefully
they'll cover some of this.

I'm also going to get a surge surpressor for the phone line.  From now on I'll
unplug the phone line AND power during an electrical storm.

>I would VERY much appreciate your help on this one, TIA!
>
>	Steven

Good Luck!!
-- 

- Mike
  mrubino%csws1.ic.sunysb.edu@sunysb.edu <--- use this address for email.
  
Newsgroups: comp.sys.amiga.hardware