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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: mrtabaka on January 18, 2007, 08:38:53 AM
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Hi,
I have still problems with A3000T. Paths are repaired, but now when I boot A3000T I have green screen or red screen. I put off Zip rams (only 1mb soldered CHIP is on motherboard), I put for a moment FAT Agnus from A500 (8372A) and nothing change. The situation is the same on Philips 8833 II and on VGA monitor. I don't have any card puted into Zorro etc.
What to do:((((
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The fat agnus from the a500 is only a one meg chip. Wouldn't work even if you pulled the zip ram, and would result (I imagine) in a green screen.
Red screen is a bad ROM. Pull and check the roms for bent pins, replace ROMs and the zips and original 2 meg agnus. See what happens after that.
I'm having the green screen problem with my A3000T also. Waiting for a replacement agnus.
Good luck, the A3000T is an awesome unit.
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T3000 wrote:
The fat agnus from the a500 is only a one meg chip. Wouldn't work even if you pulled the zip ram, and would result (I imagine) in a green screen.
Hey T3000, are they not pin-compatible? I believe I had a 8273B work in an A500 rev. 6a, although I don't remember it so well, so perhaps I'm only dreaming.
I also see the poster of this thread confirm that a 8372A works in his A3000:
http://www.amiga.org/forums/showthread.php?t=30076
Could you verify if it would work? Thanks
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Doesn't a red screen at power-up indicate a problem with the Kickstart ROM?
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Yes.
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da9000 wrote:
... I believe I had a 8273B work in an A500 rev. 6a, although I don't remember it so well, so perhaps I'm only dreaming.
hmm... I looked and looked, but could not find anything on the 8273B. Must be some kinda super secret "military spec" chip. Either that, or you transposed some digits... :-D
da9000 wrote:
I also see the poster of this thread confirm that a 8372A works in his A3000:
http://www.amiga.org/forums/showthread.php?t=30076
Could you verify if it would work? Thanks
Looks like from the other topic, that the 8372A one meg chip may function in the A3000. I'm not gonna start chip swapping to find out though...
Soooo many variables...
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There are different flavors of Agnuses - and you can't (for sure) tell by the stamped number...
Usually an 8372A is from A500/2000, 8372B/8375 from A500+/600 and 8372AB from A3000 - they are not pin compatible (http://de.wikipedia.org/wiki/Agnus_%28Amiga%29#Pinbelegung_PLCC-Versionen).
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murple wrote:
Doesn't a red screen at power-up indicate a problem with the Kickstart ROM?
It can also be caused by faults on the address bus, such as a broken trace between CPU and ROM, or 2 address lines shorted together etc
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T3000 wrote:
hmm... I looked and looked, but could not find anything on the 8273B. Must be some kinda super secret "military spec" chip. Either that, or you transposed some digits... :-D
LOL :-)
Yeah, I looked very hard as well and couldn't find anything, except your post and the one in the link.
T3000 wrote:
Looks like from the other topic, that the 8372A one meg chip may function in the A3000. I'm not gonna start chip swapping to find out though...
Soooo many variables...
Yeah, so he says in that link... but I'm not so sure as I haven't asked him (yet) to verify this for me, and also the statement isn't so clear.
I also asked the resident Agnus-gnostic master himself, AlexH and he says emphatically: NO
@ALL:
What Doobrey says about the possibility of a red screen caused by something other than a faulty KS is right, and the same goes for pretty much all the other colors: they aren't *necessarily* caused by an actual *chip* itself failing, but also possibly from a faulty connection/wiring to said chip(s), or a combination of faulty chips and wirings (as in my sad A3000 case...).
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I dropped an 8375B 318069-03 into my Rev 9/03 board equipped A3000, no problems. Originally socketed with 8372AB 3189069-03.
8375B 390544-XX is obviously not for the A3000 but I believe the key thing to remember for A3000s is the part #'s on the 8375 chips, it will tell you which ones you can and cannot use.
The wiki info posted above needs to be updated and is missing vital info and doesn't take into account part #'s. More accurate info is here (http://www.jochi.de/speichertabelle.html)
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Green and red screen booting A3000T
If you don't find it A3000, you should at least find it A3000T.
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@57goldtop:
Can you verify if a 8372A worked in your A3000? (as mentioned in your thread: http://www.amiga.org/forums/showthread.php?t=30076)
As for the part #s, yeah, it makes sense.
I saw the http://www.jochi.de/speichertabelle.html site from the recent newgroup threads, but I'll wait for AlexH's all-encompassing (and Englishized) Agnus Encyclopaedia! :-)
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da9000 @ I ran my A3000UX with one for around 6 months before I was able to get my hands on the right chip, having said that I can't confirm if that is true for all A3000 rev boards but it was for both my Rev 9/03 & Rev 9/02 machines.. I don't intend on spreading mis-information but I simply report what I have observed.
Some of the earlier A500+ machines actually used the 8375 318069-XX 2Mb Agnuses as found in the A3000T. However the majority of A500+s used the 390544-xx variant.
Commodore did a lot of strange things.