Looking for a couple tips re: Mac Plus analog board

[sambapati87]

Okay, I've read the famous PDF about classic mac procedures, and I'm pretty sure I need to fix the solder connections on the J1 connector. I'm a little unclear on exactly what to do, however.

I've circled what I believe to be the 4 solder "points" (not sure on the correct terminology here) that need fixing. There are blatant burn marks on the little foam pad that holds the cardboard protector to this part of the board, and I can see black around at least one of the joints. Should I try de-soldering these, then starting over, or can I just add a dab of solder to each one and be on my way? I guess most importantly, is the area I've highlighted in this image where I should even be looking?

FYI I'm not completely stupid when it comes to electronic pieces like this, I just want to make sure I know what I'm doing before I dive in with a soldering iron.

 

[Osgeld]

to do it right you should remove and re apply fresh solder (and flux)

if you just reflow you are adding alot of old oxidization and contamination to the joint, and it probably will not be any better than what you started with

if you add on top, you still have the problem above + you will most likely have way too much on it risking shorts and bridges

(there is some chemical sciences behind all of this if you feel like looking it up)

as far as the connector itself, i dunno ... i have not done this repair yet

 

[shred]

If you've never done any soldering before, I suggest you practice on an old junk board before taking to your Mac Plus board. It's very easy to apply too much heat for too long and end up cooking the copper tracks off the board.

One of the pins on that connector looks like it has been really hot. In this situation, it can be really hard to get the fresh solder to "take" to the pin. I suggest removing the connector from the board and cleaning that pin up with some fine emery paper, or if you have Dremel tool, the wire brush attachment on the Dremel tool. Make sure that the fresh solder flows evenly across the copper trace on the board and the pin and properly wets the joint. If you just blob the solder on, you'll be back to where you are now in no time.

 

[Mars478]

Get the smallest soldering iron you can. Put a dab of new solder to get a nice shiny look on the solder. Just DON'T DO WHAT I DID. Make sure you have a desoldering tool, in case you accidentally join to solder joints, if this happens DO NOT POWER IT UP. YOU WILL KILL THE ANALOG BOARD. Get a Desoldering tool and undo the mistake. I destroyed my Classic 2 this way.

 

[joshc]

A solder sucker/desoldering braid isn't really necessary. A bit of solder wick placed over the solder and then heated up does the same thing - and for a lot less money.

 

[sambapati87]

Thanks for the advice. What's the best way to get the analog board out without killing myself?

 

[joshc]

If you are not replacing components, then you don't really need to remove the analog board if you're just doing a bit of simple soldering. You have access to all the joints like it is now, with the vinyl sleeve removed.

 

[Osgeld]

A solder sucker/desoldering braid isn't really necessary. A bit of solder wick .

desoldering braid is solder wick

oh and for the record, one of those little red rubber radio shack suckers is like 5 bucks, or about the same as wick, I use the bulb to remove the bulk then the wick to clean up more, but thats not required

 

[sambapati87]

If you are not replacing components, then you don't really need to remove the analog board if you're just doing a bit of simple soldering. You have access to all the joints like it is now, with the vinyl sleeve removed.

That's what I figured, just thought it'd be a little easier to get at. I'm gonna give it a few days to let voltage dissipate then have a go at it.

 

[joshc]

desoldering braid is solder wick

Indeed it is, I'm getting my terminology wrong. I meant, a solder sucker/desoldering gun/desoldering station isn't necessary.

 

[tomlee59]

Get the smallest soldering iron you can. Put a dab of new solder to get a nice shiny look on the solder. Just DON'T DO WHAT I DID. Make sure you have a desoldering tool, in case you accidentally join to solder joints, if this happens DO NOT POWER IT UP. YOU WILL KILL THE ANALOG BOARD. Get a Desoldering tool and undo the mistake. I destroyed my Classic 2 this way.

I would offer quite different advice. To get this particular connector to solder properly requires a fairly robust iron. Small, low-wattage types will struggle to get the pins hot enough to solder well. A cold joint is a poor joint, so you can't skimp. Indeed, the high failure rate of this connector's joints is attributable to the high thermal mass, and the consequent inability of the original factory equipment to produce a good joint in the first place.

Also use solder fairly liberally (not so much for the solder as for the flux). The surfeit of flux will assure that oxidized residue will not get in the way of making a good joint. After removing the iron, verify that the joint stays smooth and shiny as it cools. Try not to disturb the joint mechanically as it cools, or you will vex the magical metallurgical gnomes that control the interface.

Then, to avoid the catastrophe that Mars478 alludes to, simply inspect your work carefully before re-applying power. One would think that this step hardly needs explicit mention, but data suggests otherwise.

 

[joshc]

Get the smallest soldering iron you can.

I would offer quite different advice. To get this particular connector to solder properly requires a fairly robust iron. Small, low-wattage types will struggle to get the pins hot enough to solder well.

I think Mars478 was actually referring to the size of the tip, not the iron itself (even though he said iron). Like tomlee59 said, a powerful soldering iron is best. I recommend a temperature controlled station, with a fume extractor, brass tip cleaner, and lead tin 63/37 solder with rosin core and 2% flux. Don't use lead-free solder, it is weaker and difficult to work with. In the long-term, you may find a temperature controlled station will eventually pay for itself as you do more soldering jobs.

 

[Mars478]

Yeah stupid me, I meant tip. Some of the joints are quite small. Tomlee: Yes data suggests otherwise. I may actually be selling the Classic 2! I got an offer from Classic Mac 500