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Offline DanAdamKOFTopic starter

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A500: Green Screen/11 blinks, reseating chips didn't help...
« on: March 17, 2012, 09:26:01 PM »
I recently bought an NTSC Amiga 500 with a version 6 motherboard, that won't boot up.  It shows a green screen on the TV, and the Power light blinks 10 times short, 1 time long, then repeats.  The caps lock light can be toggled 11 or 12 times then stops being toggleable.

Except for the Denise and CPU, I pulled every chip carefully with chip pullers, cleaned the chip legs and socket, and reseated them, and I went over the Denise and CPU legs with a generous amount of alcohol as well, but there was no change.  I let the A500 run for about an hour, the Fat Agnus was warm but not hot, and the RAM chips were cool.

I also visually inspected the board and saw no cold joints, scraped traces, burned-out components, or bad capacitors.  The previous owner was the original owner and only opened it once just out of curiosity, but never did anything on the inside.

I've been doing all this without any trapdoor RAM installed by the way.

It looks like I've done all there is to do when the A500 is acting like this.  But if any of you guys have suggestions about other things to try, I'm all ears.
 

Offline skywalkgr

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #1 on: March 17, 2012, 09:42:10 PM »
agnus is properly seated?
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Offline DanAdamKOFTopic starter

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #2 on: March 17, 2012, 09:43:45 PM »
Quote from: skywalkgr;684205
agnus is properly seated?
It seems like it.  I pulled it with a PLCC puller and put it back securely twice.  I could try it over and over I guess?
 

Offline spirantho

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #3 on: March 17, 2012, 10:09:23 PM »
Almost certainly a bad Chip RAM IC. It'll be difficult to diagnose without removing each of the RAM chips I'm afraid!
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Offline lost_loven

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #4 on: March 17, 2012, 10:10:50 PM »
green is chip ram error. . have you looked here?
http://wiki.classicamiga.com/Amiga_boot_error_code_colours
lost
A3000D 2 meg chip, 4 meg fast,128 meg zorram! 16 gig scsi2sd, 3.1 ROM, A3640, Indivision ECS, X-surf-100. Rapid Road usb, Amd scsi chip, Buster11. FTP service now with my Ethernet WD2TB Live Book, haha love it !
hp lappy.

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Offline DanAdamKOFTopic starter

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #5 on: March 17, 2012, 10:14:05 PM »
Quote from: lost_loven;684209
green is chip ram error. . have you looked here?
http://wiki.classicamiga.com/Amiga_boot_error_code_colours
lost
I did run across a similar page saying that the green screen is either a chip RAM issue or an issue with something on its bus.  As far as I could tell, people were saying to test chip ram by feeling it and if it's too hot to touch, it's bad.  Is there another way to test RAM, such as with a multimeter?  Will bad RAM show certain points being abnormally shorted/open internally or anything like that?
 

Offline lost_loven

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #6 on: March 17, 2012, 10:20:10 PM »
here is another link with a similar problem.. just reading it now.. might have some insight for you..
http://www.amiga.org/forums/showthread.php?t=20817
lost
« Last Edit: March 17, 2012, 10:33:42 PM by lost_loven »
A3000D 2 meg chip, 4 meg fast,128 meg zorram! 16 gig scsi2sd, 3.1 ROM, A3640, Indivision ECS, X-surf-100. Rapid Road usb, Amd scsi chip, Buster11. FTP service now with my Ethernet WD2TB Live Book, haha love it !
hp lappy.

http://www.youtube.com/user/lost666loven?feature=mhum
 

Offline DanAdamKOFTopic starter

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #7 on: March 17, 2012, 10:51:35 PM »
Quote from: lost_loven;684211
here is another link with a similar problem.. just reading it now.. might have some insight for you..
http://www.amiga.org/forums/showthread.php?t=20817
lost
Ooh, great link!  I didn't run across this before, thank you for pulling up something new.  I'm wondering how exactly piggy-backing works to test RAM, I guess I will need to pull up some more info, if this is something I want to do.  I may just do the below:

Quote from: spirantho;684207
Almost certainly a bad Chip RAM IC. It'll be  difficult to diagnose without removing each of the RAM chips I'm  afraid!
Missed this earlier.  I'm no stranger to soldering and  the board is the wonderful 80s spaced out through-hole non-rohs type, so  replacing the RAM outright seems simple enough, I'd probably just put  in some sockets and buy new RAM, could upgrade it to 1MB while I'm at  it.

