Amiga 4000 restoration

Elerion

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As some of you know, I've been asking for various parts of Amiga 4000.

This thread will explain why, and document from what I started with to hopefully final result - Completely restored Amiga 4000.

Most of the parts i needed were provided by you, so on these photos they will be seen again.

So here we go.

Presenting two Amigas 4000 in absolutely terrible condition!

1.jpg

2.jpg

3.jpg

4.jpg


The reason why they look like they ware pulled out of the garbage is because they actually have been. :ninja:

One of these Amigas I already restored, and she's now on display in Peek and Poke Retro Museum. http://www.peekpoke.hr/en/ The restoration of the other one I will document here.
 
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Phipscube

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Wow this looks like a mighty task, good luck with it! it looks very exciting :)
 

Elerion

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Carwash yeah

Carwash yeah

Bathtime!

Case and all boards have taken a bath...
With a rough brush.

Battery had a bad leak so I soaked affected area in lemon acid for a few days.

I don't expect much, but at least it looks much better now. :D

5.jpg

6.jpg


PSU seems OK, so I'm powering her up for the first time! (
I've put a new battery hoping for the best.)

It's Booooting! Well after CTRL+A+A (It needs IDE FIX...)

But as one could expect damage was done.

- No fast ram
- RTC not working
:(
 
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rkauer

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Good luck fixing the FAST RAM slots! I had a ruined board where the battery spillage simply corroded away ALL SIMM traces!

The board gone to the bin after I salvaged the custom chips and sockets.:banghead:

But since your mobo are still working, all you need is an accelerator (don't count the A3640 as one) with its own memory.
 

Elerion

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Fast ram repair

Fast ram repair

After spending some time with a multimeter I found two broken traces. (y)
One was just under last sim socket, and the other one under U891.

Out it goes:

7.jpg

8.jpg


I used a special low melting point solder to desolder the chip using standard soldering iron.

Unfortunately trace was beyond repair, and I couldn't place a wire under the chip, or under the board, so I'll use a piece of wire on the visible side of the board. (It doesn't look nice, but it will work.) Repair under sim socked is close to invisible.

9.jpg


I also replaced some surrounding caps. (also were in bad condition)

10.jpg


Weird thing: Before the fix, I inserted A2000 8MB board just in order to boot the system and see if everything else is working. Amiga reported all 24 MB fast RAM, but system didn't boot because 16MB onboard ram was detected but faulty. I removed the 16MB from the board and tried again. Result was the same. 24 MB was reported even onboard ram was removed. Strange.
 
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Elerion

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Testing so far

Testing so far

A lot of parts I needed already arrived from various sources (80% Amibay sources :thanks:)

11.jpg


I'm assambling and powering up the Amiga.

12.jpg

14.jpg


Fast Ram is working! :p

Sysinfo result is as expected! Quite excited at this moment!:bounceBoingBall:
13.jpg


But I noticed more problems:

- RTC changes years, months and minutes, but date is locked at 6th and time is locked at 14. (Seems I'll be spending more time repairing the damage around leaked battery.)

- Audio sucks! One channel is almost completely silent, and there is a lot of white noise and a hum from PSU. (I think It's all due to dry caps, so caps on audio circuit and PSU will have to be replaced.

- PSU cooler is a bit loud
- Keyboard is a bit yellow. (Retr0bright will be employed. :D)
- Mouse needs new switches

But this ruined the excitement:

- 3640 card shows stability issues. (Even after replacing all caps on it.) After 10-20 minutes (when it heats up I guess) Amiga goes into reset loop.
This might be a tricky one. I'll try to resolder chips near caps leak, but It's a long shot and I'm open to suggestions. Hm... could it be due to noise form PSU? :huh:
68030 card works fine and stable.

BTW. When I got it, this A3640 was overclocked to 33.3MHZ. I Hope 68040 was not damaged by this. I have another 68040 but it seems completely dead, and can not test it. Oscilloscope would come in hendy right now, but I don't have one. Will try freeze spray to pinpoint source of instability.
 
