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Author Topic: A500: Green Screen/11 blinks, reseating chips didn't help...  (Read 11648 times)

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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.
A500 KS 2.1, 1MB Chip, 68000
A600 KS 3.1, 2MB Chip, ACA630 32MB RAM
A1000 KS 1.3, 8MB RAM
A1200 KS 3.1, Blizzard IV 50MHz 64MB RAM
A2000 KS 2.1, 68030 25MHz, 6MB RAM
A3000 KS 3.1, 68030 25MHz, 16MB RAM
A4000 KS 3.0, 68040 25MHz, 16MB RAM
CDTV KS 3.1, 4MB RAM
CD32
(AROS BOX) Dead :(
 

Offline lost_loven

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #15 on: March 18, 2012, 12:10:28 AM »
did the battery damage the pcb? remove the battery and repair or jump what ever broken tracers on it.. better to have a 1meg machine then a 512k machine if reversing. Is there a 1 meg agnus in there?

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 !
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Offline lost_loven

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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 #17 on: March 18, 2012, 01:57:18 AM »
Swapped the CIA chips, no change.
I checked the jumpers and they are for sure unmodified.
The A500 board is not damaged from any leakage.
I had apparently overlooked branding on the trapdoor board, it's a "JEC 512k" (918000) http://amiga.resource.cx/exp/jec512 The battery on it has leaked but it doesn't appear to have done anything to the PCB.  With the trapdoor board installed and the switch closed, the screen goes black when the LED is doing its long pulse, and when the switch is open, there's only a tiny black line interrupting the green for a brief second (same behavior as when the board is disconnected entirely).

I dunno what more I can do right now.  If you guys could shine some light on this piggyback RAM test method (the link was broken in the thread this was linked from, here's a mirror: http://us4.aminet.net/aminet/docs/hard/Trouble.txt ), I could try that out.


Thank you all for your help so far!
 

Offline TheBilgeRat

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #18 on: March 18, 2012, 02:16:37 AM »
recapping it should be a no brainer.  PM Cosmos and he can whip together a bag of caps for cheap.  Just because they don't look fried doesn't mean they aren't.
 

Offline amiman99

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #19 on: March 18, 2012, 02:22:50 AM »
This is nice link for Amiga troubleshooting:
http://home.arcor.de/kickstart/TKA/Tutorials/troubleshooter/trouble1.html

According to the table possible problems are:  Agnus, Gary, DRAMS, U2 socket.

You may need at least a spare Agnus and Gary to troubleshoot the problem.
A500 KS 2.1, 1MB Chip, 68000
A600 KS 3.1, 2MB Chip, ACA630 32MB RAM
A1000 KS 1.3, 8MB RAM
A1200 KS 3.1, Blizzard IV 50MHz 64MB RAM
A2000 KS 2.1, 68030 25MHz, 6MB RAM
A3000 KS 3.1, 68030 25MHz, 16MB RAM
A4000 KS 3.0, 68040 25MHz, 16MB RAM
CDTV KS 3.1, 4MB RAM
CD32
(AROS BOX) Dead :(
 

Offline DanAdamKOFTopic starter

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #20 on: March 18, 2012, 03:54:26 AM »
Some more behavior to report: When you power on the A500, you can press  the caps lock button 12 times, and it won't respond to further presses.
 
 If you press Ctrl+A+A you can only toggle caps lock 8 times after a reset.

Quote from: TheBilgeRat;684241
recapping it should be a no brainer.  PM  Cosmos and he can whip together a bag of caps for cheap.  Just because  they don't look fried doesn't mean they aren't.
Is that a pretty  common cause of this issue?  I want to avoid the shotgun approach if I  can help it.  Then again, recapping is real cheap.

Quote from: amiman99;684244
This is nice link for Amiga troubleshooting:
http://home.arcor.de/kickstart/TKA/Tutorials/troubleshooter/trouble1.html

According to the table possible problems are:  Agnus, Gary, DRAMS, U2 socket.

You may need at least a spare Agnus and Gary to troubleshoot the problem.
I can at least say that the U2 socket looks sound.  None of the pins are bent, none have oxidation or corrosion, the Agnus is held tight, the pins on the bottom are connected perfectly, and the plastic on the socket looks fine (no cracking or any funny business).
 

Offline smerf

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #21 on: March 18, 2012, 04:00:07 AM »
Hi,

By golly that Amiga 500 knows it is St. Pats day, thats all

smerf
I have no idea what your talking about, so here is a doggy with a small pancake on his head.

