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Newsgroups: bit.listserv.i-amiga
Date:         Thu, 3 Sep 1992 12:21:09 +1000
From:         "David Johnson,
              CSIRO Div. Wool Tech." <DJOHNSON@GEEL.DWT.CSIRO.AU>
Subject:      RE: Purple screen????
X-To:         I-AMIGA%RUTVM1.BITNET@pucc.Princeton.EDU

On Wed, 2 Sep 1992 16:48:04, Alejandro J. Kurczyn S.
<AKURCZYN%ITESMVF1.BITNET@pucc.Princeton.EDU> writes:

> >Date: Wed, 19 Aug 1992 10:07:34 +0100
> >From: Blaz Zupan <uel111r2a%tferi4@uni-lj.ac.mail.yu>
> >To: I-AMIGA@rutvm1.bitnet
> >X-VMSmail-To: UEK::MX%"I-AMIGA@rutvm1.bitnet"
> >X-VMSmail-CC: UEL111R2A
> >Message-ID: <0095F52F.A6E23B80.24304@uni-lj.ac.mail.yu>
> >Subject: RE: Purple screen????
> >
> >> OK, this is starting to get REALLY old!  First my A500 starts giving me
> >> a black screen on cold boots, and only would reset if given a three finger
> >> salute, then it wouldn't work without a drop test...
> >> (I know, but it worked for a while... ) now I have had a really strange
> >> thing... I got a ?PURPLE? screen
>
> I think it has to do with the Denise, Agnus or CHIP ram chips, I had a similar
> trouble with my A500 rev 5 machine, I changed the Agnus to the 1MB and a
 faulty
> Agnus was installed (a missing pin!) on the machine, the result was a purple
> screen, reinstalling the old agnus didn't solve the problems. The only
 solution
> we found was to change the motherboard (to a rev 6) along with the agnus.

Purple is indeed a self test error code, but I can't remember which. If
nobody posts what it means soon, I'll try to look it up.

> About the black screen, I also had a similar problem when I burned out my
> Denise, it worked fine for some minutes then *poof*, all was black. Sometimes
> a cold boot would work and some times not. Try replacing the Denise. By the
> way, I burned it because I have a "screen filter glass", you know, the ones
> supoused to ease eye strain and "radioactive emissions" from the monitor, my
> "filter" has a ground wire and I didn't used it. Maybe a spark or something
> jumping from the filter to the monitor screen burned the Denise.

I'd be VERY surprised if a spark from your filter could cook a Denise. It
would have to be one hell of a ZAP! C= 1084 monitors are notorious for
bad connections causing a loss of picture. This would be the first place
I'd look. My monitor was REGULARLY losing picture (sometimes accompanied by
an electrical splat). Sometimes a whack on the side of the case would make
it work for a while. I pulled it apart, and there was a BAD solder joint
on the bottom of the tripler. I resoldered it and have not had a problem
since. I've also heard of problems with the locating tab on one of the RF
shields shorting out and causing similar problems. I think the 1080
monitors are much the same inside.

The other place picture LOSS could occur is in one of the CIAs. One of
them has a hand in the video output.

The purple could be indicating a power-on-self-test failure in one of the
CIAs. Try swapping them and seeing if it changes the colour you get. Is
anything else not working properly? The CIAs are involved in the Parallel
Port, the Mouse Ports, the Video Output and probably a few other places as
well. Swapping them should fix one fault, and give you a different one
somewhere else.

> By the way, do you know of any "glitches" in the memory using the 1MB Agnus
> activated? Sometimes I get #0003 guru numbers and the screen gets trashed
> once in a while (when short of memory).

I've not seen this.

all the best

dave   +----------------------+------------------------------------------------+
+------+                      |  CSIRO Division of Wool Technology             |
| David Johnson               |  PO Box 21, Belmont, Australia, 3216           |
| djohnson@geel.dwt.csiro.au  |  +61 52 472-651 (voice)   +61 52 472-657 (fax) |
+-----------------------------+------------------------------------------------+
     Most men are within a finger's breadth of being mad.        - Diogenes
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