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Old 04 October 2018, 18:39   #1
nolunchman
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trying to get my 3000T back in service

after 2 decades.

I want to revive my personal favorite computer of all time, but it looks like it will be a challenge. At the time I put it away and left the Amiga scene, I heard nothing of the battery issue. When dusted the tower off and tried to fire it up, all I got was a black screen with feint vertical stripes. I could reboot using my keyboard so that told me all is not lost (but pretty far gone).

I pulled the motherboard out and surveyed the damage. Took lots of pics so I won't go into detail, but my googleage and youtubeage of leaky amiga batteries has shown worse carnage. All is not lost.

In the 3kT, the battery is located right next to the math coprocessor and ROMs. 4 traces to the 68882 were severed. I attempted to repair the traces with 0.2mm wire. 5 wires took 3 hours. I felt like a neurosurgeon. All is not lost, but my patient is still in a coma.

I'm looking now to my fellow amiga devotees to point me in the right direction. Peruse the pics at your leisure. I'm hoping one of you sees or says something that leads to the revival of a very cool computer.

My gratitude in advance.

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Old 04 October 2018, 19:18   #2
Franchute13
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Hello ! You are welcome.
Cute mother! We are going to fix it.
Are you sure that the voltages of the PSU are correct?
Remember that in order for the A3000 D to work properly you must have the daughter board connected and a SCSI terminator connected. Surely for the A3000T it is the same.
First, take a picture of the problem area. That photo will be used to mark the tracks that are good and the ones that are wrong. Check the tracks that are good. Use the schematic of the A3000T to help you.
Another thing that may be wrong is the U195, try to change it.

This is my A3000D repaired
http://eab.abime.net/showthread.php?t=75257&page=2

Greetings.
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Old 04 October 2018, 20:18   #3
nolunchman
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thank you franchute. i will check the voltages. my 3000T does not have a daughterboard, only the pc slot. i saw your 3000 post the other day. good job and determination! i will tr to find a 3000T schematic. the motherboard is very different from the desktop version. i will buy another U195 chip. i have already ordered a set of capacitors. my 68882 looks pretty bad too, but if i disable it via jumper, does the computer still check for a good chip?
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Old 04 October 2018, 20:41   #4
nexus
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you missed a trace and i would fix the ones you did
you will need to move 2 anyways to get to the trace you missed
you should have cut back the length of exposed wire and straightened it

also your soldering job isnt good
i would get new wire and redo dont use that old
also if it too tiny for you get helpers
eg tape tweezers etc
tape can hold the wires in position and or tweezers
what i would do is flux the area and tin the iron
line up the wire to the trace hold it there with tweezers or a flat head screw driver whatever you have then solder
that way you dont need 3 hands
and you will produce better cleaner work

just fyi i have the same issue atm
though im doing a correct repair of the traces by replacing them and adding the mask back
though silkscreen be a tad harder but i have a few ideas

thing you also are forgetting is you need to clean that whole board not just that area
and there are many chips/vias etc the batt acid leaked into or under
trust me its a nightmare to repair
i got mine from japan this way earlier this year

Last edited by nexus; 04 October 2018 at 20:56.
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Old 04 October 2018, 21:29   #5
Hedeon
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Could always try to boot it with an A3630/A3640 first to check if anything else is damaged on the board except FPU/CPU. I have one in which the corrosion had spread 30cm to the CHIP RAM. There are some horror pictures of it on the net.

Did you clean the board? Otherwise the corrosion will continue.
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Old 05 October 2018, 00:30   #6
chue
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It is difficult to see, but there are some CPU pins that are possibly shorted.

Take a look at the 4th and 5th pins on the left side, counting from the lower left of the CPU image.
Also, take a look at the 6th and 7th pins on the bottom side, counting from the lower left.
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Old 05 October 2018, 00:53   #7
TjLaZer
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Same thing happened to mine and I was lucky to have a spare motherboard. I think the 3000T is very easily damaged by the leaky battery as you already know. Good luck.
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Old 05 October 2018, 01:45   #8
Franchute13
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Quote:
Originally Posted by nolunchman View Post
thank you franchute. i will check the voltages. my 3000T does not have a daughterboard, only the pc slot. i saw your 3000 post the other day. good job and determination! i will tr to find a 3000T schematic. the motherboard is very different from the desktop version. i will buy another U195 chip. i have already ordered a set of capacitors. my 68882 looks pretty bad too, but if i disable it via jumper, does the computer still check for a good chip?

schematic
https://www.amigawiki.org/dnl/schematics/A3000T.pdf


remember to stop the acid from the battery using white vinegar. Then wash the board very well.
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Old 05 October 2018, 02:48   #9
nexus
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vias are most important
and they act as drain holes and cant fuck the bottom good too
always make sure you get the corrosion out of them
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Old 05 October 2018, 04:26   #10
nolunchman
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Quote:
Originally Posted by Franchute13 View Post
schematic
https://www.amigawiki.org/dnl/schematics/A3000T.pdf


remember to stop the acid from the battery using white vinegar. Then wash the board very well.
exactly what i needed!
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Old 05 October 2018, 04:30   #11
nolunchman
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Quote:
Originally Posted by nexus View Post
you missed a trace and i would fix the ones you did
you will need to move 2 anyways to get to the trace you missed
you should have cut back the length of exposed wire and straightened it
yes it was difficult to work with such small traces. i wanted to lay down actual copper tracks but the traces are so close together. can you put up a pic of your board?
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Old 05 October 2018, 04:39   #12
nolunchman
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my PS voltages

