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%% COMMODORE A3000 Video Speckle Defect By Julie Peterson %%
%% (LadyHawk@cup.portal.com) %%
We have discovered a pattern, for at least 4 people and want to
know if there are more. If so send me email and I'll consolidate
information. Here are the symptons:
- Horizontal speckles appearing on the display, worse in
programs that have a lot of screen refreshes or
moving objects or text. Most people initially suspect
a monitor problem, but it's NOT a monitor problem.
- Problem is gradually progressive over a period of weeks
or months, depending on how often you use the computer and
in my case, may have caused the eventual shutdown of my system.
- Programs which save what's on the video display are
a particular problem, as they will save the glitches
also (e.g. DPaint images will save what you draw *and*
the intruding glitches).
- ghosting, double images in flashes, and worse along
the edges and scrollbars are typical as problem worsens.
- the actual RUNNING of programs is not affected. You
can boot workbench and applications just fine, the
'workings' are not effected, just the video output and
in some cases, screen saves with garbage added.
I will have more empirical information soon, but one person
reported swapping all chips without locating problem, some people
have done partial swaps without discovering source, or solving the
problems. I am looking for patterns and help for all concerned.
If you have these symptoms, please email:
Full description of symptoms
Age, model, and serial number of the machine
Stock machine? Or add-ons?
Length of problem
Steps you have taken to try to solve it
If you have it, is it progressive in your case?
And ESPECIALLY, if you got it solved, let us know. One of the
things we need to find out is if this is a factory defect in a
particular production run, and of course, we want to know how to
fix it. Thanks! I'll consolidate stories and post.
Responses from users:
1. My display began doing strange things in early november. Primarily just
flashing and occasional bits of garbage (none lasted more than an instant).
About a week later the problem became worse and bits of garbage began showing
up and staying. These bits became progressively, over the month of november,
worse and worse until heavy garbage and frequent screen flashing showed up.
2. Not sure if this is the same problem as I have it on an A2500.
Yes. Particularly bad in text displays or windows that fill the whole
screen. On the workbench sometimes a pull down menu will leave a garbled
ghost behind. Or an icon will turn to garbage --but still work.
> - ghosting, double imames in flashes, and worse along
> the edges and scrollbars are typical
> - the actual RUNNING of programs is not affected. You
> can boot workbench and applications just fine, the
> 'workings' are not effected,
Also: IT GOES AWAY! It is not happening now for instance. Making a text
window smaller than the screen diminishes it when it is happening.
It has come and gone for a year or so. It's been more frequently recently.
Seems to last 3 or 4 days.
I tried checking that chips were socketed firmly, particularly Agnus. When I
have the chance (and tools) I want try swapping or reseateing Agnus.
3. roblems: On leaving the computer on for more than 2-3 hours (on a cool
day) I get weird things happening. (Happens in less than 30mins on a warm
day) Mostly static on my screen (concetrated on/around scroll bars). Terminus
prints weird characters. When I ran a BBS, the computer would crash on
uploads (not sure if same problem, worth mentioning), while the exact same
BBS software would work fine on friends 3000.
Attempts to fix: Tried removing commodities, things in Startup-Sequence...
Placed the computer on wooden blocks... Screaming at the computer repeatedly..
[Julie's Note: thought this sounds only partly like other descriptions, it's
worth noting that some people had disk AND video problems with similar
symptoms, but which were NOT related to the CIA chips 8520s.]
4. The glitches I notice are a horizonal dash, usually 8 pixels wide.
They would 'fly' around the screen, sometimes sticking. And you
could then capture the display with the glitches.
The glitches could also show up on a screen not currently to front.
Made for an ugly surprise when returning to WB screen. :(
Problem suddenly showed up mid Oct '93. Owned since July '91.
At first, I thought it may have been some new software I may have
installed, but symptoms happened under a stock WB.
The flying glitches also showed up during heavy program activity,
that appeared not to be related to screen rendering, like during
a page print from Pagestream. But this process may have been using
CHIP ram for its purpose.
Sorry, can't tell you if they are in color or not, as I use a 2024
These glitches occurred under all screen modes.
- ghosting, double images in flashes, and worse along
the edges and scrollbars are typical
These symptoms occurred a few weeks later, and that is when I found
that the entire 2nd bank of CHIP ram had gone bad. Bad bits and a bad
address line (#15). NEC brand. Replaced the chips, edges cleared up,
but speckles remain.
