A540 Help needed

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Trisomie21
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A540 Help needed

Post by Trisomie21 » Wed Jan 01, 2020 8:56 pm

On my A540 i had to remove the socket of IC58 due to damage from an leaking battery.

In this process, so it seems, some tracks of the Main pcb got damaged.

Can somebody help me with the correct routing of this Tracks to get it back into working Order?

Thanks a lot!
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IanS
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Re: A540 Help needed

Post by IanS » Wed Jan 01, 2020 9:04 pm

IC 58 is the IOC.

All details are in the TRM diagrams.

http://chrisacorns.computinghistory.org ... s.html#TRM
http://chrisacorns.computinghistory.org ... awings.zip (IOC is on page 3)

Is the chip still ok?

Trisomie21
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Re: A540 Help needed

Post by Trisomie21 » Thu Jan 02, 2020 8:19 pm

I got the A540 in a non working condition, so I dont know of the IOC is still working.

Is there a way to test it or just in this machine or in an other Archimedes?

Thank you for the links for the technical documents.

How to find the brocken tracks? Just doing an continuity test?

Thank you!

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IanS
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Re: A540 Help needed

Post by IanS » Thu Jan 02, 2020 8:46 pm

Trisomie21 wrote:
Thu Jan 02, 2020 8:19 pm
I got the A540 in a non working condition, so I dont know of the IOC is still working.

Is there a way to test it or just in this machine or in an other Archimedes?

Thank you for the links for the technical documents.

How to find the brocken tracks? Just doing an continuity test?
The IOC should work in any other Archimedes where the IOC is socketed, A3xx, A4xx (not A3000).

Continuity from each pin on the socket, to where it should go, following the circuit diagram, should get you there.

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gidandridge
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Re: A540 Help needed

Post by gidandridge » Thu Jan 02, 2020 8:48 pm

Yes if you have a multi-meter then just follow the tracks visual from start to end. Then test it at various points along the way with the continuity function on your meter.

This is, of course, easier said than done. Keep in mind that the if the track seems to stop at a 'hole' then it likely goes though to the reverse side of the board and continues from there. Also the tracks may disappear underneath other components and IC's which makes it tricky! :(

A mixture of the above and also using the schematics that Ian linked you too should get you there. Those will show you exactly where all the lines run to and from.

Once you have confirmed the breaks you can solder in some new wire's.

Good luck :D
Gav. :D

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Trisomie21
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Re: A540 Help needed

Post by Trisomie21 » Sun Jan 12, 2020 8:13 pm

I did a lot of testing now and I found two broken connections.

On Pin 17 IOC to IC 75 Pin 3

On Pin 42 IOC to IC 64 Pin 22

Next step will be replacing the socket and fixing wires on the broken tracks.
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Trisomie21
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Re: A540 Help needed

Post by Trisomie21 » Sun Jan 12, 2020 8:21 pm

This is the socket before it got removed.
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IanS
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Re: A540 Help needed

Post by IanS » Sun Jan 12, 2020 8:23 pm

Trisomie21 wrote:
Sun Jan 12, 2020 8:21 pm
This is the socket before it got removed.
Did the chip clean up ok? Do you have anything else you can test it in?

steve3000
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Re: A540 Help needed

Post by steve3000 » Sun Jan 12, 2020 10:45 pm

Definitely some damage to the PCB in the first photos, and looks like more than 2 tracks are broken?

For most of those tracks under the socket, you can clearly see where the track is damaged, so double check they are showing good continuity before fitting the socket. Once the socket goes back in the breaks will be harder to pinpoint. The A540 is very rare, and very fussy, so take your time.

Have you treated everything with vinegar to neutralise battery fluid? If you wanted to be really rigorous you could also consider cleaning up the area under the socket further with very light sanding (800 grit wet & dry, masking other areas off first), followed by cleaning with distilled water and IPA, then sealing with green pcb coating...

But I would suggest leaving the actual track wire repairs until after the socket is fitted - then you can run fine wire links between various IC legs on the underside of the board, which keeps repairs invisible once everything is refitted.

Trisomie21
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Re: A540 Help needed

Post by Trisomie21 » Thu Jan 16, 2020 4:22 pm

IanS wrote:
Sun Jan 12, 2020 8:23 pm
Trisomie21 wrote:
Sun Jan 12, 2020 8:21 pm
This is the socket before it got removed.
Did the chip clean up ok? Do you have anything else you can test it in?
Yes, I can test it in an working A310 that I have here!
steve3000 wrote:
Sun Jan 12, 2020 10:45 pm
Definitely some damage to the PCB in the first photos, and looks like more than 2 tracks are broken?
You are right, the two broken connections I mentioned in my post are the two that are to difficult to guess, so I repaired the all the other tracks and I test everything and now I´m left with this two.

So, I will see what and how to do, and I will take my time for this to get everything right and correct.

The board is an ISS. C version, and somebody did some handsoldering allready.

Trisomie21
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Re: A540 Help needed

Post by Trisomie21 » Mon Jan 27, 2020 11:39 am

On the weekend, I now had the time to fix the socket back and do the track repairs.

I have used fine wire to make the correct connections and put everything back together.

The A540 is back to live again! :D

The only problem that Im left with is, that the disk drive is not recognized and when I add a RAM Module the computer crashes/hangs up! :(
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Kazzie
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Re: A540 Help needed

Post by Kazzie » Mon Jan 27, 2020 12:17 pm

Well done =D>

Time to move on to other parts of the board now, I suppose... :roll:
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