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Elerion

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Good luck fixing the FAST RAM slots! I had a ruined board where the battery spillage simply corroded away ALL SIMM traces!

The board gone to the bin after I salvaged the custom chips and sockets.:banghead:

But since your mobo are still working, all you need is an accelerator (don't count the A3640 as one) with its own memory.

One trace under the last sim slot was damaged, but It was a piece of cake to remove the slot, fix the trace and resolder it. (Forgot to mention this.) The slots and the rest of the traces seem to be in good shape.

Yeees... Accelerator like PPC Cyberstorm would fit in just nice. :D
There were a few on the evilbay not a while ago, but since my wife will be ruining my finances over the holidays, I can not compete with her right now. :D
 

stachu100

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@Elerion,

Very nice job, congratulations!(y)
I will watch your thread very closely.
 

Elerion

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Caps replacement

Caps replacement

It's time to replace all caps.

Their condition is borderline. Not much spill, but still there is some.

Here is the picture of audio circuit before:
14a.JPG
:

and after:
17.jpg


Yes I noticed one cap was reversed. I've fixed it after taking the shots. :)

Replacing caps takes hours... a lot of patience... and a lot of flux as well:

15.JPG

16.JPG


Daughterboard got new ones too: :)

18.jpg


Replacing all the caps did not make a difference regarding problems with audio, RTC or A3640 on this Amiga, but it had to be done.

---------- Post added at 00:33 ---------- Previous post was at 00:09 ----------

In order to fix audio and processor problems, first thing I need is a good PSU.

PSU is not that bad. Well, maybe a bit too loud.

Before:

19.jpg


Afrer replacing all caps and a fan with silent 1000RPM one:

20.jpg


As for some before and after voltage measurements under full load, they are like this:

Voltage BEFORE:
5 - 4,99 VDC
12 - 11,92 VDC
-12 - -12,15 VDC

Voltage AFTER:
5 - 4,98 VDC
12 - 11,97 VDC
-12 - 12,15 VDC

Not much change you would say. True, but next measurement is important.

AC Component BEFORE: (lower is better)
5 - 0,087 VAC
12 - 0,209 VAC
-12 - 0,083 VAC

AC Component AFTER: (lower is better)
5 - 0,033 VAC
12 - 0,115 VAC
-12 - 0,032 VAC

This is quite good for computer PSU. And definite improvement over how it was before.

I've closed the Amiga and she is almost completely silent (CF instead of HD and great cooling fan)

---------- Post added at 00:53 ---------- Previous post was at 00:33 ----------

Another one smal fix today.

I got a very nice mouse, but buttons had to be pressed realy hard to produce a click.

Mouse has two screws under the commodore label.
To remove the label without breaking it i used my wife's hair fan:

22.jpg

23.jpg


Selling two used microswitches. 0€+Postage: :D

24.jpg


Replaced with new ones:

25.jpg


Afer reasambling, mouse looks and works like new.

26.jpg



On the next post, things will get more interesting.

Remained to be done:
- Audio circuit repair
- RTC circuit repair
- A3640 repair

Best regards,
Elerion

---------- Post added at 01:34 ---------- Previous post was at 00:53 ----------

I was just enyoing some demos on this Amiga, when completely unprovoked, one of the caps on EGS Spectrum just exploded, and burned with a flash and a lot of smoke.

27.jpg


I think cap is the only thing that got wasted. But I'll see tomorow. Now I'm off... :tired:
 
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rkauer

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Pretty common on the GVP 28/24, replace the capacitor (checking the polarity) and all will be fine.
 

salaxi54

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Awesome stuff! Takes a whole lot o' patience to treat them ladies well! (y)
 

Elerion

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Sound circuit repair

Sound circuit repair

Sound is working perfectly now.

I started by measuring signals on the operational amplifier LF347.
All signals were fine but one. Left audio out signal from Paula chip.

First suspect was a 47nF cap so I pulled it out (and it's right channel brother) and replaced them with fresh ones:

30.jpg


No result. Strange. This cap was only passive componet that if faulty could produce this kind of problem. Next suspect was Paula chip.

