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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: BGary335 on September 13, 2007, 12:26:06 AM
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I seem to be having some trouble with my A500, and I'm hoping someone can help. I jsut received an GVP A500-HD+ today, and after getting it all connected and ready to go I powered both it and the 500 up. The HD boots into WB 2.x (not sure precisely what version it is, but thank god I was able to get my 2.04 ROM working), and everything seems fine. I then put a floppy in the drive, at which point it came up on the WB screen as DFO????? (it is a PC disk, so that's normal). A second or two later the screen goes completley green, and the power LED starts blinking. I shut the system and HD off, and then boot both back up again, and got a green screen, instead of the usual greys. so I turn it off, turn it back on again, and get a black screen. I then reseat each of the chips on the board one at a time (except the Agnus) one at a time, but still nothing but a black screen. I hope reseating the Agnus solves the problem, but if it doesn't, does anyone know what could possibly be the problem?
Any help would be appreciated!
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Well, I reseated the Agnus, and still nothing but a black screen. However, I noticed that after 30 seconds or so, the green floppy light comes on as though a disk is being read, despite the fact that there is no disk present in the drive.
Again, any help would be greatly appreciated!
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Try booting A500 when GVP unit is detached...see if that changes something back to normal self-test colors...
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Nothing changes. I get nothing but a black screen and then the floppy light comes on about 30 second later.
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Sorry to say, but you might start considering your FatAgnus passed away at worst...do you have PLCC extractor for FatAgnus reseat procedure ?
I don't recommend even thinking to pull-out that chip without tools designed for that job.
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I don't have the exact tool needed, but I was able to improvise. I can pull the chip out in a flash. In fact, I tried that to see if it fixed the problem, but it did not.
So, if it IS the Agnus, where on earth am I going to find a replacement?
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Unless someone here has one they want to dump, I would suggest emailing Software Hut (softhut.com) and ask. They'll probably let it go fairly cheap if they have one.
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I believe a green screen is caused by a problem with the RAM. Do you have a trapdoor RAM expansion? Try unplugging it and booting the A500. Some have a rechargable battery inside that will leak over time and damage the board.
The only chips I have ever had go bad in an Amiga are the CIA chips, so I doubt that your agnus has failed (but I have been wrong before).
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I've read that the green screen indicates bad Agnus, but that a black screen indicates no CPU. so since the CPU is there, I probably should look for a new Agnus.
As for the RAM expansion, I already checked that. I pulled it out and put it back in, but it made no difference.
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Hunt for a new working Agnus as a result of a half-educated guess may be a bad idea.
I would advise getting cheap A500 or even motherboard alone...
For example:
http://cgi.ebay.de/AMIGA-500-Motherboard-Kickstart-1-3-Rev6A-100-ok_W0QQitemZ200152035258
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narmi wrote:
but I have been wring before
Sorry to be pedantic, but that really is priceless! :-D
- Ali
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Lockon_15 wrote:
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I don't recommend even thinking to pull-out that chip without tools designed for that job.
Not to "pull" it out, but to "push" it out from below the board.
I remember I once did it that way, before I bought me an chip puller.
But you have to dismount the motherboard for that.
There is a hole in the board - just below the Agnus chip (at least on the revs I had)...
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The only chips I have ever had go bad in an Amiga are the CIA chips, so I doubt that your agnus has failed (but I have been wring before).
More probably a bad contact, but of course a bad chip is also possible. I have a spare 500 that used to need a push every now and then on the Agnus to get rid of the green screen. There was a buch of bad sockets giving trouble, cracking easily. Check the socket pins, if there is visible oxidation.
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I got in touch with Software Hut this morning and they have an Agnus chip that they're going to sell me for $5 total (inc. shipping). So for such a low price I'm willing to take a chance. If the Agnus turns out to not be the problem, I've only wasted $5. And really, that money isn't wasted because I can always hang on to the Agnus in case I ever do need it.
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InTheSand wrote:
narmi wrote:
but I have been wrong before
Sorry to be pedantic, but that really is priceless! :-D
- Ali
Nice catch! It's fixed now (so stop laughing at me :-D ).
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Alright, so I got a new Agnus chip, but that doesn't seem to have cleared anything up. I boot up the system, and get a black screen, and after about 30 seconds or so both the internal and external floppy lights come on and stay on. Anyone know anything else that could be the cause of this problem?
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Try a new psu, unhook everything including the floppy drive and check for battery leaking. Battery corrosion can cause all kinds strange symptoms.
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I've checked the battery, but I don't see any signs of leakage. So I guess we can cross that out. I don't have another PSU, so I can't try that.
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Hi,
please take the time to clean each chip and support with an electronic contact cleaner spray and a teethbrush.
It highly seems to me that you got an oxydation problem like I had :rtfm:
if you can get an OLD PC AT psu or an ATX, use the floppy connector to power it (but plug also CDROM, HDD... on the psu to make it load well).