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CommodoreKid
June 24th, 2009, 11:23 AM
As replacement parts are currently en route for one of my C64s, Ive been trying to remove the underside metal plate from it.

The problem I have found is that these things are ridiculously hard to desolder. I have tried my useless solder sucker (lame), as well as desoldering braid (a copper woven strand that you put in between the iron and the solder to be removed) to no avail for either of them.

I have read that the solder on these joints happens to be very heat resistant, because this piece acts as a heat sink as well as RF shield. Therefor, my attempts haven't gone so well to free up only 10 solder joints (technically its 11, but one of mine was never attached by the factory).

So, Im sure that some of you have found an effective way to remove this large plate from the underside of your C64. I would love to hear how you were able to do it.

PS: I did read about somebody who just took pliers to it and ripped it right off- I would like to AVOID this strategy if at all possible.

RetroHacker_
June 24th, 2009, 11:35 AM
The solder braid isn't going to work too well in this situation - you already are having trouble heating the solder, you don't need to compound it by heating the braid as well.

You are correct about what is happening - the tin shield (as well as the ground plane on the board) is acting as a heat sink, and preventing you from heating it enough to melt the solder effectively. You need a bigger iron. I have a 40 watt iron I use for this bigger stuff.

You also don't need to remove all the solder on these tabs. Suck off what you can with the solder-sucker, but generally, you need to just heat it with the iron, and once the solder is melted and you can find the edge of the tab, lift it up with a tiny screwdriver or a pick.

-Ian

Bungo Pony
June 24th, 2009, 06:05 PM
For these types of things, I usually use a soldering gun instead of an iron. Guns are typically hotter and will do a good job at melting the solder.

Druid6900
June 24th, 2009, 08:12 PM
For these types of things, I usually use a soldering gun instead of an iron. Guns are typically hotter and will do a good job at melting the solder.

Agreed. You'd be there all day with a soldering iron. Just heat the joint up, bend it up a bit and move on to the next.

When you're going to put it back on, bend the tabs flat again, position it, heat it up with the soldering gun, add a little more solder and move on to the next.

5 minutes to get it off, 5 minutes to get it back on (make sure it's straight) and you aren't going to damage anything

CommodoreKid
June 29th, 2009, 06:55 PM
Success!

I bought a 40-watt soldering iron and some fresh flux (mine was actually for use with sweat-soldering pipe joints, this new stuff is for electronics).

It took a bit of finagling to get one or two of the tabs bent up, but all of them came off. I just removed some of the solder with the de-soldering braid, and bent the tabs up. That is, all but one. The last one right next to the power plug was just not melting, and I was getting antsy, so I just twisted and it popped off. It doesn't look pretty, but who cares?

So I successfully removed the RF shield/heat sink. Thank you for your advice on how to go about it.

Next comes de-soldering the existing RAM, when I get a chance. The replacement RAM arrived on Friday, but I'm waiting on the sockets to get here. I sent them by UPS ground, and they didn't arrive till today, and I left town yesterday, so they have to be forwarded my way. I figured sockets would be a good idea to prevent too much hassle next time I have a RAM problem.

Thanks again!

Druid6900
June 29th, 2009, 07:01 PM
Yeah, nothing like a little patience, eh?

Chuck(G)
June 30th, 2009, 07:25 AM
I bought a 40-watt soldering iron and some fresh flux (mine was actually for use with sweat-soldering pipe joints, this new stuff is for electronics).

I hope you didn't use that plumbing flux on any electronics--ever. It's typically acid flux (usually ammonium chloride-based) and will corrode the bejeezus out of electronic components with time. Same principle for flux for stained-glass work--it's murder on electronics.

When doing brasswork, I use an acid flux (Stay-Clean) and it'll corrode anything the vapors get close to.

Bungo Pony
July 2nd, 2009, 04:27 PM
May I ask what you're planning to do with your Commodore? Just replacing dead RAM, or improving/upgrading it?