Programs worked OK, no unexplained GURUs.
All memory and system checkers that I could find indicated the machine
was in perfect shape.
(note: If a 3000 has bad CHIP ram, memory checkers will fail to find
it. The chips must be removed and tested in a chip checker, or
installed in a 2091 and tested with the software that comes with
This is how I found out I had a meg of bad CHIP ram.)
Swapped Agnus, CIAs, Paula, and Denise, to no avail.
Did not swap out Ramsey, Gary, DMAC, CPU or FPU.
I was finally able to make it happen all the time.
The glitches occurred when the available CHIP ram was less than 1 meg
free (system using the 2nd bank of CHIP ram).
This was my solution, to return the machine to 1 meg CHIP ram. :(
But, no more glitches!
I did not pull the soldered bank of CHIP ram, as the glitches are
gone when using just this bank of ram. Still could be bad though.
My unconfirmed suspicions is that the problem is in the 'Bridge' ram
system where the CPU can access the CHIP ram.
Machine is about 2.5 years old, running nearly 24 hours a day, using
appropriate surge suppressors on ps and phone line.
A3000 desktop Rev 7.0 mb, factory upgraded to 7.3, rev 6.1 daughter bd
All original chip revs
Gary -02; Ramsey -04; Buster -06; SDMAC -02; Proto WD SCSI chip
SuperKS 2.04, WB 2.1
2 meg CHIP, 4 megs FAST (1x4 SC ZIP)
8. I am writing in response to your report of "speckles" on your A3000. I
have experienced the same thing as well....usually flashing green dots that
only appear on some programs screens. Doesn't happen to often, but on
programs that have a gray background this usually happens. (Not WB
surprisingly though). By local Amiga repairman made a guess that it was
badly installed ROM chips. You might want to try that....I don't really
[Julie's Note: This sounds similar, but not quite the same as the
problem reported by others. The horizontal blip or speckle tends
to show up on most screens and is not color-related. Whether it
is a few dots or a lot depends more on the number of screen
activity and refreshes than on color combinations, but I included
this message just in case they're related.)
9. I had and fixed an obscure problem with my A3000 this year which may
or may not be similar to that you described in your posting. The problem
I had was primarily with the display and floppy drives.
I started getting short random length horizontal lines, from one pixel
to less than 1/8 inch, appearing on the display. Moving/resizing
windows might add more "garbage". Resetting the workbench would clean
up the display until new activity added more "garbage".
I also would have windows in the back flash on the front screen during
[Julie's Note: This is a perfect description of the video problem.]
I was also having problems with my floppy drives -- read and write
[Julie's Note: If you are using a hard drive and only read from
floppies, you may not realize you have disk problems too (I didn't
at first). Floppy disk problems show up most often on writes and
formats. If you are having the speckle problem, check your floppy
I attempted to have my system repaired at a dealer, but was
[Julie's Note: Several other people reported their dealers not
able to locate this problem. Agnus, Denise and CIA are most often
checked, but often without results.]
So it was left to me to fix my A3000. I observed that the problems
manifested themselves after the system had warmed-up so it was likely
a heat sensitive component. I also figured the problem was related to
CHIP memory so I narrowed my troubleshooting to the CHIP memory
subsystem. The memory test program I tried didn't show any
problems, though I think it did lock once or twice.
I purchased a can of "COMPONENT COOLER" at Radio Shack, opened up my
A3000, and waited for the problems to appear...
The problem turned out to be a heat sensitive PAL chip, U202, in the CHIP
MEMORY sub-system. The P/N is 390526-02.
The solution required me to purchase blank 16L8D PAL chips and make a
copy of the original. CBM doesn't sell replacements, except as part
of a motherboard swap.
My system is like new now; except for a dead key on my keyboard. (It
was the RETURN key until I moved it.) I have since added a 240 MB
hard drive and an external CDROM drive.
My configuration at the time of the problem:
A3000/25-50, internal 880k floppy, 2MB CHIP, 8MB FAST
S/N 0001024, Motherboard "B2" P/N 313313 Rev 9/03
Date of purchase 10/06/91
A1011 external 880k floppy
Firecracker display board
I hope my ramblings have added to your knowledge base....
[Yes, thank you very much to ALL who responded. Hope this
information can help, and if there's more, email me and I'll post
further installments. Especially send solutions, and you might
want to print this and take it to your repair person if you have
problems you can't fix yourself.]
