The story of the mega A2000 job lot

omegamsx

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Hello ppl,

Here is the story of a project I've been working on for the last 5 months, currently nearing completion :)

In January of this year I was fortunate enough to acquire a lot of A2000 stuff from Amiga-Digital in NL.
This is what it looked like after arrival:

loot-1.jpgloot-2.jpgloot-3.jpgloot-4.jpgloot-5.jpg

10 cases, 12 motherboards, some zorro boards, some genlock & misc boards, MFM hdd's and a few power supplies.
After testing some worked, but most of them were having severe problems due to corrosion / varta death and or not working at all, black screen etc.

And it gets worse: lacking almost all screws! no case screws, motherboards held with only one screw.. Also not nearly enough working PSUs and keyboards.. a bunch of missing busters & other stuff. A serious project this is ;)

Now, after almost 5 months of debugging / repairing / soldering every weekend, I've managed to fully restore and clean every motherboard. Curious what 13 A2k mobos in a row looks like?

IMG_5925.jpg

From left to right: 2 donor boards (one rev4 one model a), 5 rev6.x boards, 4 incomplete rev4.x ones (buster missing), 2 complete rev4.xs.

The most broken of them all was this rev6.2 mofo:

2015-05-02 18.14.32.jpg

- All 8 drams dead
- 5 dead 74xx244/254 buffers
- A dead 74LS148
That took two weekends of logic probing and soldering, but it's 100% working ok now (y)
One never knows, but I'd think this one suffered a catastrophic PSU faillure... At least something overloaded the +5v rail...

Another nice one:

a2k-r4.1-1.jpga2k-r4.1-3.jpg

This babe required a new cpu and agnus socket (the latter was shattered to pieces)...

To be continued...
 

omegamsx

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Some before and after pics!

a2k-rev6.2-2.jpga2k-rev6.2-5.jpg
a rev 6.2


a2k-rev6.2-b-2.jpga2k-rev6.2-b-4.jpg
another poor 6.2

a2k-rev6.4-4.jpga2k-rev6.4-6.jpg
a2k-rev6.4-2.jpga2k-rev6.4-3.jpga2k-rev6.4-7.jpga2k-rev6.4-8.jpg
a very, very dirty 6.4, but now very very clean :)
If someone's curious to the cleaning process I use, let me know in the comments!
 

omegamsx

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Here's 4 of the Model A types I have:
IMG_5915.jpg
They are currently quite low on the priority list. All of them are working though.

Some drives, boards:
IMG_5910.jpgIMG_5912.jpgIMG_5913.jpg

Chassis, keyboards, recapped & refanned PSUs:
IMG_5927.jpgIMG_5928.jpgIMG_5929.jpgIMG_5933.jpg

Phew, well there you go..
Now on to the zorro boards..
 

omegamsx

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The boards include:

- A2090 x2 [works]
- A2090A x2 [works]
- A2091 [defective]
- GVP HC+8 series II [defective]
- Nexus ram+scsi [works]
- DKB RapidFire [defective]

The A2091 came without DMAC and SCSI controllers and no dram. After stealing the DMAC and WD from a donor A590 board, and replacing one of the 74F158s, installed v7 roms.. it came back to life!
Topped it off with 16 fresh OKI 514256 from the other 'bay so it's got 2MB now:
2015-05-02 21.23.21.jpg

The GVP took a little more effort, required a new 74AS244 and a 7407. Also other chips needed reflowing due to dull solder not making good contact anymore. But now all is right, board 100% restored (y)
gvp-hc+8-a.jpg
I'm missing the boot rom tho :(

The DKB board is beyond repair, as far as I can probe the Lattice chip is defective and that's unreplaceable unless I can find a donor board.

To be continued... :cool:
 

Jameson

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Finally, someone who has more working A2ks than I.... although all of mine are fully upgraded.... does that count? :)

How many Rev 6s are there? Now all you need to do is upgrade the Rev 6s to 2mb Chip ram on board (not too complex a hack and, except for the 8372B/8375B, very cheap to do), upgrade them to Super Denise and KS 3.1 and you will have some nice bases to build on.

The A2k is still my fave Amiga as they are so robust and expandable. Except for the Zorro 2 bandwidth limitations (which only shows its ugly head when you try and run 3D games in RTG at too high a resolution), you can have an A2000 which runs circles around a non-PPC A4000.