MorphOS is a MAC done a little better
 

Offline Azryl

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #22 on: March 18, 2012, 04:53:44 AM »
You can boot the A500 without the keyboard attached. You will not be able to three-finger-reset of course.... but the caps-lock problem might be a bad CPU on the keyboard.

Az
Completely useless? I can always be used as a bad example  :lol:
 

Offline DanAdamKOFTopic starter

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #23 on: March 18, 2012, 04:55:38 AM »
Quote from: Azryl;684263
You can boot the A500 without the keyboard attached. You will not be able to three-finger-reset of course.... but the caps-lock problem might be a bad CPU on the keyboard.

Az
I've booted without the keyboard plenty of times.  I don't think the keyboard is defective per se, I saw in another "green screen" thread either here or on another Amiga board that someone noticed you could only toggle caps lock a few times.
 

Offline amiman99

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #24 on: March 18, 2012, 05:25:26 AM »
The number of times toggling the cap lock is related to the buffer in the keyboard. The keyboard buffer can only hold so many keystrokes before it needs to be emptied by the CPU.
So, that can only tell you that the buffer is not being emptied.
The CPU should be good because you are getting Error codes, if the CPU was bad then there will be no display and no error codes.
Maybe try to boot w/o floppy drive cable and see what happens, it may take little longer, just leave it on w/o floppy drive for a minute.


Quote from: DanAdamKOF;684255
Some more behavior to report: When you power on the A500, you can press  the caps lock button 12 times, and it won't respond to further presses.
 
 If you press Ctrl+A+A you can only toggle caps lock 8 times after a reset.

Is that a pretty  common cause of this issue?  I want to avoid the shotgun approach if I  can help it.  Then again, recapping is real cheap.


I can at least say that the U2 socket looks sound.  None of the pins are bent, none have oxidation or corrosion, the Agnus is held tight, the pins on the bottom are connected perfectly, and the plastic on the socket looks fine (no cracking or any funny business).
A500 KS 2.1, 1MB Chip, 68000
A600 KS 3.1, 2MB Chip, ACA630 32MB RAM
A1000 KS 1.3, 8MB RAM
A1200 KS 3.1, Blizzard IV 50MHz 64MB RAM
A2000 KS 2.1, 68030 25MHz, 6MB RAM
A3000 KS 3.1, 68030 25MHz, 16MB RAM
A4000 KS 3.0, 68040 25MHz, 16MB RAM
CDTV KS 3.1, 4MB RAM
CD32
(AROS BOX) Dead :(
 

Offline huronking

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #25 on: March 18, 2012, 07:24:56 AM »
Way back in the day we isolated bad ram by feeling for the one hotter than the rest. Worth a try.
 

Offline motrucker

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #26 on: March 18, 2012, 06:22:44 PM »
Quote from: DanAdamKOF;684255

Is that a pretty  common cause of this issue?  I want to avoid the shotgun approach if I  can help it.  Then again, recapping is real cheap.

No, bad caps rarely if ever cause this specific problem. It's some where in the chip RAM or custom chips or the pads I mentioned being re-configured.
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 #27 on: March 18, 2012, 06:34:37 PM »
I can't believe I can't find any pics on the internet!! Here is a video that shows you the exact pads I was talking about. Maybe you can tell if yours have been fiddled with.

http://www.youtube.com/watch?v=swt2-JiLYt8
 I sure hope something in the mess 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 lost_loven

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Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #28 on: March 18, 2012, 07:13:02 PM »
look at above post with pdf file. It has CLEAR pic's of the mobo and what to look for, just watched that video , its ok but pdf is more detailed with close ups.

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 spirantho

Re: A500: Green Screen/11 blinks, reseating chips didn't help...
« Reply #29 from previous page: March 18, 2012, 08:52:14 PM »
Piggy-backing chips often is worth a try - just stick the known good chip on top of the chip to be tested, such that all the pins are making contact correctly between the two. That way, if one chip has lost a connection internally, the good chip will set the output correctly as it'll be floating in the dead chip.

Testing for heat is not reliable. If it works, great, but the only time a dead chip will get hot is if there's a short circuit somewhere. If it's just a lost connection it'll be normal temperature.

The only surefire way to check for RAM being bad is to take the chip out and put it in a known good machine. One thing you can try though is to check the data line out of the RAM chip against ground - each of the chips should have roughly the same resistance between it and ground. If one is different, check that chip first.
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