Help with gone wrong recapping attempt.

[Genjoke]

I come here to ask the favors of the recapping deities...

In my first attempt to make a recap of my ORIGINAL mac classic from back in the day, I destroyed some of the capacitors' pads while removing the old caps.

I suppose I can bodge wire the caps to the points shown below...

Two questions: am I right?? Where should I bodge the missing C2 pad to?

Thank you for any help!!


Edit: I finished recaping the board and it's working perfectly! Thanx again for the help.

 

[Kai Robinson]

You can download the Sprint layout file from the Macintosh Classic Reloaded GitHub and use the 'test' function in the demo version of Sprint, to find where the trace goes.

 

[Genjoke]

You can download the Sprint layout file from the Macintosh Classic Reloaded GitHub and use the 'test' function in the demo version of Sprint, to find where the trace goes.

Thanks! Now wish me luck soldering the new caps lol

 

[Cam]

I found this video helpful when I needed to replace some solder pads.

 

[YMK]

What was your decapping process?

 

[JDW]

I found this video helpful when I needed to replace some solder pads.

I must say, that is a great video. And yet, after all that work, he replaced the leaky electrolytic capacitors with new electrolytic, rather than choose a replacement with a solid electrolyte capacitor which will never leak. Oh well, at least they will likely get 20 years of use out of it before the replacements leak.

I myself used epoxy recently to repair a pad that had broken off on one of my SE/30 boards. I didn't use the high temperature kind shown in the video, but instead just used the 24-cure edition JB Weld, which worked fine to keep the pad in place even after the replacement cap was soldered onto it.

 

[Cam]

I must say, that is a great video. And yet, after all that work, he replaced the leaky electrolytic capacitors with new electrolytic, rather than choose a replacement with a solid electrolyte capacitor which will never leak. Oh well, at least they will likely get 20 years of use out of it before the replacements leak.

I myself used epoxy recently to repair a pad that had broken off on one of my SE/30 boards. I didn't use the high temperature kind shown in the video, but instead just used the 24-cure edition JB Weld, which worked fine to keep the pad in place even after the replacement cap was soldered onto it.

Right? Why would you recap with the cause of the problem!?! I've seen more than a few LB advertised as 'recapped' with pictures of electrolytics in place.

Good to know JB weld works just as well, as I have Color Classic II board on my bench that may need pad replacement - will know once I clean it up.

 

[Genjoke]

What was your decapping process?

Soldering iron + flux + bit of new solder. It worked fine with the first ones… I dunno if I got inpacient and pulled the later ones too much with the twezzers.

I heard hot air is better, but I dont have that equipment.

 

[3lectr1c]

Yeah, this is why I'd recommend twisting them off if you don't own a hot air station. Never lost a pad using it, it's safer than a soldering iron if you do it correctly. Good luck fixing it.

 

[JDW]

Yeah, this is why I'd recommend twisting them off if you don't own a hot air station. Never lost a pad using it, it's safer than a soldering iron if you do it correctly. Good luck fixing it.

I don’t mean to be critical whatsoever but I’ve always been curious about the twist off method. The reason why it always worried me is because you don’t always know the pad integrity. The pads need to have some level of adhesion to the PCB in order for the twist off method to even work. But if you’re twisting off a capacitor, couldn’t it be that fluid had leaked onto the pads below it, thereby partly or mostly detaching them from the substrate?

My concern is that if a pad is already partially detached, the action of twisting on the capacitor which is soldered onto the pad might tear off the pad completely. And I can’t help but feel that to be a legitimate concern even though most people who report success with a twist off method usually say that they have never harmed pad in the process.

 

[3lectr1c]

In cases of no to medium corrosion/leakage, the twist method works well. If you get a really bad board, you're probably going to need a hot air station anyway, as you will have serious cleaning to do underneath big surface mounted chips, requiring removal for proper repair. In those bad cases, yes, I would worry about using the twist method, but it's fine in my experience for most boards. My PowerBook 100 had some pretty nasty solder pads after I twisted the caps all off, very corroded and it took a while of adding fresh solder, flux, etc before they came clean. None broke though, and other than those pads, there wasn't any other corrosion to other components. So I'd take it on a case by case basis.

 

[Cam]

When it comes to removing caps from a board, I've settled on the dual soldering iron way. Heating both contact points and flipping the cap away has always left clean pads (as long as there's minimal corrosion) for me.

 

[YMK]

When it comes to removing caps from a board, I've settled on the dual soldering iron way. Heating both contact points and flipping the cap away has always left clean pads (as long as there's minimal corrosion) for me.

Agreed. I've been doing it this way for years.

I heard hot air is better, but I dont have that equipment.

Hot air has limited uses for recapping, typically when cap pads are right up against tall components, like on the Portable.

It works better with an IR preheating bed, otherwise a cold board will sink lots of heat.

Also with hot air, you risk melting nearby plastics and exploding caps.

Shielding parts with metal tape is tedious, so I'll always reach for the dual irons before the hot air.

A TS100 with BC2 tip is a great second iron.

 

[Cam]

It works better with an IR preheating bed, otherwise a cold board will sink lots of heat.

Also with hot air, you risk melting nearby plastics and exploding caps.

Preheating a board before using hot air is pretty much a must in my experience, or there's a real risk of the PCB warping - or maybe I'm just using to much heat.

 

[Genjoke]

When it comes to removing caps from a board, I've settled on the dual soldering iron way. Heating both contact points and flipping the cap away has always left clean pads (as long as there's minimal corrosion) for me.

I have another board to recap (a newly acquired Classic II), I'll try the two soldering irons approach!

 

[Elemenoh]

@Genjoke if your budget allows, a good pair of hot tweezers is IMO the best way to remove caps. No hot air to melt nearby nylon, easy to get into the toughest corners and no twisting.

Here's a vid of me removing all the caps from a Classic II MLB in just a few minutes with them the first day I used them. I've since gotten more comfortable with them and fly through cap removal without tearing pads and melting stuff.

Edit: video link

 

[3lectr1c]

Looks like you forgot to attach the video there. And yeah, soldering tweezers is probably the best way, though the one I looked at cost as much as my hot air station, so I haven’t got any.

 

[Elemenoh]

@3lectr1c Agree they can be expensive and it's not worth getting the cheap ($30ish) ones since they're such poor quality. I recommend finding a set that's high quality, but used, and ideally already compatible with your existing soldering station. I haven't used the Hakko tweezers, but I bet they're pretty good and they have a set that's compatible with the FX-888 which a lot of hobbyists already have. If you can find a used set of those for ~$100 that would be money well spent.

 

[Cam]

I have another board to recap (a newly acquired Classic II), I'll try the two soldering irons approach!

Got one of these LBs on my bench too; slooowly restoring it.

 

[Genjoke]

@Genjoke if your budget allows, a good pair of hot tweezers is IMO the best way to remove caps. No hot air to melt nearby nylon, easy to get into the toughest corners and no twisting.

Here's a vid of me removing all the caps from a Classic II MLB in just a few minutes with them the first day I used them. I've since gotten more comfortable with them and fly through cap removal without tearing pads and melting stuff.

Edit: video link

I saw those on a JDW's video. They seem great. The problem is that I don't know if it would be worth the investment, I don't see many motherbords to recap in the future.