VOGONS


First post, by dataino.it

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I bet with a seller on ebay that I would fix his battery acid-ravaged motherboard. The premium an 80% discount on two other motherboards.

mat286-01.jpg
mat286-02.jpg

The steps I recommend from my experience to win are these:

1 ) Photographing every detail.
[+] Before any intervention, take a good picture of all the components involved
Folding them if necessary to read their values
Take photos from different angles
Take pictures of the entire motherboard

Here's what happens to a component when it is cleaned with vinegar or other products
The writing becomes illegible this applies to the integrated but especially to the ceramic capacitors, diodes and other components

mat286-03.jpg
mat286-04.jpg

2 ) Removal of components
[+] Eliminate as many components as possible
It is necessary to shed some light on the circuit board to be able to highlight all the damaged tracks.
Affected solder points should be scratched and stagnated before attempting
the suction of the pond.
Always use flux paste in the two phases.
Remove components in this way where the situation is simple but it does
procedure described above does not work, in the case of components
easy to find, proceed with the cutting of the feet leaving them as much
long as possible. The resistors and diodes only on one side, for the integrated cutting them all
Then they are eliminated with the help of tweezers and soldering iron.
At this point we proceed with the emptying of the pitches from the pond.

mat286-05.jpg
mat286-06.jpg

3 ) Cleaning the printed circuit.
[+] Vinegar, toothbrush and sandpaper 1000
The circuit must be completely cleaned up to highlight the copper of the tracks
and pitches.
You will do several passes with vinegar, and antioxidant and a toothbrush,
with subsequent washing with soap and water.
The most delicate phase is the one in which fine 1000 sandpaper must be used, without using
too much force and uniformly the tracks are cleaned from what remains of the protection.
When you start to see the copper, you stop and take a good picture of everything
soaked with isopropyl alcohol (makes the tracks more visible).

mat286-07.jpg

4 ) Reconstruction of the circuit
[+] Don't buy expensive wire to redo the tracks,
Remove the motor from a failed floppy and from some DVD player by recovering the motor wires
and you will have what you need in a convenient reel.
The advantage of using these wires is that they are protected with an insulating layer.
To be able to weld them you just need to place the soldering iron on the tip and wait a few seconds with tin.

mat286-08.jpg

The track to be rebuilt must be wet with flux, tinned delicately and then we lean on the wire that we have tinned to always weld it gently, you must not be in a hurry you can help yourself with tape to hold the wire still.
Fixed the wire on one side, proceed with attack glue and with the help of tweezers we will glue the wire on the damaged track, until we reach the other end of the track to join it or in the case of a joint on the pitch, prepare the tin wire and leave it in the hole.

5 ) Test Connections
[+] Everything will look okay but one is always missing.
Check with the tester all the tracks thus reconstructed

mat286-09.jpg

6 ) Component assembly
[+] All components possibly new
Solder in order:
Resistors, Diodes
Integrated circuit sockets (Better if tulip shaped)
Capacitors

In the case of 80286 I built a socket with streep lines this because if something went wrong I would only have to unsolder 7/11 pins against 68.

mat286-10.jpg

7 ) Test of connections
[+] Everything will look okay but one is always missing.
Check with the tester all the tracks thus reconstructed, concentrating above all on those that end in the integrated fields.

8 ) Power on and check
[+] Magical moment but surely ... Everything will seem ok but one is always missing.

If something does not come back to you, retrieve all the available information on the internet,
photos, manuals, position of the jumpers on UH19 you will already find a lot of files
motherboards with relative configurations (http://www.win3x.org/uh19/)

Debug with the help of an ISA card that reads the POST messages of the motherboard during boot.

Useful tool but remember that it does not say exactly what the problem is, in the case of the MAT286 being repaired the boot stopped with a value of "10" and 3 short beeps which translated would mean RAM problems, in reality it was the reconstructed track A15 of the processor that did not it was connected.

9 ) Let's play a game of Bubble Bubble
[+] Gratification needed after hard work

mat286-11.jpg

10 ) Take a nice photo
[+] Dump the bios

Upload of the beautiful photo and bios on http://www.win3x.org/uh19/ for future reference

mat286-12.jpg

To protect the circuit, treat the part of the exposed copper tracks with a transparent varnish and allow to dry for one or two days

Last edited by dataino.it on 2021-03-26, 08:44. Edited 1 time in total.

Reply 2 of 21, by Thermalwrong

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That's incredible work, and thanks for explaining the process. The trace routing is so tidy!
I get that that's a lot of work but really well done.

I've got some corroded 286/386 boards that I've not had much luck with, but I'll have to try doing something closer to what you've done. Usually if I see corrosion around the traces of a PQFP like that, I wouldn't touch it.

Reply 7 of 21, by zami555

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I'm very impressed with such a great job you did to resurrect this board back to life. And moreover I'm really happy to see you sharing your story here. This is really a huge inspiration for me to not give up with all fights to have my main boards back to live. Thank you very much for your post. You made my day!
Wish you all the best and more successes like this one in the future.

dataino.it wrote on 2021-03-25, 23:57:

[+] Everything will look okay but one is always missing.

That is really really true 😀 and again your geart spirit of not giving up!

Reply 11 of 21, by dataino.it

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Nexxen wrote on 2021-03-26, 01:57:

Dear friend, ottimo lavoro!
Got the 80% discount?

Yes for 30 Euro
2 motherboards

1 x ABC COMPUTER COMPANY, LTD. PRESTIGE 386
1 x Octet jaguar II + Original box

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Reply 13 of 21, by pentiumspeed

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Think that is difficult work? Do this with an cellphone repair running jumpers over broken traces using .05mm or .001mm jumper wires have to do that under microscope and tiny soldering irons, and watch maker tweezers.

This is my real current job doing cellphone repairs including the microsoldering. Before that my previous jobs was watch repair, then TV repair. And my hobby since childhood making electronics from kits and take apart from cast off and broken stuff and was my main toys including some typical toys.

😀

Cheers,

Great Northern aka Canada.

Reply 14 of 21, by Tetrium

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pentiumspeed wrote on 2021-03-27, 00:12:
Think that is difficult work? Do this with an cellphone repair running jumpers over broken traces using .05mm or .001mm jumpe […]
Show full quote

Think that is difficult work? Do this with an cellphone repair running jumpers over broken traces using .05mm or .001mm jumper wires have to do that under microscope and tiny soldering irons, and watch maker tweezers.

This is my real current job doing cellphone repairs including the microsoldering. Before that my previous jobs was watch repair, then TV repair. And my hobby since childhood making electronics from kits and take apart from cast off and broken stuff and was my main toys including some typical toys.

😀

Cheers,

Still, this is a very impressive repair job. It's probably the most impressive battery damage repair job I ever seen *thumbsup*.
Your skills from your job there sure show ^^

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Reply 16 of 21, by Tiido

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very awesome !

I tried to undertake such a thing once but ultimately failed because the vias were corroded through and the problem had gone in the inner layers...

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 18 of 21, by 386SX

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Impressive wires rebuilding near the chipset. But I'd not feel fine until I'd have used the right copper protection green pcb paint considering how close the wires are. 😉
I wish I had such soldering skills for many boards I couldn't save.

Reply 19 of 21, by douglar

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Tiido wrote on 2021-03-27, 11:45:

very awesome !

I tried to undertake such a thing once but ultimately failed because the vias were corroded through and the problem had gone in the inner layers...

That was a really impressive rebuild. Maybe the saving grace is that a 286 motherboard might have fewer layers?

What are those things by the ISA sockets? are those for SIPP memory?