10. I'm running an older A3000 and my Screen Speckle problem started
just recently. I started having problems with the display going black
a few minutes after power on. Eventually I narrowed the problem down
to a flaky fat agnus.
When I first replaced the fat agnus, the vertical lines were wavy,
I tweeked an adjustment to the rear of the fat agnus and the wavy lines
It was just after replacing and tweeking that the speckling showed up.
I've only seen it once or twice but have not had my machine up more than
a few times since replacing the fat agnus.
btw, the part I installed was an 8372B. There is some confusion in my mind
about the correct part number. Some advertisments lead one to believe that
you can use an 8275 chip.
[Julie's Note: I'm not sure if this is the same problem or not,
it sounds like one problem (the screen speckle problem does not
cause the display to blank out) followed perhaps by a different one,
which may or may not be the speckle problem. As a general note,
there is a little nob on the back of the A3000 and a tiny plastic
'screw driver' that came with your operating system disks, when
you get the A3000. In the A3000 manual (the little one) it
explains how to adjust this pot to adjust the video. This may
help some people's problems, but will not remedy the 'screen
speckle' problem we're trying to remedy, but try it.]
11. Well I just read your post about A3000 video problems, I never
had the 'speckle' problem, but sometimes when I would drag an icon it
would 'smear' or leave ghost images. First I thought it was a problem with
one of the chips (the Agnus) but I took it into a store and they replaced it
even though the tech could not duplicate my problem when he was fixing it at
the store. Well he told me it could be a heat problem, and it IS a heat
problem. If you A3000 gets too hot then it starts messing up the gfx, but
everything else runs fine. Lucky for me I like to keep my apartment cold, so
I don't have that problem anymore. I only experienced this problem during the
summer when my room would got very hot. I do not know of a 'real' solution
besides keeping the area cool, maybe removing some of the plates in the back
to get more air circulation, I dunno ..
[Julie's Note: Different from speckle problem, but thought I'd
include it for those with heat problems.]
Email if you have the problem and if you've solved it, especially!
COMMODORE A3000 Screen Speckle Defect - Chapter 2
First, clarification. People have emailed me with what is turning out to
be a variety of similar (but not the same) video problems. This is fine,
I'm posting most of them. This kind of information is still valuable, even
if we're chasing more than one problem here. But I wanted to clarify, the
problem I'm describing here specifically (and the fix that seems to be
working) is a short 'blilp' that looks like a dash or hyphen. It extends
only a few pixels horizontally (usually about 8 or so) and is only 1 or
maybe two pixels high. It's like someone dropped an alphabet soup bag
with only hyphens onto your screen, settling randomly and sometimes
appearing to 'stick' there (specially in DPaint if you try to draw something)
Second, GREAT NEWS. We're starting to get news back from people who are
finding the solution. The posts I got from people who had found the
problem and fixed it themselves (I have yet to get a single letter from
someone who found a dealer able to diagnose this problem) point to a
PAL chip and to Chip RAM. So check these out. The PAL chip is part
number 16L8DCN (and it's inexpensive - yay!). A GAL can be used, as
long as it's programmed for the PAL (16V8GAL). Both these chips are
10 nanoseconds. One person found the problem in the second socketed
bank of Chip RAM, the other found it in the first, soldered bank of RAM
(bad news), but check out the PAL chip first, maybe you'll be lucky.
I'm happy to say, one of the folks on IRC got his computer back in order
($2.50) after being 3 months without it. That made my day.
COMMODORE A3000 Screen Speckle Defect - Chip Available
OK! If your problem is genuinely the screen hyphen speckle problem, and
not a different problem (or combination of problems), it appears as if
HT Electronics can help. I just ordered the GAL (Gate Array Logic chip,
I think) from them and they went to some trouble and experimentation to
program it for the PAL parameters. They are happy to supply the solution
to those who need it, but they want to be sure users understand that this
is only a fix for this specific problem. If ou have another problem and
order the chip, you can't hold them responsible if this doesn't fix it!
So be fair to them; they're good guys.
HT Electronics Sunnyvale, CA 1-408-737-0900 16V8GAL programmed to
function like 16L8DCN PAL
I was so thrilled, I didn't even ask what it was going to cost. I know
the chip is cheap, but they had to find a programming solution and there's
shipping too, so it's going to be a bit more, but better than a non-
functional computer! Ask for Sales, if you call HT.