I was just about to pull her out, but before that i decided to check the trace between her and operational amp. Problem was here. Trace was broken. God damn via next to leeked cap again. I fixed it just by cleaning it, inserting a small piece of wire, and filling it up with solder.

Damage from leaked caps doesn't look as bad as damage from leaked battery, but creates the same (if not greater) problems.


---------- Post added at 23:12 ---------- Previous post was at 22:19 ----------

As you remember from earlier posts, my A3640 board is unstable. After few minutes of operation it chrashes the system and brigns Amiga to a reset loop.

There are two approaches to fixing this problem:

1) Long time spent with digiltal analyser or oscilloscope
2) Blind luck

Since i don't have tools to go with option 1, after careful consideration i decided to go with number two. :)

I'm using freezing spray to find component that's faulty. In theory if chip is producing problems when it gets warmed up, cooling it will return the board to stable operation.

So I waited until the board started to reset the Amiga and started freezing the chips one by one.

32.jpg


After a few minutes of trying, I found the chip that reacted to cold weather. It was seventh of nine 74FCT543 chips on this board. :roll: (Ok I am a Trekkie. How did you guess?)

I ordered a few replecement chips, but while I wait, let's pull out this one:

Desoldering in 5 simple steps:

1. Apply Flux:

33.jpg


2. Apply low melting point solder:

34.jpg


3. Pull the chip out

35.jpg


4. Remove the solder from the pads

36.jpg


5. Clean up with 2-propanol

37.jpg


And there. Place ready for a new chip:

38.jpg


I'm near the finish line now. (Just one hill to climb.) :D
 
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Elerion

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CD drive

CD drive

Amiga got one old but quite nice Plextor DVD RW.

39.jpg


Black detail on the drive door looks quite cool. :) Colour is not 100% match, but it's not that bad.

I'm still missing 3,5" front cover. :(
If you can help providing one, or have an idea on how to recreate one, please do.
 

ajk

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I came across a similar situation:

floppy_drive.jpg


This looked pretty silly, dunno what the previous owner was thinking, but I then solved it this way:

drive_bay_cover.jpg


This is simply a piece cut out of some spare bay cover panel. I first did a rough cut with a saw, then carved it into the right shape. You could mount such a piece in several ways, like a couple of drops of hot glue the inside or whatever; I used two little L-brackets bent out of sheet metal and double sided sticky tape to mount the piece on top of the floppy drive.

If you want to have the drive in the top position, you should of course cut some grooves in the plate to match the rest of the front panel... but that may be hard to do cleanly without suitable machines.

Hopefully that gives at least some ideas :)
 

gehtjanx

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I made a front CF (now changed setup in all 4000, now back CF ports) and didn't want to cut out original cover. I simply took the cover of an CD tray, it fitted perfectly in height, just cut the length and result was OK! Then I put a CF card hole. Now I got 2 drives and a back-CF port (where zorro slot covers are).

EDIT:
@ ajk:
First idea is horrible. Why not take a smaller second drive (or first drive ;) ). OK, you can built it back with a CD drive and 2 normal height disk Drives. Second idea similar as I said, but floppy should be on TOP as it was delivered. But seems color matching in your A4000 ;) mine are perfect white, so I didn't had that problem.

gehtjanx
 

ajk

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Well first idea is not mine, that's just how it was when I received the machine :)

The colour doesn't match so well, but that's beside the point, as you can obviously just find a similar shade panel to use. I hadn't yet retrobrighted the front bezel when I took those photos.

It's easy enough to make the grooves if you want to have the drive on the top, you just need to find a milling machine and a suitably sized bit (2.5mm was it? can't measure just now).
 

Elerion

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Well first idea is not mine, that's just how it was when I received the machine :)

Still it made me LOL. :LOL:

two ideas...

1.) Make a ceramics mold against front panel groves, and melt some plastic into it.

2.) Cut it from thermoplastic board.

...but color will not match.... unless I find donor Amiga and melt or cut original Amiga plastic...

Now why did I throw away that broken A600 case... :banghead:
 
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