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Zippy Zapp
CA, USA

Posted Fri Sep 21, 2018 8:07 am

I don't envy anyone removing the SMD ICs on this board. I have not had much success recapping boards using hot air to remove them. I usually end up with torn pads, even with the correct nozzle. I know for this type of chip you can get a square nozzle that will fit directly over the chip so as to heat all sides at once.

You can also try ChipQuick. This seems to be a decent alternative:
See Video

Not sure if there is room, but perhaps, if you find spares, you could also cut each leg and desolder the feet?

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ClockworkCoder

Posted Sat Sep 22, 2018 11:40 am

Zippy Zapp wrote:I don't envy anyone removing the SMD ICs on this board. I have not had much success recapping boards using hot air to remove them. I usually end up with torn pads, even with the correct nozzle. I know for this type of chip you can get a square nozzle that will fit directly over the chip so as to heat all sides at once.

You can also try ChipQuick. This seems to be a decent alternative:
See Video

Not sure if there is room, but perhaps, if you find spares, you could also cut each leg and desolder the feet?
I'd actually seen that EEVBlog video ages ago, but had forgotten about it (didn't have a use for it at the time). Yes, that ChipQuik would be perfect for the job, but as you say, cutting off the legs, if that's possible, may be easier. I ended up cutting off the surface-mount capacitors after a couple of almost-failed attempts to remove them 'properly'.

Although, looking at the price of replacements, I think I'd need to try to find / preserve the good one if possible.

Anyway, I think I'm going to leave attempting that for a few months or so... been playing with my Amiga today (it's been working great :) ), and although the keys not working properly (and latterly the left mouse button), I can work around it. The c and v letters work more readily, and if I hold down n or m they do work eventually - just with repeated characters.

User avatar
ClockworkCoder

Posted Wed Oct 03, 2018 9:56 am

Not sure what's happened, as I haven't really done anything since the last time, but the "c" and "v" keys now appear to be working fine.

"m" and "n" are still as they were... so perhaps it's a dry solder joint, or something shorting somewhere... I'm thinking...

The other issue with the left mouse button is also odd. It works fine in games, and when I press it in workbench, it immediately works to pull the workbench window up or down, but doesn't work to interact with anything (ie. clicking on icons). Pressing the "Alt" key appears to issue a left mouse button click...

Could it be that one of the Amiga key (signals) is stuck on? I think the shortcut for the left mouse button should be Amiga + Left Alt, is this correct?

Incidentally I ordered a replacement power supply from a guy in Poland via Ebay, although they also have a website here: https://www.c64psu.com/

I haven't looked inside it yet, but the voltages were good, and it powered up the A1200 just fine :) Might take a look at its insides over the weekend now I've confirmed it's working.

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ClockworkCoder

Posted Sat Nov 16, 2019 4:19 pm

Bit of a late update, but I finally have my A1200 100% working, and loving it!

The YouTuber GadgetUK164 fixed it, and his video is here, for any that might be interested:

Thanks to everyone who made suggestions and tried to help me fix it along the way.

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JazzyTech

Posted Fri Feb 21, 2020 6:04 pm

ClockworkCoder wrote:
Sat Nov 16, 2019 4:19 pm
Bit of a late update, but I finally have my A1200 100% working, and loving it!

The YouTuber GadgetUK164 fixed it, and his video is here, for any that might be interested:

Thanks to everyone who made suggestions and tried to help me fix it along the way.
My first reaction to hearing about your problem was "check the CIAs" (as well as one IC on the keyboard IF it were an A500, which the first chip he reflowed I believe is the 1200's equivalent).
I own(ed) many Amigas, but stayed away from the 1200 due to the way it was built. With the ICs soldered directly to the board I knew that would make for some difficult repairs in the future. Back then some of us knew the potential and value of our machines and wanted them to live forever; much unlike today's mindset with most tech. Ah.. to be 20 again.. :)

I shot up quite a few of those CIAs back in the day due to homebrew builds and tinkering. I had four of them at the ready at any given time since my friends occasionally needed a set now and then: if your Amiga broke I was the guy you called to fix it. They were quite finicky depending on the motherboard revision (if I'm remembering correctly!) It's been over twenty years since I've worked on any Amigas, so I'm "rusty" to say the least...

Great seeing that video. Those fiberglass pens were hard to come by when I needed them back in the 80s. I had to order them from a company in the UK at the time.
I learned some things I didn't know about the A1200. Thanks for sharing this link! And great to hear the repair was wasn't an expensive one :) I hope it's still working?

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ClockworkCoder

Posted Sat Feb 22, 2020 4:09 am

JazzyTech wrote:
Fri Feb 21, 2020 6:04 pm
:) I hope it's still working?
It is working perfectly, thanks!

One gripe is that somehow my 8MB expansion isn't working, and only the 4MB is working, with or without the jumper. I suspect something may have gone wrong around the fly-lead and switch. In any case, I'll probably look for a replacement - at least it's not an intrinsic part of my precious :)





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