The Resurrection or: The Three Damsels in Distress and other unconfirmed legends

hese

Well-known member
AmiBayer
Joined
Aug 24, 2008
Posts
1,679
Country
Finland
Region
Savo
Prologue

This is a story of three dead Amiga 1200 motherboards that were generously donated to me by Turran. Their journey has been recorded on Turran's journal:
How not to solder

Turran had a blast in experimenting with the boards, and so do I in restoring them. I just could not leave them in that condition.




Pictures of the boards in their initial condition.

Chapter 1: The Good

I started the restoration with the leftmost board which was in the best condition.

The first measurements indicated that some of the components were in short circuit. The customs chips were tested first and found to be fully functional, good news. The faulty components turned out to be one of the CHIP RAM ICs (resistance only 10 Ohms) and one decoupling ceramic capacitor (resistance 15 Ohms).



After replacing the short circuited components I tackled the Kickstart sockets. One of the socket had been removed and the other one was still partially hanging there. After removing the socket, one of the vias under the U6B caught my eye. The copper ring was corroded as if it had suffered from electrolytic capacitor leakage, but there were no elcos nearby. The via was broken. It was fixed with a tiny bit of jumper wire that was soldered to the both ends of the via.



The CHIP RAM ICs were an interesting case. Most of the legs were without solder, but there was concentration of a solder ball clinging on U18. Also eight pads were missing on U18. The pads were repaired with a thin copper wire. The wire could have been a bit longer on couple of the legs but get's the job done.



The diode near the keyboard connector had some jumper wires that were secured in place with glue. Removing the diode and cleaning it up revealed a couple of broken tracks. The tracks were fixed with a bit of copper and the diode was soldered back.



The video DAC chip needed also some attention. Most of the legs were missing solder and a couple of legs had a huge solder blob. Removing the chip revealed a few missing pads which were replaced with some copper wire.



The vias of every through-hole capacitors had taken some heat. In almost all cases one of the legs was wiggling in the hole and the other one held in place by a solder blob. After removing the capacitors it was clear that the missing vias had to be remade and the others probably reinforced. The missing vias were remade by soldering a wire to the top side and threading the other end through the hole. The end of the wire on the bottom side was then wrapped around the leg of the new capacitor and soldered in place. The fix turned out nice.



After soldering the capacitors and inspecting the board thorough once more, I plugged in the power cable and fired it up. And the Amiga greeted me with a nice Kickstart screen.

Total damage was:
15 missing pads, 9 broken traces, 4 broken vias, two burned components, a few missing parts (capacitors, ferrite beads, etc.) and some burned plastic.

Next I'll attempt to restore the board #2.

To be continued...
 

Turranius

New member
Joined
Mar 4, 2013
Posts
169
Country
Sweden
Region
Stockholm
Nice work! I just have to save face a bit here.. They arrived in this condition to me. I just documented the damage and left them as I figured I'd never get them running again anyway =) Not even I solder that bad. Heheh.

Can't wait to see what you can do with the other two ( I remember a lot of hot glue to hold on to chips in at least one of them ).
 

hese

Well-known member
AmiBayer
Joined
Aug 24, 2008
Posts
1,679
Country
Finland
Region
Savo
Sorry, I assumed you had a tongue in cheek "repair" with the boards after the custom chip was taken. Never questioned your soldering skills =)

Oh yes, the hot glue, it concealed a nasty surprise. Actually that motherboard was repaired quite a while ago.

But whether to continue this thread... Considering the amount of effort to document, photograph and write the story, I'm not certain if it's worth the effort if people do not show interest.
 

DutchinUSA

New member
AmiBayer
Joined
Feb 15, 2012
Posts
1,297
Country
Unites States
Region
Wisconsin
I always love seeing the pictures and the repairs you have done (y)

It always reminds me that I need to go through some of the stuff I have and check with you to see if you want to take a stab at repairing it. I just have to start setting some boards aside and document the problems first. A 4000D board with no video output comes to mind, it has some "repairs" done to it (not me). A 4000T board that was "repaired" by some guy in France, GVP A530 and probably more :)
 

hese

Well-known member
AmiBayer
Joined
Aug 24, 2008
Posts
1,679
Country
Finland
Region
Savo
Thanks for the reply, DutchinUSA. I may give this thread another go later, currently I've been working on a battery damaged A3000D board where the battery had leaked all over the VGA - CHIP RAM side. Every chip and socket on that side had to be removed (that's almost 60 chips :blink:).

I can give a shot on the faulty boards if you like. Motherboards can be restored nearly always, non-Commodore hardware not so often due to proprietary programmable chips.
 

hese

Well-known member
AmiBayer
Joined
Aug 24, 2008
Posts
1,679
Country
Finland
Region
Savo
Not related to the three boards above but I received an A1200 motherboard with same caliber of destruction. It was missing a PCMCIA connector for some reason. Someone used force to remove it and I had to use some Force to put it back.

Before


After


Not mint but turned out good enough.
 
Top Bottom