Green Screen With A500

source · 16 October 2009, 02:41

I have just purchased an A500 it arrived today, and when I plugged it in, I was confronted with a flashing power led. the display was green. I took the computer apart, and removed all the socketted chips and reseated them including the agnus. still no improvement. I removed agnus and replaced with one i already had still same green screen. Is this indicating the memory on the motherboard is toast. could a green screen represent any other condition with the computer. It only has 512 kb and 1.3. Bare bones. Any help would be greatly appreciated.

source · 16 October 2009, 02:43

Does anyone know where to seen boards for repair near Ontario?

8bitbubsy · 16 October 2009, 02:52

Partly on-topic:
You should also check for bad solder joints or leaking capacitors... As well as "broken components", like smashed resistors etc. The green screen does indeed indicate an error with the RAM, but it doesn't have to mean that the RAM is borked. Can be a lot of things, really...

Just spend a long hour scanning the mobo with your eyes (like lasers in future movies!! whoa) !!
Another good idea is to strip the parts, and see when it eventually will boot.. However, in a stock a500 there's not much to strip

source · 16 October 2009, 03:24

This machine when I openned it was imaculate. The clear plastic cover over the name plate is still in place. No dust inside the machine. I looked for leaking capacitors, but could not see any on the glance. Does anyone know of a repair place?

Zetr0 · 16 October 2009, 06:30

@source,

sounds like a chip ram failure,

take any chip upgrade out and inspect the memory chips, pending on revision this maybe 8 or more,

turn on you Amiga and *carefully* place the back of your finger on each of the chips, the if you find a HOT one, thats the puppy thats died.

you will need to replace this, fear not, you can find these chips on plenty of 1/2 meg upgrade cards

What revision of A500 you got?

Paul_s · 16 October 2009, 10:47

try removing ram expansions too. I remember when I got a 500 again it was doing the same - removed duff card and booted fine.

source · 16 October 2009, 13:24

The board is revision 6. There are no addons in the A500 it is the bare bones unit.

rkauer · 16 October 2009, 21:35

Do what my very good friend Zetr0 said: with the cover open, fire up the Amiga and then put your finger over the memory chips (those 8 chips on the far "south" of the board). If one is hot to touch, replace it.

If no avail, the other possible culprit is the Agnus socket: those things are made by cheap polyester (nylon) plastic and it becomes fragile as glass as the years pass.

Wrong time to be poetic, I know.

prowler · 16 October 2009, 21:48

Quote:

Originally Posted by rkauer

...those things are made by cheap polyester (nylon) plastic and it becomes fragile

Hi rkauer,

If that material is polyester, then is isn't nylon. Nylon is polyamide and it doesn't become fragile.

rkauer · 16 October 2009, 23:01

Polyester is a kind of synthetic nylon, as polyethylene terephthalate (PET, used in beverage bottles). In industry it is called PA 6.6 (hard nylon). But you are also right, polyamide is made slightly different.

Due the add-on charges utilized (pure plastic is expensive) on the sockets they become brittle as years passes.

Shadowfire · 17 October 2009, 19:55

During bootup, the Amiga will check chip ram starting at location $00000000 and work its way up, until it finds the end of continuous RAM. Basically, it writes/reads data. When it "finds" the end of memory (via a mismatch read/write), it checks to make sure there is at least 256K - if not, it throws the green screen ("chip ram error").

What this really means, is that there has been a RAM access error. Because the OS was able to execute the diagnostic and write the green-screen code, you can safely rule OUT the 68000 or Kickstart ROM as a source of the problem. However, the RAM error itself can actually be from any number of things: bad/dead RAM IC, maybe the RAM decoupling capacitors have been damaged or are dead, traces severed on the board, agnus IC dead or dying, agnus socket issue etc.

The upshot is, you probably aren't going to be able to fix this without either expensive lab equipment and expertise, or replacing components "shotgun" and hoping to find the one that is the problem.

The "hot chip" method discussed earlier in the thread will find IC's with internal shorts, but none of the other potential problems - still, it is worth it to perform the test, since it doesn't take long to do.

source · 27 October 2009, 05:20

I have found someone who does repairs here in canada, and the mobo is on its way.

rkauer · 27 October 2009, 05:50

IIRC, a shot Gary chip can issue a green screen, too.