Have fun doing them up!
 

omegamsx

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Thank you, and yes that does count ;)

Minus my own and one A2k set that has been sold recently, there's still 4 rev 6s left. And I'm way ahead of you there, already stocked 5x KS3.1 and 4x super Denises :D The 2M chip mod is a no go since I can't source those agnusses... I have one 2M 'advanced chipmem adapter' which is working and has a 8372B though. Also I need to consider the amount of cash that I spend on spare parts... This is the list of parts I've aquired for the project so far:

18x zip dram
16x 514256 dram
1x Fusion 40 68040/25mhz/8M
4x 8373 denise
1x 8372A agnus
2x BUW13a
6x atx 2000
1x buster
1x a2630
6x LITBAT 5x KS31 ROM
1x a2091 roms
3x 74F158 and 5x SN7404D
1x rev4 mobo defect
1x a2000 rev6 complete
2x 74AS244
Atx psus & fans
2x rev6 1x chassis fdds psu kb
8x 514256 dram
8x 44256 dram
a2000 logos
DC6150 tapes
1x buster
Archive corp 2150S tapedrive
3x 1gb seagate hdd
1x syquest drive

:whistle:
 

Jameson

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....I recently purchased a couple of 8375B - 318069-03s these are the NTSC version (could not find PAL, but makes little difference) of the Agnus you need. Can PM you the sellers name in case he has more if you like...
 

Orcish75

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Amazing stuff Omegamsx!! :D Glad to see so many A2000's coming back to life. The A2000 is probably the most unloved Amiga in the community but the only way you'll get mine is to wrestle it from my dead body!
 

omegamsx

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@Jameson: hmm, the 318069-03 should be switchable using the pal/ntsc jumper right? If so, interested..

@Orcish75: I only stumbled upon A2000 a year ago when I repaired one for a friend.. Before that only A500 and A1200. Then I liked it and got one of my own, and then the lot.. couldn't resist.. And it's really rewarding if you can resurrect a dead board to live again :) I like it best when they are a challenge (y)


 

corpsicle

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Wow. Fantastic work. Keeping our beloved Amigas away from the trash-heap is hard work in normal cases, this is nothing short of a heroic undertaking.
There should be medals and a cermony to hand it out to people like you.
 

1200Danny

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You mention your cleaning method. I'd like to hear as have a couple of rotten 500+ boards to tackle.
 

omegamsx

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You mention your cleaning method. I'd like to hear as have a couple of rotten 500+ boards to tackle.

Ok! This method tries to salvage as much parts from the board as possible. If it's not necessary to replace the CPU socket avoid it. You'll damage traces almost certainly... The method is quite drastic though!


  1. Remove all socketed ICs from board (incl. agnus). Of course remove battery if still there..
  2. Use an anti corrosive agent (e.g. contact cleaner) and generously spray corroded area.
  3. Carefully remove big chunks of corrosion with something like flat head screwdriver. Also remove loose bits of pcb sealing (carefully!)
  4. In case of A2000 cpu socket: clean off corrosion from socket pins with something sharp like smd tweezers.
  5. Brush corroded area, clean with paper towel, spray again generously and repeat until paper towel stays clean.
  6. Wash the board in warm water plus de-greasing agent like dish soap. Use a big sink or bathtub. Brush generously the affected area and lightly the rest of the board, dont forget bottom side.
  7. Clean soap off of board spraying it with hot water.
  8. Shake off the water a bit, use canned air in case of A2000 slots to blow them out.
  9. Bake the board in the middle of an oven at 80 degrees celcius for 45 minutes. Put the board upside down. Don't put the board directly on metal but put something ceramic like coffee mugs in between. Do not pre heat the oven but start at room temperature.
  10. Do not take the board out of the oven yet: let it cool down gently for at least 15 minutes.
  11. Use a fibreglass pen to strip off any black pcb sealing without damaging traces. Visually inspect for broken traces.
  12. Inspect affected area. In case of A2000 cpu socket, pins need to be shiny again. If pins too far gone, broken off, not able to withstand gentle pressure then it will need replacement...
  13. Do continuity tests on affected area, in A2000 especially D0-D15 lines coming from CPU. Repair if needed.
  14. Seal exposed copper again with conformal coating.

In case of corroded 68000 cpu pins: spray with contact cleaner and rub very very gently with a very fine grit sanding paper (like 2000) until the pins are shiny again. In some A2000 boards a cheaper kind of socket was used with only contacts on the inside. In that case it can help a lot to gently bend the 68000 pins to the inside a bit for better contact.

Put all ICs back in their sockets, hook up the board and test. If its booting allright load something from a disk and do the wiggle test: gently flex the board to see if you can make it crash. On A2000 this mostly means the CPU pins aren't making good contact yet.

Good luck (y)
 

omegamsx

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A rev 6.4 board was missing its joystick port. The previous owner said he snapped it off.. :eek:
I dunno how that could have happened because it was snapped clean off indeed..

Before (after desoldering pin remains)/after:
a2k-joyport-1.jpga2k-joyport-2.jpg


Recently aquired a defective rev 4.3 board that had a broken in half video hybrid :shrug:
I mean, wtf are people doing to their Amigas? :picard

Before/after:
a2k-hybrid-1.jpga2k-hybrid-2.jpg


To be continued ;)
 
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