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joethezombie
Twin Falls, ID

Posted Sat Aug 18, 2018 4:49 pm

I finally had time today to repair an Amiga 3000!


Battery leakage had caused the pins/solder in the through holes to turn into a weird substance that wouldn't melt with the iron. I had to drill out every battery compromised hole.
repair1.jpg

After drilling out all the holes, I used a fiberglass tipped pen to scrub all the corrosion off the copper layer. A lot had gotten under the solder mask, so I had to scrape it away. I also had to repair two traces near U480. When it was all clean and with no sign of corrosion left, I tinned it all with solder.
repair2.jpg

Finally, I covered the bare metal bits with new solder mask. I wish I would have went with a transparent version. The shiny tinned copper looked way better than the green slime. But hey, it's a good protective coating.
repair3.jpg

I placed new sockets for the Paula and Denise, and new sockets for the 74 series logic. Also replaced a smattering of capacitors and resistors that had been eaten away. For the ferrite bead at FB485, I used a 60 Ohm 50 MHz part. I was unable to find the exact specifications of the original Commodore part.

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joethezombie
Twin Falls, ID

Posted Sat Aug 18, 2018 4:51 pm

But does it work now? I plugged everything in, crossed my fingers, and flipped on the power:
reapir4.jpg
Woo hoo!

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Zippy Zapp
CA, USA

Posted Sat Aug 18, 2018 5:39 pm

Nice! Congrats on a great repair. Fortunately it didn't travel and destroy the Amber circuitry as often happens with A3000's.

Thanks for sharing.

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intric8
Seattle, WA, USA

Posted Sat Aug 18, 2018 8:17 pm

That is simply fantastic! Brought back from the grave. LOVE stories like this. Great work.

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mattsoft

Posted Sun Aug 19, 2018 8:54 am

That tinning of the mainboard looks nice!

I have a 3000 with similar damage. :( But she works! Except the scan doubler is wonky -- wavy lines. I'm thinking of replacing the 3 OKI RAM chips for the scan doubler, and the 3 inverter chips around the battery -- all have corrosion. Hopefully that will solve the problem.

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joethezombie
Twin Falls, ID

Posted Sun Aug 19, 2018 11:46 am

This one never worked, so I was so very happy when it sprang to life! A little jump, jig, and happy singing followed. Awesome that yours works, but yeah, that corrosion is not going to get any better. I say best to start saving that guy sooner rather than later!

Today I stole an SCSI2SD out of one of my Macs and put it in the Amiga. Works fantastic!

I still need to decide on the clock battery situation. I'm thinking of using a LIR2032 because they match the voltage and mAh of the original. I don't know if the Amiga can recharge it, though. Do I still need to use a diode?
reapir5.jpg

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Zippy Zapp
CA, USA

Posted Sun Aug 19, 2018 4:34 pm

The lithium rechargeable will not work. From what I have read there may be a risk of it popping. The voltage is too high to recharge those. The Amiga charge circuit is 5V and IIRC, those rechargeable lithium batteries require less and only .5mA. They also usually have specific charge cycles too, it is not a continuous charge type of battery like NiMh or NiCd.

Hope it helps...

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Dynamic_Computing

Posted Sun Aug 19, 2018 6:16 pm

You bring hope to me! I still have my A3000 from decades ago that quit working in about 1999 or so. I tried several times to bring it back but I have not touched it in about 15 years. Tine to dig it out and try again. Not sure why, as I have an A3000 tower that works fine. Just the challenge, I suppose.





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