Classic - Concepts (LadyHawke@cup.portal.com) wrote:
: COMMODORE A3000 Screen Speckle Defect - Chapter 2
[- stuff deleted -]
: Second, GREAT NEWS. We're starting to get news back from people who are
: finding the solution. The posts I got from people who had found the
: problem and fixed it themselves (I have yet to get a single letter from
: someone who found a dealer able to diagnose this problem) point to a
: PAL chip and to Chip RAM. So check these out. The PAL chip is part
: number 16L8DCN (and it's inexpensive - yay!). A GAL can be used, as
: long as it's programmed for the PAL (16V8GAL). Both these chips are
: 10 nanoseconds. One person found the problem in the second socketed
: bank of Chip RAM, the other found it in the first, soldered bank of RAM
: (bad news), but check out the PAL chip first, maybe you'll be lucky.
: I'm happy to say, one of the folks on IRC got his computer back in order
: ($2.50) after being 3 months without it. That made my day.
: Julie (LadyHawke@cup.portal.com)
Question? Is this PAL that fails the same component? In my case it
was U202. If so, it could be either a bad batch of PALs used to make
this component or that this device is being operated outside the
recommended operating conditions leading to pre-mature failures.
My U202 was a MMI PAL 16L8DCN 011G2KM.
Inquiring mind wants to know...
Hats off to Julie for this thread and for the solution. We were at our wits e
with this problem; we swapped chips, cooled ram, removed chip ram
all to no avail. HT provided the GAL, and presto! solved the problem.
Julie has saved the State of California (and all U.S. taxpayers) the
cost of a serious repair. The U.C. system thanks you.
A3000 Screen Speckle Defect - Installment 4
I have more news about the screen defect problem and some
First, in answer to your question, yes the socket location is
U202 (PAL). It is located in the forward left quadrant of the
A3000 at the forward left point of the large square chip (U205)
as you stand in front of it (not under the drives, thank goodness).
I confirmed that my U202 chip was bad by opening a friend's
A3000, removing his U202 and installing mine. The EXACT same
speckle defect (horizontal blips about 1 pixel high and 2 - 8
pixels wide, especially bad near the edges of windows, and the
bits tend to 'stick') appeared on his machine.
I then took out the defective U202 and installed the original
chip. Everything was fine. I then replaced the original chip
with the chip sent/programmed by HT Electronics. It worked
Then I got brave. DON'T TRY THIS. You could fry not only the
chip, but the motherboard as well (I've been doing hobby level
chip swapping long enough to have fairly good instincts about this
and haven't fried anything yet, but I don't recommend this seat of
the pants approach to others.) One of the people who got an HT
chip reported a gray screen and no fix. I was really worried
about this, thinking that either he got a bad chip from HT, or I
had guessed the problem incorrectly, so I decided to take the
risk to find out. I deliberately installed the good chip in
backwards. You will get a solid lightish gray screen that remains
and displays nothing further. I removed it, tried it the right
way [meanwhile writing out my will, since this is my friend's
pride and joy], and [unfortunately, for my heirs] it works fine.
It was worth the risk. We now know what happens if you get
it in wrong. Shut off your machine IMMEDIATELY and rotate the
chip. If your problem is not then solved, you either have a
combination of problems, or your screen speckle is different from
the one I've tried my best to describe here.
One observation. How do you know which way to install the
chip? Normally, the little indentation on one end indicates the
end that matches the number on the circuit board. The indentation
should be towards the *back* for this chip ... but, I discovered
in all of this, that's not 100% true. In my A3000, there was one
of each, but both LABELS faced the same way (turn your face left
to read them. In Craig's machine, there was one of each (indents
faced two ways before I removed anything), but again, the LABELS
on the chips listing the part number both faced so you could read
them by turning your head to the left. I can only guess this is
sloppiness, different production runs, or that the label, not the
notch, is the indicator (though it shouldn't be that way). The
HT chip was correctly oriented.
Oh, about cost. By the time you pay for the chip, the
research HT did to figure out the programming, the downloading of
the programming, and the shipping, you're looking at about $28.
Since an hour in a shop trying to guess the problem often runs $35
- $60, this is a pretty substantial savings.
Finally, get the information out so we can help others! You
are welcome to reprint these posts in user group newsletters (so
we can help people frustrated with this problem who might not have
access to Usenet), just remember to tell them to get a qualified
person to do it if they have no hardware experience, that it may
void their warranty, AND that it's at their own risk. :-)
Julie Petersen (LadyHawke@cup.portal.com)