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Old 08 August 2017, 22:33   #1
Devil Master
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Amiga 3000 from Virtuality machine, green screen at boot

I'm attempting to fix an Amiga 3000 to make a Virtuality 1000SD machine functional again. So far, it boots to a green screen, and despite having read various guides, I'm stumped.

When I opened it for the first time, there was a corrosion stain under the battery, so I snipped off the battery and cleaned the whole motherboard with spray isopropyl alcohol.
I decided I would start booting it with no peripherals attached to pinpoint every arising problem, so I just connected the motherboard (with the daughterboard plugged in) to the power supply and the monitor, and switched it on. I expected to see the Kickstart screen, but I was greeted by a green screen instead. The guides identify it as a Chip RAM problem, so I performed various related tests.

I temporarily removed the socketed Chip RAM chips and tried to boot it again. Result = green screen.

I reinserted the chips, then I removed Agnus, Paula and Denise, cleaned their contacts, reinserted them and switched it on again. Result = green screen.

I tried to see what would happen if I booted it without the daughterboard on. I was expecting a yellow screen as per the guides I read, but there was the green screen again.

Then I read this page that distinguishes between GREEN and LIGHT GREEN boot screens, where "light green" indicates a CIA problem.

I haven't tried cleaning or swapping the CIAs yet. The boot screen looks like this: http://imgur.com/a/GOMqi
Is it green or light green?
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Old 08 August 2017, 23:47   #2
Cylon
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It does not only depend on the RAM chips but also on the address lines (PCB traces) to those chips.
Have a closer look at the mainboard itself, from top and beneath; and make sure you don't overlook battery damage. This stuff gets really close to DENISE and AGNUS and VRAM/clock and so on.
Make sure everything is ok. Oh, btw, there are VIAs under the chips as well.

Good luck and please do submit some hi-res pictures for all our eyes to have a look at.
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Old 09 August 2017, 00:17   #3
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I hope to be able to post some pictures by the end of the week.
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Old 09 August 2017, 05:54   #4
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Green screen = Chip RAM problem. The chip ram is the ram in DIP sockets near the RTC batter (in front of the machine); the 68000 is executing Kickstart but failing the memtest from $00000000+, and traces to chip RAM are probably damaged from the battery leak.
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Old 09 August 2017, 07:33   #5
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There's also some logic chips in the data and address bus of the chip ram which could be the cause here besides the ram chips and tracks. Basically everything between the CPU and the chip RAM chips should be checked so get the schematic out and start at one end.
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Old 09 August 2017, 13:04   #6
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Check closer for battery damage. Probe the PCB traces with a multimeter. You'll need to use the schematic to find all the RAM chip pins and trace back to the nearest probe point and eventually to something like the Agnus or 68030.

The barrel battery leaking and destroying the PCB area around the chipmem is common.
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Old 10 August 2017, 15:56   #7
Devil Master
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I haven't yet been able to take fresh pictures (the A3000 is not in my house, it's in an industrial building about 4 km away). However, when I had first opened it up (before cleaning it), I had taken some pictures for classification purposes. They are at http://imgur.com/a/CRRkA .
If you need to see an area I did not take a picture of, or you need fresh (post-cleaning) pictures, just tell me.
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Old 10 August 2017, 16:08   #8
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I see green pins all over the place despite the dirt. IMMEDIATE ACTION REQUIRED.
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Old 10 August 2017, 16:11   #9
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I shall keep an eye out! These systems were brilliant back in the day.
The board looks like it needs a full clean, refresh, re-cap, sockets done etc.

Thinking about it, are the games available/saved? With current tech would it be possible to emulate this stuff?

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Old 10 August 2017, 16:37   #10
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Quote:
Originally Posted by Cylon View Post
I see green pins all over the place despite the dirt. IMMEDIATE ACTION REQUIRED.
Can you point out the green pins on the picture? It's the first time in my life I've ever done this and I don't see them. Also, does it means that those lines are interrupted because they have been corroded all the way through?
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Old 10 August 2017, 16:56   #11
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here are some related posts:
Lemon Juice (killing battery acid)
Best solution to remove crystallic acid from battery leakage

look at the 1st image in this post, the connector. green vs copper colored.