Do you think this is a guaranteed fix?  I sort of dislike the shotgun approach to fixing things, but I guess it's worth a try.
 

Offline lost_loven

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #8 on: March 17, 2012, 11:02:45 PM »
My self, a500's are cheap and a dime a dozen, I have even had 2 just given too me.. I keep them for spares.. might be just as easy just to source out a another a500 and keep the chips off this one just for parts. As for a guaranteed fix i dunno.

lost
A3000D 2 meg chip, 4 meg fast,128 meg zorram! 16 gig scsi2sd, 3.1 ROM, A3640, Indivision ECS, X-surf-100. Rapid Road usb, Amd scsi chip, Buster11. FTP service now with my Ethernet WD2TB Live Book, haha love it !
hp lappy.

http://www.youtube.com/user/lost666loven?feature=mhum
 

Offline Castellen

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #9 on: March 17, 2012, 11:03:21 PM »
Quote from: DanAdamKOF;684216

Do you think this is a guaranteed fix?  I sort of dislike the shotgun approach to fixing things, but I guess it's worth a try.



The green screen means that the power on write then read test to memory has failed, which doesn't always mean that there is an issue with the memory ICs.  Can also be related to anything that shares the memory bus.  You can probably do some more tactical fault finding if you have an oscilloscope and the skills to use it.

Another quick thing to try is exchanging the two 8520 CIAs.  I've seen faults where one of them being bad, I forget which one, causes a green screen error.
 

Offline motrucker

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #10 on: March 17, 2012, 11:28:18 PM »
It also might be that: if there is no expansion card, that may have been installed as chip RAM (just a couple for pads to cut/solder) and now without the card, it's missing half of the chip RAM. If that's what happened, all you will need to do is pop in the RAM expansion card.
The green screen usually means chip RAM, not just RAM.
I hope this helps....
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Offline DanAdamKOFTopic starter

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #11 on: March 17, 2012, 11:35:49 PM »
Quote from: motrucker;684221
It also might be that: if there is no expansion card, that may have been installed as chip RAM (just a couple for pads to cut/solder) and now without the card, it's missing half of the chip RAM. If that's what happened, all you will need to do is pop in the RAM expansion card.
The green screen usually means chip RAM, not just RAM.
I hope this helps....
Is this something that comes like this from the factory?  I didn't notice anything like that, that would have been done by hand.  Could you elaborate on this some more?  I'm an Amiga newbie if that's not obvious:nervous:

The A500 came with a dodgy-looking trapdoor card (no identification on it at all, cheap-looking PCB) that I took out since it has a leaked battery on it.  I checked near there on the A500's board and it's unaffected.  The trapdoor board seems unaffected by the battery too, I should probably remove that though.  If getting pictures would help I can take some.

I'll exchange the CIAs a bit later, thank you Castellen.

As for getting a new Amiga, I guess I could, but I already spent sort of a lot to get this A500 and a C64 with a fair amount of accessories and hardware, and I prefer to fix things rather than replace them if possible.  I'm OK with spending a few bucks on old RAM, or more than a few bucks on two chip pullers (which I can reuse later so that's OK), but I'd like to hold back on buying a totally different Amiga if I can help it.
 

Offline motrucker

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #12 on: March 17, 2012, 11:40:34 PM »
I don't have an A500 here to jog my memory, but there are three solder pads just inboard (to the left, look from the front) that need to be joined/cut in a different configuration to use the 512Kb card as chip RAM.
I'll try to find a photo of a 6a mobo to show you which pads...
A2000 GVP 40MHz \'030, 21Mb RAM SD/FF, 2 floppies, internal CD-ROM drive, micromys v3 w/laser mouse
A1000 Microbotics Starboard II w/2Mb 1080, & external floppy (AIRdrive)
C-128 w/1571, 1750, & Final Cartridge III+
 

Offline motrucker

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #13 on: March 17, 2012, 11:44:52 PM »
No photos, BUT this covers what I am talking about. It lists the pads involved.

http://www.amibay.com/showthread.php?t=4722

See if this helps
A2000 GVP 40MHz \'030, 21Mb RAM SD/FF, 2 floppies, internal CD-ROM drive, micromys v3 w/laser mouse
A1000 Microbotics Starboard II w/2Mb 1080, & external floppy (AIRdrive)
C-128 w/1571, 1750, & Final Cartridge III+
 

Offline amiman99

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #14 on: March 17, 2012, 11:53:46 PM »
I made an 1MB chip RAM MOD on my  A500, if you can take pics of the jumper/pad areas we can identify if the mod was performed.
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