1 0 (or not measureable)
2 -9.3
3 -5
4
5
6
7
9 5.02
10 5.17
11 5.17
12 5.17
13 5.2
14 10.6 (one time read 15v)
15 10.6 (one time read 15v)
16 5.03
17
18
19
20
21 5.17
22 5.17
23 5.17
24 5.17

pins 14,15 are supposed to be 12v but mine varied from 10-15v (no load)
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Old 05 October 2018, 05:14   #13
nexus
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i havent finished this project yet
still working on removing parts and getting all the corrosion
thats the hardest part
pain having to remove chips sockets etc
the fpu has to be takin off too etc
few chips pins are to far gone and need replaced etc
why i said it can be a nightmare and im in no hurry at this point
the board has been 99% neutralized
too many projects and life so its a slow fix

and i have about 10 A2000's with same issue that need to be done yet
did 1 already and replaced the batt with super caps
i have a huge list and little time
why i at least neutralized the whole boards
1st day i setup a station to soak boards in vinegar then wash then soak in alcohol
just fyi you need to get every little bit if not it will continue eating away at the copper
and getting it all out of the vias is a time intensive job

in the end ill cut and grind all that out then etch out a new then repair the mask etc
it will be like it never happened this is my personal so it will be done proper as im never selling it
and the bottom needs repair also due to like i said above about the vias acting like a drain hole for the acid
the surface tension of the acid lets it spread under the board

if i was doing this repair for someone it would cost them like the price of it lol
server damage these A3000T get from it
they have to be the worst amiga to have batt leaks

Last edited by nexus; 05 October 2018 at 06:10.
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Old 05 October 2018, 06:31   #14
nolunchman
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I think the fact that the 3kT motherboard is vertical lessened the damage. I stored mine standing up. When I opened it up after years of storage there was a dried puddle of bluish powder on the ethernet card. I thought nothing of it at the time. If the computer were horizontal, that puddle would have been right on the motherboard.

anyway, i pulled all the socketed chips and gave the mobo the vinegar and toothbrush treatment. one of my zip chips in the chip mem bank left 2 legs in the socket. add that to the grocery list.
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Old 05 October 2018, 07:10   #15
nexus
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yep thats 1 thing i have to do yet is take all them off and the sockets
you think its not bad till you really go looking
next thing you are like ffs damn it!
that batt is just in a bad spot on this amigas mobo

the japanese guy i bought this from planned on fixing then never got around too and stored it for years
then when he had a chance he was like damn too late too much damage so he decided to sell

Last edited by nexus; 05 October 2018 at 07:38.
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Old 05 October 2018, 23:22   #16
nolunchman
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Quote:
Originally Posted by nexus View Post
that batt is just in a bad spot on this amigas mobo
blame the engineers for not expecting their computers to go on for 25 years

after the board dried there was still some residue on the bottom. what is it? it's not from the battery. caps leaking?
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Old 06 October 2018, 00:00   #17
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I recommend you pull ALL socketed chips,inspect pins/sockets and reseat them as first thing.

Next check all jumpers are correct,one jumper wrong could cause no boot.People love to mess with them even though the machine may of worked at one time.

check the power supply under load. if voltages are ok go from there. You might change the "tick" jumper in case tick signal has failed to test it. you need to be close to +5,+12,-5,-12 etc

I have done many of that same repair over the years, i feel your pain.
I use 1 strand from stranded wire to fix traces like those. don't bother with insulated wire(i know you already fixed it,but just fyi).
I recommend you TIN all those traces first to protect and possible bridge any tiny breaks then tin the jumper wire,it will lay down very easily.flux is your friend!

do the trace repairs all have continuity?

I have found chip ram zips to fail sometimes in 3000T, Toshiba branded. not sure why but i had 5 machines over the years come through where i found bad chip ram.Maybe 5 failed in 20 years isn't much

It looks like something has hit the top of the Cpu, no telling what,i would inspect there are no shorted pins for sure. then go over the connections and look for popped solder joints.

the white residue on the above pic is likely leftover factory flux that wasn't washed off. unless the board was exposed to water or something at one time.

good luck.

Last edited by mech; 06 October 2018 at 00:12.
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Old 06 October 2018, 01:58   #18
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Quote:
Originally Posted by nolunchman View Post
blame the engineers for not expecting their computers to go on for 25 years

I would never expected to keep an old computer that long back then but I sure wish they would have chosen a different battery.

I have an Atari Mega STE and the battery was easy to replace and sealed in plastic leaving zero damage.

All three of my Amiga computers had some damage from bad batteries.
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Old 06 October 2018, 02:12   #19
nexus
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those batts leaked way before 25years
it was just bad design period to use those types
during this time you had batt packs in computers that were connected by cable just like fans
and the pack usually velcroed somewhere away from the board
and easily replaced when batt died
you can still buy those today using AA/AAA

today i just replace them with super caps
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Old 06 October 2018, 02:29   #20
mech
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Quote:
Originally Posted by nexus View Post
those batts leaked way before 25years
it was just bad design period to use those types
during this time you had batt packs in computers that were connected by cable just like fans
and the pack usually velcroed somewhere away from the board
and easily replaced when batt died
you can still buy those today using AA/AAA

today i just replace them with super caps

Exactly, by the 90's we saw some of them leak already, it was a well known thing to remove them by 1995.. i guess people ignored it.


Why do you use super caps? they are full of electrolyte and while they will last a long time they may leak eventually. the safe option is add a diode and lithium coin.
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