the board got a lot dirt, maybe a dishwasher session will help too.
remove denise and paula chips, their pins are affected.
carefully with flat screwdriver, a bit on the left, next right, next left again,
until it lifts fully. dont scratch the pcb while doing so.
image attched is color/size reduced. for sure more areas.
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Old 10 August 2017, 18:12   #12
alexh
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Quote:
Originally Posted by emufan View Post
remove denise and paula chips, their pins are affected. carefully with flat screwdriver [snip] dont scratch the pcb while doing so
Or invest in an IC extractor (£5)
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Old 10 August 2017, 23:30   #13
Cylon
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Quote:
Originally Posted by emufan View Post
the board got a lot dirt, maybe a dishwasher session will help too.
remove denise and paula chips, their pins are affected.
carefully with flat screwdriver, a bit on the left, next right, next left again,
until it lifts fully. dont scratch the pcb while doing so.
image attched is color/size reduced. for sure more areas.
Right, almost all visible components in your picture have to come out, probably with sockets. All VIAs in this area are trashed as well, i think.
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Old 23 August 2017, 14:04   #14
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I have been helping (remotely) Devil Master with his VR machine, as I collect and restore them.
When we hit the green screen problem - I hit a a brick wall - as its only the VR system I know about.
I do know how the amiga controls the system via software, but I cant figure out Amiga issues, other than CIA problems.

DevMas, I hope yuo dont mind me jumping on this thread with my issues too, but the guys on here seem very helpful!

Right I also have Amiga 3000`s with problems, all from VR machines. Most have `died` from battery damaged.
Suggestions on any of the below would be helpful.

Ok - 3 (or 4) are just black screen when booting - with or without daughter card

1 is yellow screen with or without daugther card in (if I remember correctly.

1 was FINE - no battery damage, but one day just suddenly - just boots to black screen now.

1 flashes white and black screen - about 2 seconds black, 1 sec white.

Any ideas for my problems and further help on the green screen problem would be very appreciated!
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Old 28 August 2017, 12:53   #15
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there's only one way to fix dead A3000 properly. remove all parts in affected area, clean board, trace all tracks and join up with small wires. this takes about 1 year ;-)
I have 2 A3000 boards here. one still not working and one works when booted from cold but after warming up then resetting it stops booting. Obviously just more tracing is needed. I probably spent over 500 hours so far over the course of about 1 year. it's a terrible painful job :-(
Pity A3000 is not in amigapcb.org, otherwise it would be very easy to fix in a few days.
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Old 28 August 2017, 13:14   #16
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Hi.

1) You should wash with lemon in the area affected by the acid. If you do not do that, the acid will continue to damage.

2) You must remove the components of the area, clean, sanding, and control damaged tracks.

Here is my repair post.
Http://eab.abime.net/showthread.php?t=75257
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Old 28 August 2017, 13:22   #17
fordav1
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there are better ways to remove acid residue. using lemon is not a good idea because it will leave a sticky residue. however it's ok to use lemon if you also wash the entire area with water after then let it dry completely. I've seen posts where people dab lemon on a fully populated board using a cotton bud then wipe it off (not very well) which is really dumb because it leaves the board all sticky including having lemon juice under chips. In an extreme case like mine I simply put the whole board in the laundry sink with very hot water and citric acid granules (available at the supermarket in the cake making section.... also good for cleaning kettles ;-) and after 5 minutes removed, scrubbed it with a toothbrush and soap then rinsed with clean water and let it dry outside in the sun for a whole day.
The bottom line is repairing a non-working A3000 is going to require *A LOT* of PCB tracing and wire patching. Possibly hundreds of hours pouring over schematics and tracing with multi-meter. You may be lucky and find only 1 bad track/via but that's pretty unlikely. That is why many A3000's that died of battery damage have not been repaired.

Last edited by fordav1; 28 August 2017 at 13:33.
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Old 28 August 2017, 14:33   #18
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Quote:
Originally Posted by fordav1 View Post
there are better ways to remove acid residue. using lemon is not a good idea because it will leave a sticky residue. however it's ok to use lemon if you also wash the entire area with water after then let it dry completely.
It is true. It is very important after using lemon juice, clean the area well with hot water and then alcohol
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Old 08 January 2019, 23:51   #19
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I`ve just got one of mine working!
Had a green screen from boot...power light blinking.
So I googled.

Found it could be the agnus chip... so replaced - and now it `kinda` boots!

Kinda - as it will not find the hdd, just drops to kickstart screen. - a post going up for this though.
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