16 October 2009, 02:41	#1
source Zone Friend Join Date: Jul 2005 Location: Toronto, Canada Posts: 734	Green Screen With A500 I have just purchased an A500 it arrived today, and when I plugged it in, I was confronted with a flashing power led. the display was green. I took the computer apart, and removed all the socketted chips and reseated them including the agnus. still no improvement. I removed agnus and replaced with one i already had still same green screen. Is this indicating the memory on the motherboard is toast. could a green screen represent any other condition with the computer. It only has 512 kb and 1.3. Bare bones. Any help would be greatly appreciated.

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16 October 2009, 02:43	#2
source Zone Friend Join Date: Jul 2005 Location: Toronto, Canada Posts: 734	Does anyone know where to seen boards for repair near Ontario?

16 October 2009, 02:52	#3
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,715	Partly on-topic: You should also check for bad solder joints or leaking capacitors... As well as "broken components", like smashed resistors etc. The green screen does indeed indicate an error with the RAM, but it doesn't have to mean that the RAM is borked. Can be a lot of things, really... Just spend a long hour scanning the mobo with your eyes (like lasers in future movies!! whoa) !! Another good idea is to strip the parts, and see when it eventually will boot.. However, in a stock a500 there's not much to strip

16 October 2009, 03:24	#4
source Zone Friend Join Date: Jul 2005 Location: Toronto, Canada Posts: 734	This machine when I openned it was imaculate. The clear plastic cover over the name plate is still in place. No dust inside the machine. I looked for leaking capacitors, but could not see any on the glance. Does anyone know of a repair place?

16 October 2009, 06:30	#5
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@source, sounds like a chip ram failure, take any chip upgrade out and inspect the memory chips, pending on revision this maybe 8 or more, turn on you Amiga and carefully place the back of your finger on each of the chips, the if you find a HOT one, thats the puppy thats died. you will need to replace this, fear not, you can find these chips on plenty of 1/2 meg upgrade cards What revision of A500 you got?

16 October 2009, 10:47	#6
Paul_s Registered User Join Date: Nov 2006 Location: Amigaville Age: 46 Posts: 3,337	try removing ram expansions too. I remember when I got a 500 again it was doing the same - removed duff card and booted fine.

16 October 2009, 13:24	#7
source Zone Friend Join Date: Jul 2005 Location: Toronto, Canada Posts: 734	The board is revision 6. There are no addons in the A500 it is the bare bones unit.

16 October 2009, 21:35	#8
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	Do what my very good friend Zetr0 said: with the cover open, fire up the Amiga and then put your finger over the memory chips (those 8 chips on the far "south" of the board). If one is hot to touch, replace it. If no avail, the other possible culprit is the Agnus socket: those things are made by cheap polyester (nylon) plastic and it becomes fragile as glass as the years pass. Wrong time to be poetic, I know.

16 October 2009, 23:01	#10
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	Polyester is a kind of synthetic nylon, as polyethylene terephthalate (PET, used in beverage bottles). In industry it is called PA 6.6 (hard nylon). But you are also right, polyamide is made slightly different. Due the add-on charges utilized (pure plastic is expensive) on the sockets they become brittle as years passes.

17 October 2009, 19:55	#11
Shadowfire Registered User Join Date: Aug 2001 Location: Connecticut USA Posts: 617	During bootup, the Amiga will check chip ram starting at location $00000000 and work its way up, until it finds the end of continuous RAM. Basically, it writes/reads data. When it "finds" the end of memory (via a mismatch read/write), it checks to make sure there is at least 256K - if not, it throws the green screen ("chip ram error"). What this really means, is that there has been a RAM access error. Because the OS was able to execute the diagnostic and write the green-screen code, you can safely rule OUT the 68000 or Kickstart ROM as a source of the problem. However, the RAM error itself can actually be from any number of things: bad/dead RAM IC, maybe the RAM decoupling capacitors have been damaged or are dead, traces severed on the board, agnus IC dead or dying, agnus socket issue etc. The upshot is, you probably aren't going to be able to fix this without either expensive lab equipment and expertise, or replacing components "shotgun" and hoping to find the one that is the problem. The "hot chip" method discussed earlier in the thread will find IC's with internal shorts, but none of the other potential problems - still, it is worth it to perform the test, since it doesn't take long to do.

27 October 2009, 05:20	#12
source Zone Friend Join Date: Jul 2005 Location: Toronto, Canada Posts: 734	I have found someone who does repairs here in canada, and the mobo is on its way.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

27 October 2009, 05:50	#13
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	IIRC, a shot Gary chip can issue a green screen, too.