Graphics problem on Amiga 2000

[Jupp3]

Hi!

I've got quite "basic" Amiga 2000, it's got 1MB CHIP, 8MB Fast, SCSI controller and a SCSI-HD, and that's it.

But the problem is, suddenly some rather strange problem appeared... I guess something is corrupting the CHIP memory, which can be seen as graphical corruption (and grabbed with screengrabber)

An example can be seen here.

It also seems to affect other things related to chip memory (when playing sid, for example, after a while some sounds will become corrupted and stay so... But when playing mods from FAST memory with Hippoplayer, all is fine)

So... Anyone got any idea, what could be the problem and the solution for it? :-)

I once took most (easily) removable custom chips from A500 and installed those into my A2000, but the problem seemed to stay...

I've also tried removing expansion cards, but that didn't seem to help either...

I'm not that interested in upgrading my A2000 in any way (except maybe a bigger HD) as I already have 2 far more powerful computers (my 060/PPC A1200 and G4 Pegasos 2), but wouldn't mind having it in fully working condition :-)

EDIT: The link should work now...

[AMIGA-FAN]

Your link:

http://www.ratol.fi/~jujokela/WBGrab2.gif"]here[/url].

doesn't seem to work, I get a response saying that I can't access it as I do not have permissions to access that file.
Is it spelt correctly?

Regards.

[Computolio]

    Bad RAM?

[mikey2001]

I had this problem too on my A2000, and I think it was because the graphics level was set too high for the ECS chipset to handle properly. Im not 100% sure if this is the cause, but I still have this problem today, but only on a sporadic basis. :-(

[TheMagicM]

I thought bad ram also but since you've pulled all the boards out... Have you thought about booting into a plain WB to see if you could recreate the problem? (maybe a program is causing that?)

[Tomas]

this is just a plain guess, but have you checked the PSU?? I heard of other people getting sound/gfx problems when using a flacky psu, so it might be worth checking.

[BoingBoss]

Hi Jupp3,

It sounds like one or more of the DRAMs on the motherboard are bad.  Since these DRAMs are soldered to the motherboard I know that you did not "swap" these.  With the cover off and the Amiga 2000 running touch the top of each DRAM with your finger one chip at a time.  Make sure that you place your whole finger on top of each DRAM and hold it there for a few seconds.  If a chip feels hot then that is the one that needs to be replaced.  44256 DRAMs are very hard to find, but I do sell them from time to time.  Let me know if you need any.   :-)

[kd7ota]

I remember getting screen graphics corruptions similiar, but they werent as bad. It would only be when text was displayed, and certain text would be corrupted.

I fixed the problem by replacing the FAST ram that was on my A1200 accelerator with 32mb one, and then everything worked perefect and the mysterious crashes left... So you may want to try to switch memories first.. :-)

[Azryl]

okies, sounds silly, but also pull your Kickstart ROM out of its socket and reseat it....  sometimes the kickstart can have intermittant contacts on one or more of its pins, pass all start up tests but get flakey results like random crashes, garbage on screen and display/sound corruption.

Although you also have sound issues, I would also suggest running a memory checker thru your chip ram, a faulty chip there can really play havock with the Amiga.

best of luck fault finding

[EdKing]

Azryl wrote:
okies, sounds silly, but also pull your Kickstart ROM out of its socket and reseat it....  

I am having the same type of problem on my 2500, I think it is either O.S 3.1, or maybe the ROM, as I don't seem to have this problem when I boot from O.S. 2.04

Ed King

[Robbie]

yeah just try a memory check program. I know one came with Wordworth. I'm sure there any many others too

[motrucker]

  This could easily be bad RAM, But it could also be several other chips gone or going bad. Can you get your hands on a Advanced Amiga Analyzer? This is a set of software routines with a set of cables that will tell of many Amiga problems. It has a good memory tester, and a video port tester.
 (IF you want one, I will sell one for $25.00 (almost new))

[Argus]

Check the motherboard revision.  If it's a Rev. 4 board then someone probably did the 1MB hack to convert the 512K slow-FastRAM to ChipRAM.  There's a jumper or connection pad at the rear of the machine that you have to cut or bridge (or both) to do this.  You can find the hack details on the net (Aminet).  Perhaps the solder or cut is breaking away or incomplete.  I'd look into this because it would give the machine errors trying to access that second 512K as ChipRAM and affect graphics.  Rev 3 mb's also need a hack to fit a 2.04 or 3.1 ROM if I recall so check to see if you have the right wires and pins lined up there (should be a small wire from rom socket pin 1 to rom socket pin 31 and a second wire from rom pin 21 to bent-up rom pin 31...or something like that).  Also, make sure the Agnus chip (C=8372) is seated in its socket fully and inspect the RGB port connection to the motherboard (there could be a flaky connection there if it has been plugged in a million times).  If you could lay hands on a flickerfixer or Opalvision video slot board you could bypass the standard RGB port entirely and see if this clears the problem.

[Jupp3]

Meant to post a reply here earlier, but forgot...

Have you thought about booting into a plain WB to see if you could recreate the problem?

I think the problem occured also at the "Insert disk" -screen when booting without any expansion cards...

Can't recall the motherboard revision, but it's one of those, that have onboard B&W composite out.

And yes, there was some self made "memory expansion" when I got it, some wires connected to the base of some chip. But when I got it, I just removed them (previous owner said, that disabling it was required to use 3rd floppy drive) and in any case, it worked just fine for maybe an year after that...

[Argus]

@Jupp3

Sounds like you have a B2000 motherboard (the American/modern design) then if you have the b/w composite out.  If it's a Rev 4 m/b or higher #, there should be no extra wires on the ROM IC.  Rev 4 boards also need the m/b hack and the Fat Agnus (8372A/B) to address the full 1MB of soldered RAM as ChipRAM.  Make sure the hack was done correctly.  I never heard of a third floppy hack (or why you'd need one with two internal and an external port).  Hopefully, the previous owner didn't fry something.  I'll do some more checking, there may be a way to adjust the RGB video port on the m/b (maybe it's slightly out of wack).